Electrical & Electronics Engineering Vocabulary: 100 Key English Terms
Electrical and electronics engineers work with English every day: datasheets, schematics, standards, application notes, test reports and equipment manuals are almost always written in it. Knowing the core words for circuits, components, power systems, signals, microcontrollers, measurement, PCBs and electrical safety helps you read documentation quickly, work with suppliers and colleagues abroad and describe a design or a fault clearly.
100 terms
9 topics
58 core terms
200 example sentences
Read, understand, keep going
No account needed. Read the meaning, see where the term is used, then study the examples. Click any word in the lesson for help. You can also select a word and press Alt + Enter.
Voltage, Current and Power
voltage
noun
Meaning
The electrical pressure that pushes current through a circuit, in other words the potential difference between two points. It is measured in volts (V).
Where you use it
One of the first words in any electrical conversation. You measure, apply and supply a voltage, step it up or down, and talk about low, high, input, output and supply voltage. When giving a value, engineers simply say 'volts': 'it's sitting at 12 volts'.
Examples
The board needs a supply voltage of 5 V, but we're only measuring 4.6 V at the connector.
Check that the voltage is zero before you touch the terminals.
Usage note
Do not translate 'gerilim' as 'tension'. In English, tension is a mechanical pulling force; in electrical English it only survives in old phrases such as 'high-tension lines'.
Common phrases
supply voltage · input voltage · output voltage · high voltage · measure the voltage
The flow of electric charge through a conductor, such as a wire or a component. It is measured in amperes (A), which engineers usually just call amps.
Where you use it
Used constantly in design, testing and safety. Current flows, is drawn by a load and is limited, measured or sensed. Common phrases are current draw, rated current, leakage current, inrush current and overcurrent. In small electronics, values are usually in milliamps (mA).
Examples
The motor draws about 8 A of current at full load.
In sleep mode the current drops to 20 microamps, so the battery should last two years.
Usage note
As an adjective, current means 'güncel' (the current version). In electrical texts the noun almost always means akım.
Common phrases
current draw · rated current · leakage current · draw current · limit the current
How strongly a material or component opposes the flow of electric current. It is measured in ohms (Ω); for the same voltage, higher resistance means less current.
Where you use it
Used when checking wires, contacts, insulation and components. You measure resistance with a multimeter in ohms mode and talk about high or low resistance, contact resistance, insulation resistance and the resistance of a cable run.
Examples
If the trace is intact, the resistance between the two pins should be close to zero.
Corroded terminals increase the contact resistance and make the connection run hot.
Usage note
Turkish uses 'direnç' for both the property (resistance) and the component (resistor). In English they are different words: you measure the resistance of a resistor.
Common phrases
measure the resistance · contact resistance · insulation resistance · high resistance · low resistance
The rate at which electrical energy is used or delivered. In a DC circuit it equals voltage multiplied by current, and it is measured in watts (W) or kilowatts (kW).
Where you use it
Used for loads, supplies and components: power consumption, power rating, output power, power loss. In everyday speech power also means the electricity supply itself: 'the power is off', 'a power outage', 'power up the board'.
Examples
The heater uses 2 kW of power, so it should have its own 16 A circuit.
Make sure the power is off before you open the panel.
Usage note
Power (watts) and energy (watt-hours) are not the same thing. An electricity bill charges for energy in kilowatt-hours (kWh), not for power.
Common phrases
power consumption · power rating · output power · power loss · power outage
The basic rule that the current through a conductor equals the voltage across it divided by its resistance. It is usually written V = I × R.
Where you use it
Used in quick calculations every day: choosing a resistor, checking a current or estimating a voltage drop. Engineers say 'use Ohm's law' or 'by Ohm's law' and read the formula aloud as 'V equals I times R'.
Examples
By Ohm's law, 5 V across a 1 kΩ resistor gives you 5 mA.
Use Ohm's law to work out the value of the LED's series resistor.
Usage note
Write it with a capital O and an apostrophe: Ohm's law. The unit, ohm, is written in lowercase.
Common phrases
apply Ohm's law · by Ohm's law · use Ohm's law · Ohm's law calculation
Short for alternating current: current that changes direction many times per second. Mains electricity is AC, at 50 Hz in Turkey and Europe and 60 Hz in North America.
Where you use it
Pronounced as two letters, 'A-C'. Used on its own and before nouns: AC voltage, AC supply, AC motor, the AC side. Meters and labels show it as 'V~' or 'VAC'. In everyday English AC also means air conditioning, so context matters.
Examples
The unit runs on 230 V AC and has a built-in power supply.
Set the meter to AC volts before you measure the socket.
Common phrases
AC voltage · AC supply · AC motor · AC side · AC-DC converter
Short for direct current: current that flows in one direction only, usually at a steady value. Batteries, solar panels and most electronic circuits work with DC.
Where you use it
Pronounced 'D-C'. Used before nouns: DC voltage, DC supply, DC motor, DC bus, DC-DC converter. Labels show 'VDC' or a straight-line symbol. Engineers call a supply line 'the 12 V DC rail'.
Examples
The controller needs 24 V DC, so we added a DIN-rail power supply.
Measure the DC voltage across the capacitor with the power on.
Common phrases
DC voltage · DC supply · DC motor · DC bus · DC-DC converter
The total opposition a circuit offers to alternating current, combining resistance and reactance. It is measured in ohms and usually changes with frequency.
Where you use it
Used in AC circuits, audio, RF and signal integrity. Engineers talk about input and output impedance, the characteristic impedance of a cable or trace (often 50 Ω, or 90–100 Ω for differential pairs), impedance matching and high-impedance inputs.
Examples
The USB data lines need a controlled impedance of 90 Ω differential.
The ability of a component or structure to store electric charge, measured in farads (F). Practical values are usually in microfarads (µF), nanofarads (nF) or picofarads (pF).
Where you use it
Used for capacitors and also for unwanted effects, such as parasitic capacitance between traces, cable capacitance and the input capacitance of a probe or a MOSFET gate. Engineers add, measure or reduce capacitance.
Examples
The long cable adds too much capacitance, so the edges of the signal are rounded.
The total capacitance on the output should not exceed 470 µF.
The ratio of real power (in watts) to apparent power (in volt-amperes) in an AC circuit, between 0 and 1. A low power factor means more current is needed for the same useful power.
Where you use it
Used in industrial power and energy management. Motors and other inductive loads lower the power factor, so plants install capacitor banks for power factor correction (PFC). Engineers say the power factor is low, poor or close to unity.
Examples
Our power factor dropped to 0.82 after the new compressors were installed.
The capacitor bank keeps the power factor at around 0.98.
Common phrases
power factor correction · low power factor · unity power factor · improve the power factor
Short for root mean square: the effective value of an AC voltage or current, equal to the DC value that would deliver the same power. A mains voltage of 230 V is an RMS value.
Where you use it
Pronounced 'R-M-S'. Used when measuring AC: RMS voltage, RMS current, true RMS meter. For a pure sine wave the peak value is about 1.414 times the RMS value, so 230 V RMS has a peak of about 325 V.
Examples
Use a true RMS meter, because the current drawn by the drive is not a clean sine wave.
The output is 12 V RMS, which is about 17 V at the peak.
The reduction in voltage along a conductor or across a component as current flows through it. In long cables it means the load receives less voltage than the source supplies.
Where you use it
Used in cable sizing, power distribution and circuit analysis. Engineers calculate, measure and limit the voltage drop, often as a percentage. You also speak of the voltage drop across a resistor, a diode or a fuse.
Examples
On a 60-meter run the voltage drop is too high, so we need a thicker cable.
Measure the voltage drop across the shunt resistor to find the current.
Common phrases
calculate the voltage drop · voltage drop across · excessive voltage drop · cable voltage drop
The property of a coil or conductor that opposes changes in the current through it by storing energy in a magnetic field. It is measured in henries (H), often in µH or mH.
