800+ Electrical & Electronic Abbreviations with Full Forms. A-Z

Electrical and Electronics Engineering Abbreviations with Full Forms

Below is the list of 800+ short form or abbreviation with full form used in electrical and electronic engineering. All the