Where you use it
Used for inductors, transformers and motors, and also for unwanted effects such as the stray inductance of long wires and PCB loops. Engineers measure inductance with an LCR meter and talk about leakage inductance and parasitic inductance.
Examples
The long wires to the motor add inductance and cause voltage spikes when the MOSFET switches off.
Measure the inductance of the coil with the LCR meter at 100 kHz.
A closed path through which electric current can flow, made of a source, conductors and components. In building wiring it also means one branch protected by its own breaker.
Where you use it
Used in both electronics and installations. You design, build, test and simulate a circuit; in buildings you say 'the lighting circuit' or 'the kitchen circuit'. Common terms are circuit diagram, circuit board and control circuit.
Examples
I built the circuit on a breadboard first to check that the timing works.
Each socket circuit in the office has its own 16 A breaker.
Usage note
Pronounced 'SUR-kit'; the 'ui' is not pronounced as a separate sound.
Common phrases
build a circuit · circuit diagram · circuit board · control circuit · lighting circuit
An unwanted low-resistance connection between two points that should be kept apart, such as live and neutral. It causes a very large current that can damage equipment or start a fire.
Where you use it
Used in fault-finding and protection. Often shortened to 'short': 'there's a short on the board', 'a short to ground'. As a verb, two pins are 'shorted' or something 'shorts out'. Fuses and circuit breakers protect against short circuits.
Examples
A solder bridge between two pins caused a short circuit and the regulator burned out.
The breaker tripped immediately, so we suspect a short circuit in the cable.
Common phrases
short circuit current · short circuit protection · cause a short circuit · short to ground
A circuit with a break in its path, so no current can flow. It can be intentional, like an open switch, or a fault, like a broken wire or a cracked solder joint.
Where you use it
Used in testing and fault-finding. A multimeter shows an open circuit as 'OL' or infinite resistance, and technicians simply say 'it's open'. Open-circuit voltage is the voltage of a source with no load connected.
Examples
The heating element shows an open circuit, so it has to be replaced.
On a sunny day the panel's open circuit voltage is about 45 V.
Common phrases
open circuit voltage · open circuit fault · test for an open circuit · read open
A component that limits current or divides voltage by providing a fixed amount of resistance. Its value is given in ohms and its power rating in watts.
Where you use it
One of the most common parts on any board. Engineers choose a resistor by value, tolerance, power rating and package, and talk about pull-up resistors, current-limiting resistors and series resistors. Values are often written in short form: 4k7 means 4.7 kΩ.
Examples
Replace R12 with a 10 k resistor and check the output again.
This resistor gets hot because it dissipates almost half a watt.
Common phrases
current-limiting resistor · series resistor · resistor value · resistor color code · quarter-watt resistor
A component that stores electrical energy in an electric field between two plates. It is used to smooth supply voltages, filter noise, block DC and set timing.
Where you use it
Found in almost every circuit. Engineers talk about ceramic, electrolytic and film capacitors, decoupling or bypass capacitors next to ICs, and a capacitor's voltage rating. Often shortened to 'cap': 'add a 100 nF cap'.
Examples
Put a 100 nF capacitor as close as possible to the power pin of the chip.
The electrolytic capacitor was fitted backwards and bulged after a few seconds.
Usage note
Large capacitors can hold a dangerous charge after the power is switched off, which is why service manuals tell technicians to wait or discharge them first.
Common phrases
decoupling capacitor · electrolytic capacitor · ceramic capacitor · capacitor voltage rating · discharge a capacitor
A component, usually a coil of wire, that stores energy in a magnetic field and resists changes in current. It is used in filters, switching power supplies and chokes.
Where you use it
Used mostly in power electronics and RF design. Engineers choose an inductor by its inductance, saturation current and DC resistance. A 'choke' is an inductor used to block high-frequency noise, and 'coil' is the everyday word.
Examples
The inductor in the buck converter saturates above 3 A, so we need a bigger one.
We added a small inductor on the supply line to filter out the switching noise.
Common phrases
power inductor · saturation current · common-mode choke · inductor value
A semiconductor component that lets current flow easily in one direction and blocks it in the other. Its two terminals are called the anode and the cathode.
Where you use it
Used for rectification, reverse-polarity protection and protection against voltage spikes. Engineers talk about forward voltage (about 0.7 V for silicon), Zener and Schottky diodes and flyback diodes across relay coils. A diode is 'forward-biased' or 'reverse-biased'.
Examples
Add a diode across the relay coil to protect the transistor.
The diode is in backwards; remember that the stripe marks the cathode.
A semiconductor device used to switch or amplify signals. A small current or voltage at one terminal controls a much larger current through the other two.
Where you use it
Found in almost every circuit, from logic chips to motor drivers. Engineers distinguish bipolar transistors (BJT: base, collector, emitter) from field-effect transistors (FET or MOSFET: gate, drain, source). A transistor is turned on, turned off or driven into saturation.
Examples
The microcontroller pin can't drive the relay directly, so we use a transistor as a switch.
Check the base resistor; the transistor isn't turning on fully.
Common phrases
bipolar transistor · power transistor · transistor switch · turn on a transistor
Connected one after another along a single path, so the same current flows through each component. Resistances connected in series add up.
Where you use it
Used to describe connections: 'two resistors in series', 'connect the batteries in series'. The adjective is series (series resistor, series connection). Batteries in series give a higher voltage, and an ammeter is always connected in series with the load.
Examples
Put a 220 Ω resistor in series with the LED to limit the current.
Four 3.2 V cells in series give us a 12.8 V battery pack.
Usage note
For connections English says 'in series', not 'serial'. 'Serial' is used for data, as in serial port or serial communication.
Common phrases
connect in series · in series with · series resistor · series connection
Connected across the same two points, so each component has the same voltage and the current divides between them. The total resistance becomes lower.
Where you use it
Used for components, batteries, cables and generators: 'two capacitors in parallel', 'run the generators in parallel'. Batteries in parallel give more capacity at the same voltage. A voltmeter is always connected in parallel with what it measures.
Examples
Two 10 kΩ resistors in parallel give you 5 kΩ.
The two transformers run in parallel to share the load.
Common phrases
connect in parallel · in parallel with · parallel connection · run in parallel
A complete electronic circuit made on a single small piece of silicon and sealed in a package with pins. Microcontrollers, op-amps and voltage regulators are all integrated circuits.
Where you use it
Usually shortened to IC or simply called a chip. Engineers talk about the IC package (SOIC, QFN, BGA), pin 1, the part number and the datasheet. On schematics, ICs usually carry the reference designator U, as in U1 or U7.
Examples
The integrated circuit gets very hot, so check whether its output is shorted.
This integrated circuit is out of stock until next year, so we need an alternative.
Common phrases
integrated circuit package · driver IC · IC socket · pin 1
Short for light-emitting diode: a diode that gives off light when current flows through it in the forward direction. It needs a resistor or a driver to limit its current.
Where you use it
Usually pronounced as letters, 'L-E-D', though some people say 'led'. Used for indicators, displays and lighting: status LED, power LED, LED driver, LED strip. An LED turns on, blinks or flashes, or is dimmed.
Examples
The green LED blinks twice when the device connects to the network.
The LED is very dim, so check the value of the series resistor.
Common phrases
status LED · LED driver · LED strip · blinking LED · LED indicator
A device that opens or closes a circuit, either by hand or automatically. It can be mechanical, like a toggle switch or a push button, or electronic, like a transistor.
Where you use it
Used as a noun and a verb: switch on, switch off, switch over. Engineers talk about toggle switches, push buttons, limit switches and selector switches, and about contact types such as NO (normally open) and NC (normally closed).
Examples
The limit switch stops the door motor when the door is fully open.
Flip the switch to the off position before you change the fuse.
Common phrases
switch on · switch off · limit switch · toggle switch · normally open
An electrically operated switch: a small current through its coil moves contacts that switch a separate, often much larger circuit. Solid-state relays do the same job without moving parts.
Where you use it
Used in control panels, vehicles and electronics. A relay is energized or de-energized, its contacts open or close, and you can hear it click. Engineers talk about the coil voltage, the contact rating and NO/NC contacts.
Examples
You can hear the relay click, but the pump still doesn't start.
The relay coil is 24 V DC and the contacts are rated for 10 A at 250 V AC.
A circuit or IC that keeps its output voltage constant even when the input voltage or the load changes. It can be linear, such as an LDO, or switching, such as a buck converter.
Where you use it
Found on almost every board. Engineers choose a voltage regulator by input range, output voltage, current, efficiency and dropout voltage. Linear regulators are simple and quiet but turn the extra power into heat; switching regulators are more efficient but noisier.
Examples
The 3.3 V voltage regulator is getting very hot because it drops almost 9 V at 300 mA.
Replace the linear voltage regulator with a buck converter to improve efficiency.
Common phrases
linear voltage regulator · LDO regulator · switching regulator · dropout voltage · regulator output
Short for operational amplifier: an integrated amplifier with two inputs and very high gain. With a few resistors and capacitors around it, it can amplify, filter, compare or buffer signals.
Where you use it
Used in sensor interfaces, filters and analog front ends. Engineers talk about inverting and non-inverting amplifiers, the voltage follower (buffer), rail-to-rail op-amps, input offset voltage and the gain-bandwidth product.
Examples
We use an op-amp as a buffer between the sensor and the ADC.
This op-amp isn't rail-to-rail, so its output can't get down to 0 V.
A type of field-effect transistor controlled by the voltage on its gate. It is the most common switch in power electronics and digital chips, and its terminals are called gate, drain and source.
Where you use it
Pronounced 'MOSS-fet'. Engineers talk about N-channel and P-channel MOSFETs, the gate threshold voltage, the on-resistance (RDS(on)) and the gate driver. A logic-level MOSFET can be switched fully on directly from a microcontroller pin.
Examples
The MOSFET runs hot because the gate voltage is too low to switch it fully on.
Pick a logic-level MOSFET so that the 3.3 V output can drive it directly.
A metal part, usually finned aluminium, attached to a hot component such as a transistor or a regulator to carry heat away into the surrounding air.
Where you use it
Used in power electronics, drives and LED lighting. Engineers choose a heat sink by its thermal resistance (°C/W), mount the part with thermal paste or a thermal pad and sometimes add a fan. A part 'needs a heat sink' when it would otherwise overheat.
Examples
The MOSFET reaches 110 °C without a heat sink.
Put a thin layer of thermal paste between the regulator and the heat sink.
Usage note
Also written as one word, 'heatsink'. British English spells the metal aluminium, American English aluminum.
Common phrases
thermal resistance · thermal paste · mount on a heat sink · aluminium heat sink
The allowed difference between a component's real value and its nominal value, usually given as a percentage. A 1 kΩ resistor with 5% tolerance can measure anywhere from 950 Ω to 1050 Ω.
Where you use it
Used for resistors, capacitors, supplies and measurements. Engineers choose parts with tight or loose tolerance, check that values are within tolerance and run tolerance analysis on critical circuits. On through-hole resistors, a gold band means 5% and a brown band means 1%.
Examples
Use 1% tolerance resistors in the voltage divider, or the reading will be off.
A device that transfers AC power from one winding to another through a shared magnetic core, usually to step the voltage up or down. It does not work with DC.
Where you use it
Used from tiny signal transformers to huge power transformers in substations. Engineers talk about primary and secondary windings, the turns ratio, step-up and step-down transformers and the kVA rating. In Turkish the everyday word is 'trafo'.
Examples
The factory is fed by a 1600 kVA transformer that steps 34.5 kV down to 400 V.
Keep an eye on the transformer oil temperature during the summer peak.
Usage note
A transformer is not a 'transducer' (a device that converts one form of energy into another, such as a sensor) or an 'adapter' (a plug-in power supply).
Common phrases
step-down transformer · power transformer · primary winding · secondary winding · turns ratio
Any device or circuit that draws power from a source, such as a motor, a lamp or a heater. The word also means the amount of power or current being drawn.
Where you use it
Used in power systems, supplies and testing. Equipment runs at full load, at no load or under load; you connect, disconnect, shed or balance loads. Common terms are load current, peak load, resistive load, inductive load and load test.
Examples
The voltage is fine with no load, but it drops as soon as the load is connected.
We have to shed some load during peak hours.
Common phrases
full load · no load · under load · inductive load · load current
Describing an AC system with three voltages of the same frequency, each shifted by 120 degrees from the others. It is used to transmit power and run large motors efficiently.
Where you use it
Used before nouns: three-phase supply, three-phase motor, three-phase power. In Turkey and Europe a low-voltage three-phase supply is 400 V between phases and 230 V from phase to neutral. The opposite is single-phase, which most homes use.
Examples
The compressor needs a three-phase supply, so we can't plug it into a normal socket.
Check that the three-phase motor turns in the right direction before you couple it to the pump.
Usage note
Write it with a hyphen before a noun: a three-phase motor. Swapping any two phases reverses the direction of a three-phase motor.
Common phrases
three-phase supply · three-phase motor · three-phase power · three-phase system · single-phase
A machine that converts electrical energy into mechanical rotation. Most industrial machines use three-phase induction motors, while small devices often use DC or brushless motors.
Where you use it
Used in power, automation and product design. A motor starts, runs, stalls, overheats or trips. Engineers talk about rated power in kW, speed in rpm, starting current, the nameplate and the drives (VFDs) that control motor speed.
Examples
The motor nameplate says 7.5 kW, 400 V, 1450 rpm.
We installed a drive so that the fan motor can run at lower speeds at night.
Common phrases
induction motor · brushless DC motor · motor drive · starting current · motor nameplate
One or more electrochemical cells that store energy and supply it as DC. Capacity is given in ampere-hours (Ah) or milliampere-hours (mAh), and the voltage depends on the cell chemistry.
Where you use it
Used in portable devices, vehicles, UPS systems and energy storage. A battery is charged, discharged, drained or replaced. Engineers talk about lithium-ion and lead-acid batteries, battery life, state of charge (SoC) and the battery management system (BMS).
Examples
The battery lasts about eight hours with the screen on.
The UPS batteries are four years old and can no longer carry the load for ten minutes.
Usage note
Turkish separates 'pil' (small cells), 'akü' (lead-acid, as in cars and UPSs) and 'batarya' (packs, as in phones and electric vehicles). English uses battery for all of them; a single unit inside is a cell.
Common phrases
battery life · lithium-ion battery · charge the battery · battery pack · battery management system
A machine that converts mechanical energy, for example from an engine, a turbine or the wind, into electrical energy. A standby diesel generator supplies power when the grid fails.
Where you use it
Used in power plants, buildings and sites. A generator starts, runs, is synchronized with the grid or takes over the load during an outage. An engine and generator together are called a genset, and an automatic transfer switch (ATS) moves the load between the grid and the generator.
Examples
When the grid went down, the generator started and took the load in about ten seconds.
We test the standby generator under load once a month.
Usage note
In electronics, a 'signal generator' or 'function generator' is a test instrument that produces waveforms, not a machine that produces power.
Common phrases
standby generator · diesel generator · generator set · start the generator · synchronize a generator
A power electronic device that converts DC into AC. Inverters connect solar panels and batteries to the grid, supply AC loads in UPS systems and produce variable-frequency AC in motor drives.
Where you use it
Used in solar energy, UPS systems and industrial drives. Engineers talk about grid-tied and off-grid inverters, pure sine wave inverters, inverter efficiency and inverter faults. In industry, a variable frequency drive (VFD) is often just called an inverter.
Examples
The solar inverter shut down at noon because the grid voltage went too high.
The pump runs from an inverter, so we can change its speed from the control room.
Common phrases
solar inverter · grid-tied inverter · pure sine wave inverter · inverter fault · inverter efficiency
A circuit or device that converts AC into DC, usually with diodes. A bridge rectifier uses four diodes so that both halves of the AC waveform are used.
Where you use it
Used in power supplies, battery chargers, welding machines and drives. Engineers talk about half-wave and full-wave rectifiers, bridge rectifiers and the smoothing capacitor after the rectifier. In heavy industry, large rectifier units supply DC for processes such as electrolysis.
Examples
One diode in the bridge rectifier has failed, so the ripple on the output is much larger.
The rectifier turns the 230 V AC into about 325 V DC for the inverter stage.
One of the live conductors in an AC system, such as L1, L2 or L3 in a three-phase supply. It also means the timing position of a waveform, measured in degrees.
Where you use it
Used in installations and signal analysis. Electricians talk about phase-to-phase and phase-to-neutral voltage, a lost phase, phase rotation and balancing loads across the phases. In signals, two waveforms can be in phase, out of phase or have a phase shift.
Examples
The motor is humming but won't start; I think we've lost a phase.
There's a 30-degree phase shift between the voltage and the current.
Usage note
In everyday Turkish the live wire is simply called 'faz'. In English that wire is the 'live' (UK) or 'hot' (US) wire; 'phase' is used mainly in technical and three-phase contexts.
Common phrases
phase-to-phase voltage · phase-to-neutral · loss of phase · phase shift · phase rotation
The interconnected network of power plants, transmission lines, substations and distribution lines that delivers electricity to consumers. It is also called the power grid or the mains.
Where you use it
Used in energy, power engineering and renewables. Plants and solar farms are connected to the grid and feed power into it; homes draw power from it. Engineers talk about grid frequency, grid voltage, grid stability and grid connection; an off-grid system works without it.
Examples
The wind farm will be connected to the grid through a 154 kV substation.
When the grid fails, the UPS keeps the servers running until the generator starts.
Common phrases
power grid · grid connection · grid frequency · connect to the grid · off-grid
A facility in the power network where transformers step the voltage up or down, and where circuits are switched and protected with breakers, disconnectors and protection relays.
Where you use it
Used in transmission and distribution. Engineers design, commission, operate and maintain substations, and talk about the switchyard, busbars, feeders and protection relays. Small units that supply a neighbourhood are called distribution substations or kiosks.
Examples
The new factory will have its own 34.5 kV substation.
A fault at the substation left the whole district without power for two hours.
Common phrases
distribution substation · transformer substation · substation equipment · commission a substation
A high-voltage line, usually overhead on towers, that carries large amounts of power over long distances. In electronics, the term also means a cable or trace whose impedance has to be controlled.
Where you use it
Used in power engineering and in RF and high-speed design. Power engineers talk about overhead and underground transmission lines, line voltage (in Turkey mainly 154 kV and 380 kV), towers, conductors and line losses. RF engineers talk about matching a transmission line to its load.
Examples
The new 380 kV transmission line will carry power from the plant to the city.
At these frequencies the trace behaves like a transmission line, so its impedance must be controlled.
Common phrases
overhead transmission line · high-voltage transmission line · line losses · transmission tower
The number of times a signal repeats its cycle in one second, measured in hertz (Hz). Mains electricity in Turkey has a frequency of 50 Hz.
Where you use it
Used for mains power, clocks, radio and audio. You talk about high and low frequency, switching frequency, cutoff frequency and operating frequency, with values in kHz, MHz and GHz. In power systems, grid frequency has to stay very close to its nominal value.
Examples
The converter runs at a switching frequency of 500 kHz.
Equipment designed for 60 Hz may not run properly at our mains frequency of 50 Hz.
Common phrases
switching frequency · cutoff frequency · grid frequency · high frequency · frequency range
A voltage or current that carries information, such as a sensor reading, a sound or digital data. Signals can be analog, changing smoothly, or digital, switching between fixed levels.
Where you use it
Used across electronics and communications. Signals are sent, received, measured, amplified, filtered and sampled. Common phrases are input signal, control signal, signal level, signal integrity and signal-to-noise ratio (SNR).
Examples
The sensor signal is only a few millivolts, so we need to amplify it.
We lose the signal when the cable is longer than ten meters.
Common phrases
input signal · control signal · signal level · signal integrity · signal-to-noise ratio
A circuit or device that makes a signal larger, increasing its voltage, current or power while keeping its shape. How much larger it becomes is called the gain.
Where you use it
Used in audio, sensors, RF and instrumentation. Engineers talk about power amplifiers, audio amplifiers, instrumentation amplifiers and amplifier stages built with op-amps. An amplifier clips or saturates when its output reaches the supply limits.
Examples
The amplifier has a gain of 100, so a 10 mV input gives 1 V at the output.
The amplifier starts clipping when the input goes above 50 mV.
Common phrases
power amplifier · audio amplifier · instrumentation amplifier · amplifier stage · amplifier gain
Unwanted random or interfering signals that mix with the signal you want and make it harder to measure or use. It can come from components, power supplies, motors or radio sources.
Where you use it
Used in analog design, measurement and EMC. Engineers reduce or filter noise and talk about switching noise, electrical noise, the noise floor and the signal-to-noise ratio. Cables and traces can 'pick up' noise from nearby sources.
Examples
There's a lot of noise on the ADC readings when the motor is running.
Route the sensor cable away from the drive so it doesn't pick up noise.
Common phrases
switching noise · noise floor · pick up noise · reduce noise · signal-to-noise ratio
The ratio of a circuit's output to its input, showing how much it amplifies a signal. It can be given as a plain number, such as ×10, or in decibels.
Where you use it
Used for amplifiers, antennas, control loops and sensors. Engineers set, adjust, increase or reduce the gain, and talk about voltage gain, open-loop gain, unity gain and gain in dB. Too much gain can make a circuit unstable or cause clipping.
Examples
Reduce the gain to 20, otherwise the signal saturates the ADC.
The new antenna has a gain of 5 dBi.
Common phrases
voltage gain · unity gain · open-loop gain · adjust the gain · gain stage
The range of frequencies a circuit, instrument or channel can handle well, usually up to the point where the signal falls by 3 dB. In communications it also means data capacity.
Where you use it
Used for amplifiers, filters, oscilloscopes and communication links. Engineers say an oscilloscope has 100 MHz of bandwidth, an amplifier's bandwidth is too low, or a signal needs more bandwidth. In networking, bandwidth is given in Mbps or Gbps.
Examples
A 20 MHz scope doesn't have enough bandwidth to show these fast edges.
Limit the bandwidth of the amplifier to 10 kHz to cut the noise.
Common phrases
signal bandwidth · 3 dB bandwidth · limit the bandwidth · oscilloscope bandwidth
A circuit that lets some frequencies pass and blocks or weakens others. Common types are low-pass, high-pass, band-pass and notch filters.
Where you use it
Used in power supplies, audio, sensors, RF and EMC. Engineers design, add or tune a filter and talk about the cutoff frequency, the filter order and RC, LC or active filters. As a verb: 'filter out the noise'. A digital filter does the same job in software on sampled data.
Examples
Add a simple RC low-pass filter in front of the ADC input.
The EMI filter on the mains input keeps switching noise from getting back into the grid.
Common phrases
low-pass filter · high-pass filter · cutoff frequency · EMI filter · filter out
The shape of a signal when its voltage or current is drawn against time, such as a sine, square, triangle or sawtooth wave.
Where you use it
Used whenever signals are measured or generated. Engineers capture, inspect, save and compare waveforms on an oscilloscope, and describe them as clean, noisy, distorted or clipped. A 'scope shot' is a saved picture of a waveform for a report.
Examples
The output waveform should be a clean square wave, but there's ringing on the edges.
Save the waveform and attach it to the test report.
Common phrases
square waveform · sine waveform · capture a waveform · distorted waveform · output waveform
A logarithmic unit (dB) that compares two power or voltage levels. An increase of 3 dB roughly doubles the power, and 20 dB means ten times the voltage.
Where you use it
Written dB and often read 'dee-bee' in the lab. Used for gain, loss, noise, filters, antennas and sound levels. Engineers say a filter is '3 dB down' at its cutoff or a cable has '2 dB of loss'. Variants such as dBm, dBV and dBi use fixed reference levels.
Examples
The new filter gives us about 40 decibels of attenuation at 1 MHz.
The signal dropped by six decibels, which means the voltage has halved.
Common phrases
3 dB point · gain in decibels · dB loss · decibel scale
How many times per second a signal is measured when it is converted to digital form, given in samples per second (S/s) or hertz. It must be more than twice the highest frequency in the signal.
Where you use it
Used for ADCs, oscilloscopes, audio and data acquisition. Engineers set, raise or lower the sampling rate and refer to the Nyquist rule: if the sampling rate is too low, aliasing distorts the result. Oscilloscope specifications call it 'sample rate', in MS/s or GS/s.
Examples
We need a sampling rate of at least 10 kHz to capture the 2 kHz vibration properly.
Audio CDs use a sampling rate of 44.1 kHz.
Common phrases
high sampling rate · sample rate · Nyquist frequency · increase the sampling rate
A small computer on a single chip, with a processor, memory and input/output peripherals. It runs firmware to control devices such as appliances, sensors and motors.
Where you use it
Used in embedded systems and product design. You choose a microcontroller by core, memory, peripherals and price, then program or 'flash' it. Often shortened to MCU or 'micro'. Well-known families include STM32, PIC, AVR and ESP32.
Examples
The microcontroller reads the temperature sensor every second and switches the fan on when needed.
We moved to a microcontroller with more flash because the firmware no longer fits.
Usage note
A microcontroller (MCU) has its memory and peripherals built in; a microprocessor (MPU) usually needs external memory and runs a full operating system.
Common phrases
program a microcontroller · 8-bit microcontroller · low-power microcontroller · microcontroller board
Short for general-purpose input/output: a microcontroller pin that firmware can set as an input to read a logic level or as an output to drive something.
Where you use it
Pronounced 'G-P-I-O'. Engineers configure a GPIO as an input or an output, set it high or low, read it, enable its internal pull-up and attach an interrupt to it. Each GPIO has a limit on the current it can source or sink.
Examples
Configure GPIO 5 as an output and use it to switch the relay driver.
We ran out of GPIOs, so we added an I/O expander on the I2C bus.
Common phrases
GPIO pin · configure a GPIO · set the GPIO high · GPIO interrupt
Short for analog-to-digital converter: a circuit that measures an analog voltage and turns it into a number a processor can use. Its resolution is given in bits, for example 12-bit.
Where you use it
Pronounced 'A-D-C'. Built into most microcontrollers and also sold as separate chips. Engineers talk about ADC resolution, sampling rate, reference voltage, ADC channels and raw ADC counts. A 12-bit ADC gives values from 0 to 4095.
Examples
The ADC reads 2048 at mid-scale, which is about 1.65 V with a 3.3 V reference.
We need a 16-bit ADC to measure such small changes from the load cell.
Short for pulse-width modulation: switching a signal on and off quickly and changing how long it stays on in each cycle (the duty cycle) to control the average power.
Where you use it
Pronounced 'P-W-M'. Used for LED dimming, motor speed control and power converters. Engineers set the PWM frequency and duty cycle, generate PWM with a hardware timer and talk about a PWM output or a PWM signal.
Examples
At a 50% duty cycle, the PWM signal gives the motor about half of its full voltage on average.
Raise the PWM frequency above 20 kHz so that the motor doesn't whine.
Common phrases
PWM signal · PWM frequency · duty cycle · PWM output · PWM dimming
Software stored in a device's non-volatile memory that controls its hardware directly, such as the program running on a microcontroller.
Where you use it
Used in embedded systems and product support. Engineers write, build, flash and update firmware, and talk about firmware versions, firmware bugs and over-the-air (OTA) updates. 'Flash the firmware' means loading it into the device's flash memory.
Examples
Which firmware version is on the units that failed in the field?
After the firmware update, the sensor readings are stable again.
Common phrases
firmware update · firmware version · flash the firmware · embedded firmware · OTA update
A regular square wave that sets the timing of a digital circuit so that all its parts act in step. Its frequency, for example 16 MHz, sets how fast a processor runs.
Where you use it
Usually just called the clock. It comes from a crystal, an oscillator or a PLL, and engineers talk about clock frequency, clock source, clock speed and the clock line of a bus such as SPI or I2C. Data is often read on the rising or falling edge of the clock.
Examples
The clock signal on the SPI bus is 8 MHz, so keep the traces short.
Without the external crystal there's no clock signal, so the chip falls back to its internal oscillator.
Common phrases
clock frequency · clock source · rising edge · external clock · clock line
A resistor that connects a signal line to the supply voltage so that the line stays at a defined high level when nothing is driving it, instead of floating.
Where you use it
Used on buttons, reset lines, open-drain outputs and buses such as I2C. Typical values are 4.7 kΩ to 10 kΩ. Many microcontrollers have internal pull-ups that firmware can enable. The opposite is a pull-down resistor, which holds a line low.
Examples
The button input is floating because there's no pull-up resistor on it.
Add 4.7 k pull-up resistors on SDA and SCL.
Common phrases
internal pull-up · pull-up resistor value · pull-down resistor · enable the pull-up
Short for universal asynchronous receiver-transmitter: a hardware block that sends and receives serial data over two lines, TX and RX, without a shared clock.
Where you use it
Pronounced 'YOU-art'. Used for debug consoles, GPS and modem modules and links between boards. Both sides must use the same baud rate, such as 9600 or 115200. TX on one device goes to RX on the other; RS-232 or RS-485 transceivers extend the distance.
Examples
Connect a USB-to-UART adapter to see the debug messages at 115200 baud.
Nothing comes out of the UART because TX was wired to TX instead of RX.
A two-wire serial bus, with a data line (SDA) and a clock line (SCL), that lets a microcontroller talk to many chips, each with its own address. It is common for sensors, EEPROMs and small displays.
Where you use it
Pronounced 'I-squared-C' or 'I-two-C', and also written I²C. Both lines need pull-up resistors. Engineers talk about the device address, bus speed (100 kHz or 400 kHz), master and slave devices (now often called controller and target) and a device that doesn't acknowledge (NACK).
Examples
The temperature sensor doesn't respond on I2C; check that its address is 0x48.
We run the I2C bus at 400 kHz because the cable to the display is short.
Short for Serial Peripheral Interface: a fast synchronous serial bus with a clock line, two data lines and a separate chip-select line for each device. It is used for flash memory, displays and ADCs.
Where you use it
Pronounced 'S-P-I', sometimes 'spy'. The lines are usually called SCLK, MOSI, MISO and CS (chip select); newer documents may use SDO and SDI. Engineers talk about the SPI mode (clock polarity and phase), the SPI clock speed and pulling CS low to start a transfer.
Examples
The display runs on SPI at 20 MHz, so we can refresh it quickly.
The flash chip ignores our commands because the SPI mode is wrong.
A device or circuit that provides the voltage and current a system needs, usually by converting mains AC into a regulated DC output. A bench power supply is the adjustable unit on a lab desk.
Where you use it
Used in design and in the lab. You set the voltage and the current limit on a bench power supply, and choose a power supply for a product by output voltage, current, efficiency and certification. Often shortened to PSU; a switching power supply is called an SMPS.
Examples
Set the power supply to 12 V with a 500 mA current limit before you connect the board.
The power supply goes into protection mode every time the motor starts.
Common phrases
bench power supply · switching power supply · current limit · power supply unit · redundant power supply
A handheld or bench instrument that measures voltage, current and resistance, and often continuity, capacitance and frequency as well. It is the most basic tool for electrical testing.
Where you use it
Used every day by engineers and technicians. You set the multimeter to the right mode or range, connect the test leads and take a reading. A digital multimeter is called a DMM. To measure current you usually move the red lead to a separate A or mA jack.
Examples
Grab a multimeter and check the voltage on the 24 V terminals.
My multimeter reads 0.2 Ω with the leads touching, so I subtract that from the result.
Usage note
Leaving the red lead in the current (A) jack and then measuring voltage creates a short circuit through the meter. It is a classic and dangerous beginner mistake.
Common phrases
digital multimeter · test leads · take a reading · multimeter probes · set the range
An instrument that draws a voltage as a graph over time, so you can see the shape, size and timing of a signal. Engineers often just call it a scope.
Where you use it
Used to debug signals, power rails and communication lines. You set the timebase and the volts per division, adjust the trigger and capture a waveform. The key specifications are bandwidth, sample rate and the number of channels.
Examples
Put the oscilloscope on the clock line and see if there's any ringing.
We need an oscilloscope with at least 200 MHz of bandwidth for this board.
Usage note
The stress is on the second syllable: o-SIL-o-scope.
Common phrases
digital oscilloscope · oscilloscope probe · trigger level · capture a waveform · scope shot
A device that detects a physical quantity, such as temperature, pressure, light or current, and converts it into an electrical signal that a circuit can measure.
Where you use it
Used in measurement, automation and embedded systems. A sensor detects or measures something and gives an analog voltage, a 4–20 mA current loop or digital data as its output. Engineers talk about sensor range, accuracy, calibration and sensor failure.
Examples
The temperature sensor outputs 10 mV per degree Celsius.
The pressure sensor reads zero, so check its 4–20 mA loop first.
Common phrases
temperature sensor · current sensor · sensor output · proximity sensor · sensor reading
To find and fix the cause of a problem in a circuit, machine or system by checking it step by step. The related noun is troubleshooting.
Where you use it
Used every day in labs, factories and field service. Engineers troubleshoot a board, a panel or a fault, follow a troubleshooting guide and talk about troubleshooting steps. 'Debug' means much the same but is used more for firmware and electronics.
Examples
I spent the morning troubleshooting the conveyor panel; it turned out to be a loose wire.
Start troubleshooting at the power supply and work your way towards the outputs.
Common phrases
troubleshoot a fault · troubleshooting guide · troubleshooting steps · troubleshoot on site
The tip and lead that connect a measuring instrument, such as a multimeter or an oscilloscope, to the point you want to measure.
Where you use it
Used as a noun and a verb: you probe a signal, a pin or a test point. Oscilloscope probes have a ground lead and are often set to ×10; current probes clamp around a wire. Engineers talk about probe tips, probe compensation and probing a board.
Examples
Use the short ground spring on the probe, or you'll see ringing that isn't really there.
I probed the reset pin and it stays low the whole time.
Common phrases
oscilloscope probe · current probe · probe tip · ground lead · probe compensation
The process of comparing an instrument or sensor with a known reference and adjusting it or recording the results, so that its readings can be trusted.
Where you use it
Used in labs, production and quality systems. Instruments are 'due for calibration', 'in calibration' or 'out of calibration', and come with a calibration certificate. A calibration is 'traceable' when its references link back to national standards.
Examples
This multimeter is out of calibration, so don't use it for the acceptance test.
The current sensors need a calibration at zero and at full scale.
Common phrases
calibration certificate · due for calibration · out of calibration · calibration date
An unbroken electrical path between two points. A continuity test checks whether current can flow from one point to another, for example along a wire or a PCB trace.
Where you use it
Used in wiring checks and fault-finding. Most multimeters have a continuity mode that beeps when there is a low-resistance path. Technicians say 'check for continuity' or 'there's no continuity'. Continuity tests are done with the power off.
Examples
There's no continuity between the connector and the sensor, so the cable must be broken.
Put the meter in continuity mode and check each wire in the harness.
Common phrases
continuity test · check for continuity · continuity mode · no continuity
Short for printed circuit board: a flat board of insulating material with copper tracks that hold electronic components and connect them to each other.
Where you use it
Pronounced 'P-C-B'. Used in design and manufacturing: PCB layout, PCB design, PCB assembly (PCBA), a two-layer or four-layer PCB. You design a PCB in tools such as KiCad or Altium, send it for fabrication and then have it populated with components.
Examples
The first batch of PCBs arrived from the factory, but two footprints are wrong.
We moved to a four-layer PCB to get a solid ground plane.
To join metal parts, such as a component lead and a copper pad, by melting a low-temperature metal alloy between them. The alloy itself is also called solder.
Where you use it
Used daily in labs and production. You solder a component, a wire or a connector, and talk about the soldering iron, flux, a solder joint, a dry joint and lead-free solder. To remove a part you desolder it.
Examples
Can you solder these two wires to the connector before the test?
The connector wasn't soldered properly, so the joint cracked.
Usage note
In American English the 'l' is silent: 'SOD-er'. In British English it is usually pronounced: 'SOL-der'.
Common phrases
solder joint · soldering iron · lead-free solder · solder a component · solder bridge
A copper line on a PCB that carries current or a signal between pads, working like a flat wire. British engineers often call it a track.
Where you use it
Used in PCB layout and repair. You route, widen, shorten or cut a trace, and talk about trace width, trace length, power traces and broken traces. The width of a trace depends on the current it carries and the copper thickness.
Examples
This trace is too thin for 3 A; make it at least 1.5 mm wide.
We cut the trace and added a jumper wire to fix the prototype.
Common phrases
trace width · route a trace · cut a trace · power trace · signal trace
A small plated hole in a PCB that connects a trace or copper area on one layer to another layer.
Where you use it
Used in multilayer PCB design. Engineers place or add vias, talk about via size and drill size, and distinguish through-hole vias from blind and buried vias. Groups of vias under hot components carry heat to other layers and are called thermal vias.
Examples
Put a via next to each decoupling capacitor to reach the ground plane.
Blind vias would make the board much more expensive.
Usage note
Both 'VY-uh' and 'VEE-uh' are common pronunciations. The plural is vias.
Common phrases
through-hole via · blind via · thermal via · via size · add a via
The pattern of copper pads, holes and markings on a PCB that matches a component's package, so that the part can be placed and soldered correctly.
Where you use it
Used in PCB libraries and manufacturing. Engineers create, check, assign or fix a footprint, and a wrong footprint is a common reason for a board respin. Footprints usually follow the land pattern the manufacturer recommends in the datasheet.
Examples
The regulator's footprint is mirrored, so the part can't be soldered.
Double-check every new footprint against the datasheet before you order the boards.
Short for bill of materials: the full list of parts needed to build a product, with part numbers, quantities, reference designators and approved suppliers.
Where you use it
Pronounced 'B-O-M' or 'bom'. Exported from the design tool and sent with the Gerber files for assembly. Engineers update, review and cost the BOM, and talk about BOM cost, BOM lines and second-source alternatives for parts that are hard to find.
Examples
The BOM still lists the old capacitor; please update it before we send it to the assembler.
We cut the BOM cost by 12% by switching to a cheaper microcontroller.
Common phrases
BOM cost · update the BOM · BOM line · export the BOM
Short for surface-mount device: a component soldered directly onto pads on the surface of a PCB, without leads going through holes. The technology is called SMT.
Where you use it
Used in PCB design and assembly. SMD parts come in package sizes such as 0402, 0603 and 0805 (imperial codes), are placed by pick-and-place machines and are soldered in a reflow oven. The alternative is through-hole (THT) components.
Examples
All the passives are 0402 SMD parts, which are hard to solder by hand.
We moved from through-hole to SMD components to make the board smaller.
Usage note
Strictly, SMD is the component and SMT (surface-mount technology) is the process, but many people use the two interchangeably.
The standard set of files sent to a PCB manufacturer, with one file for each copper layer, the solder mask, the silkscreen and the board outline, usually together with a drill file.
Where you use it
Used whenever a board goes to fabrication. Engineers generate the Gerber files in the design tool, check them in a Gerber viewer and send them to the manufacturer as a zip file. Newer formats such as ODB++ and IPC-2581 exist, but Gerber is still the most common.
Examples
Send the Gerber files and the drill file to the factory today so we get the boards next week.
Always check the Gerber files in a viewer before you place the order.
Common phrases
export the Gerber files · Gerber viewer · drill file · send the Gerbers
A large, continuous area of copper on a PCB layer that is connected to ground. It gives signals a short, low-impedance return path and helps reduce noise.
Where you use it
Used in PCB layout and EMC discussions. Engineers keep the ground plane solid, avoid splitting it, connect parts to it with vias and route fast signals directly over it. In a four-layer board, one inner layer is usually a ground plane.
Examples
The slot in the ground plane forces the return current to take a long detour.
Layer 2 is a solid ground plane under all the high-speed signals.
The common reference point of a circuit, taken as 0 V, or a safety connection to the earth. In electronics it is marked GND; in installations it is the protective earth conductor.
Where you use it
Used as a noun and a verb: connect to ground, a ground wire, a ground fault, the chassis is grounded. American English says ground, while British English and IEC texts usually say earth. In electronics, ground often just means the 0 V return path.
Examples
Connect the black probe to ground and measure the 3.3 V rail.
The metal enclosure is connected to ground with a green-yellow wire.
Usage note
In Turkish, 'toprak' is the safety earth and 'şase' usually means the circuit's 0 V point or the metal chassis. English uses ground (US) or earth (UK) for both.
Common phrases
ground wire · ground fault · ground loop · connect to ground · signal ground
An automatic switch that opens a circuit when it detects too much current, for example from an overload or a short circuit. Unlike a fuse, it can be reset and used again.
Where you use it
Often just called a breaker. A breaker 'trips', and you reset it or switch it back on. Types include the MCB (miniature circuit breaker), the MCCB (moulded case circuit breaker) and the ACB (air circuit breaker) used in large panels.
Examples
The circuit breaker trips every time we start the welding machine.
Switch off the circuit breaker for the lighting before you replace the fitting.
Usage note
Turkish 'sigorta' is used for both breakers and fuses. In English they are different: a fuse melts and has to be replaced, while a circuit breaker trips and is reset.
Common phrases
the breaker tripped · reset a circuit breaker · miniature circuit breaker · breaker rating · switch off the breaker
A safety device with a thin metal link that melts and breaks the circuit when the current is too high. Once it has blown, it has to be replaced.
Where you use it
A fuse 'blows' and you replace it. Engineers talk about the fuse rating (for example 2 A or 10 A), fast-acting and slow-blow (time-delay) fuses and fuse holders. Fuses are common inside equipment, in vehicles and in high-power circuits.
Examples
The fuse blew again, so there must be a fault somewhere downstream.
Replace it with a fuse of the same rating, not a bigger one.
Common phrases
the fuse blew · replace a fuse · fuse rating · slow-blow fuse · fuse holder
A single conductor, usually copper, often covered with insulation. A cable is several insulated wires grouped together inside an outer sheath.
Where you use it
Used as a noun and a verb: you wire a panel, wire up a circuit, strip a wire or crimp it. Wire size is given in mm² in Turkey and Europe and in AWG in the US. Common terms are live wire, ground wire, solid wire and stranded wire.
Examples
Use 2.5 mm² wire for the socket circuits.
One of the wires came loose from the terminal and the machine stopped.
Usage note
Turkish 'kablo' covers both wire and cable. In English a wire is a single conductor, while a cable has several insulated conductors inside a sheath.
Common phrases
strip a wire · stranded wire · live wire · wire size · wire up
Non-conducting material, such as PVC or rubber, that covers conductors and keeps current where it should be. Good insulation protects people from shock and prevents short circuits.
Where you use it
Used in installation, testing and maintenance. Insulation can be damaged, worn or melted, or it can break down. The insulation resistance test, often done with a megohmmeter ('megger'), checks that insulation is still in good condition.
Examples
The insulation on this cable is cracked, so it has to be replaced.
We measured the motor's insulation resistance before putting it back into service.
Usage note
Turkish 'izolasyon' usually means insulation. English 'isolation' is different: it means separating a circuit from a source, as in 'isolate the supply' or 'galvanic isolation'.
Common phrases
insulation resistance · damaged insulation · insulation test · insulation class · cable insulation
The conductor that carries current back to the source in an AC system and is normally close to earth potential. In IEC wiring it is blue; in North America it is white.
Where you use it
Used in installation and fault-finding. Electricians talk about the neutral wire, the neutral conductor, the neutral bar and a broken or lost neutral. Under normal conditions neutral is close to 0 V, but it still carries current and is treated as potentially live.
Examples
A loose neutral in the panel made the voltage on some sockets rise to 300 V.
Connect the blue wire to the neutral terminal.
Usage note
Neutral and ground (earth) are not the same: neutral carries the normal return current, while the protective earth carries current only during a fault.
Common phrases
neutral wire · neutral conductor · neutral bar · broken neutral · phase and neutral
The effect of electric current passing through the body when a person touches a live part. It can cause burns, muscle spasms or heart rhythm problems, and it can be fatal.
Where you use it
Used in safety training, risk assessments and accident reports. People get or receive an electric shock, and equipment is designed to protect against it. Standards talk about protection against electric shock, touch voltage, and direct and indirect contact.
Examples
The technician got an electric shock from a capacitor that was still charged.
The RCD protects people against electric shock if the insulation fails.
Usage note
'Electrocuted' traditionally means killed by electricity, so careful writers say someone 'got a shock' when the accident was not fatal.
Common phrases
get an electric shock · risk of electric shock · protection against electric shock · touch voltage
A safety procedure in which energy sources are switched off and isolated, then locked and tagged so that nobody can turn them back on while work is being done. It is often shortened to LOTO.
Where you use it
Used in factories, plants and maintenance teams. Workers apply lockout/tagout, put their own lock and tag on an isolator and verify that the equipment is de-energized before they start. The steps for each machine are written in a LOTO procedure.
Examples
Apply lockout/tagout on the main isolator before anyone opens the conveyor panel.
Each technician puts their own lock on the lockout/tagout point.
A sudden, extremely hot burst of light and energy caused by an electric arc between conductors or to ground. It can cause severe burns, blinding light and a pressure blast.
Where you use it
Used in electrical safety, especially for work on switchgear and panels. Engineers carry out an arc flash study and label equipment with the incident energy, and workers wear arc-rated PPE. The arc flash boundary is the distance within which burns are possible.
Examples
The arc flash label on the switchboard shows an incident energy of 8 cal/cm².
Racking out a breaker is a high-risk task for arc flash.
Common phrases
arc flash hazard · arc flash study · arc flash boundary · arc-rated PPE
Short for residual current device: a protective device that switches off a circuit when it detects current leaking to earth, for example through damaged insulation or a person. 30 mA devices are common for protecting people.
Where you use it
Used in building installations and on construction sites. An RCD trips, and its test button is pressed regularly to check it. Related names are RCCB, RCBO (with overcurrent protection) and, in North America, GFCI. Engineers talk about the RCD rating and nuisance tripping.
Examples
The RCD trips whenever the washing machine starts heating, so its heater may be leaking.
Press the test button on the RCD to make sure it still works.
Common phrases
RCD trips · 30 mA RCD · RCD test button · nuisance tripping
A condition in which a circuit, cable or machine carries more current or power than it is rated for over a period of time. Unlike a short circuit, it builds up heat gradually.
Where you use it
Used as a noun and a verb: a circuit is overloaded, a motor trips on overload. Engineers talk about overload protection, thermal overload relays on motors and overload capacity. Breakers react slowly to small overloads and quickly to short circuits.
Examples
The conveyor motor tripped on overload because the belt was jammed.
Running all three heaters from one socket will overload the circuit.
An enclosure that divides an incoming supply into separate circuits, each protected by its own breaker or fuse. In North America it is usually called a panelboard or breaker panel.
Where you use it
Used in buildings and industrial installations, and often shortened to DB. Electricians install, wire, label and test a distribution board. In UK homes it is called a consumer unit. Larger industrial versions include the main distribution board (MDB) and the motor control centre (MCC).
Examples
Label every breaker in the distribution board so the next person knows what it feeds.
The second-floor distribution board is fed from the main panel in the basement.
Common phrases
main distribution board · sub-distribution board · consumer unit · panel schedule
A drawing that shows how the components of a circuit are connected, using standard symbols instead of their real shape or position on the board.
Where you use it
Used as a noun ('the schematic') and as an adjective ('schematic diagram'). Engineers draw, review and update the schematic, then create the PCB layout from it. Components carry reference designators like R1, C5 or U3, and the schematic is the first document you open when troubleshooting a board.
Examples
According to the schematic, pin 4 should go to the reset line.
Please send me the latest schematic before the design review.
Common phrases
schematic diagram · draw a schematic · schematic review · schematic symbol · schematic capture
A document from the manufacturer that gives a component's specifications: ratings, electrical characteristics, pin descriptions, package drawings and typical application circuits.
Where you use it
Read every day when choosing and using parts. Engineers 'check the datasheet', look up the pinout, the absolute maximum ratings and the recommended operating conditions, and quote values 'from the datasheet'. Also spelled 'data sheet'.
Examples
According to the datasheet, the maximum input voltage is 36 V.
Check the datasheet for the recommended layout around the regulator.
Usage note
The 'absolute maximum ratings' in a datasheet are damage limits, not normal operating values; designers stay within the 'recommended operating conditions'.
Common phrases
check the datasheet · absolute maximum ratings · pinout · typical application · electrical characteristics
The maximum voltage, current, power or temperature that a device is designed to handle safely in normal use, as stated by the manufacturer. Rated values appear on nameplates and in datasheets.
Where you use it
Used constantly with numbers: a 16 A rating, a 600 V rating, an IP65 rating. Engineers check that every part is 'rated for' the application and talk about rated voltage, rated current and power rating. Derating means using a part below its full rating for safety or longer life.
Examples
The connector has a current rating of only 3 A, but the heater draws 5 A.
Check the voltage rating of the capacitor before you use it on the 48 V rail.
Common phrases
current rating · voltage rating · power rating · rated current · IP rating
A drawing that shows the physical connections of an installation or machine: which wire goes to which terminal, with wire numbers, colors and connector pins.
Where you use it
Used by electricians, panel builders and service technicians. A wiring diagram is closer to the real layout than a schematic. People follow, check, update or mark up the wiring diagram, and a printed copy is often kept inside the panel door.
Examples
According to the wiring diagram, wire 23 should land on terminal X1:5.
Update the wiring diagram after you add the new sensor.
Common phrases
follow the wiring diagram · panel wiring diagram · terminal number · wire number
A simplified drawing of a power system in which one line represents all the conductors of a circuit. It shows sources, transformers, breakers, busbars and loads, and how they are connected.
Where you use it
Used in power design, substations, data centres and industrial plants. Often shortened to SLD, and called a one-line diagram in the US. Engineers review the single-line diagram before any design change, and it is the starting point for short-circuit and protection studies.
Examples
Check the single-line diagram to see which breaker feeds the chiller.
The single-line diagram shows two transformers feeding the main busbar.
Short for electromagnetic compatibility: the ability of a device to work properly in its electromagnetic environment without disturbing other equipment or being disturbed by it.
Where you use it
Used in product design, testing and certification. EMC has two sides: emissions (what the product sends out) and immunity (how well it resists disturbances). Products pass or fail EMC testing in an accredited lab, and EMC is a key part of meeting the CE marking requirements in Europe.
Examples
The prototype failed the EMC test because of emissions from the switching supply.
Think about EMC early: a good ground plane and short current loops cost less than shielding later.
Usage note
EMI (electromagnetic interference) is the problem itself; EMC is the goal of a design that avoids causing or suffering from it.
Short for International Electrotechnical Commission: the global organization, founded in 1906 and based in Geneva, that publishes international standards for electrical and electronic technologies.
Where you use it
Pronounced 'I-E-C'. Used when citing standards, such as IEC 60364 for low-voltage installations or IEC 61010 for the safety of measuring equipment. Many European (EN) and Turkish (TS EN) standards are based on IEC standards. In North America, NEC, UL and IEEE documents are used more often.
Examples
The panel was designed and tested according to IEC 61439.
Our customer in the US asked for UL certification instead of IEC compliance.
Common phrases
IEC standard · comply with IEC · IEC symbols · IEC 60364
Ten questions from this glossary. Pick the right meaning for each term and see your score.
How to learn electrical & electronics engineering vocabulary
Read real texts from the field: component datasheets, application notes, equipment manuals, standards and test reports use this vocabulary in its natural context.
Learn each term with the words that usually go with it: not just 'fuse' but 'the fuse blew', 'replace a fuse' and 'fuse rating'; not just 'breaker' but 'the breaker tripped'.
Practice reading values and units aloud the way engineers do: 'four point seven kilohms', 'a hundred nanofarads', 'three point three volts', 'two hundred thirty volts AC'. English uses a decimal point, not a comma.
Keep a list of words that look or sound like Turkish but work differently in English, such as insulation (yalıtım) and isolation (ayırma), or resistance (the property) and resistor (the part), which are both 'direnç' in Turkish.
Describe a measurement or a fault in a few short English sentences, the way you would in a test report or a message to a colleague: what you measured, where, and what you expected.
Frequently asked questions
How can I learn English for electrical and electronics engineering?
Read real texts from the field and notice how the words are used: datasheets, application notes, standards, manuals and test reports. Learn each term with its usual partners (measure the voltage, the breaker tripped, solder a connector) and use new words right away in your own reports, emails and design reviews.
Which electrical and electronics terms should I learn first?
Start with the words you meet in every lab and on every drawing: voltage, current, resistance, power, circuit, short circuit, resistor, capacitor, diode, transistor, ground, AC and DC, multimeter, oscilloscope, PCB, schematic and datasheet. Then move on to power systems, signals, microcontrollers, PCB design and safety. The terms in this glossary follow the same order, from most to least essential.
Should I say 'ground' or 'earth'?
Both are correct. American English uses ground (ground wire, ground fault), while British English and many IEC documents use earth (earth wire, earth fault). In electronics, ground or GND is also used for the 0 V reference of a circuit, even when nothing is connected to the real earth. Follow the style of the standard or the customer you are writing for.
How do I read component values like 4k7 or a capacitor marked 104?
In 4k7 the letter replaces the decimal point, so it means 4.7 kΩ and is read 'four point seven K' or 'four point seven kilohms'. On small capacitors, the first two digits are the value and the third is the number of zeros in picofarads, so 104 means 100,000 pF, which is 100 nF, read 'a hundred nanofarads' or 'point one microfarad'.
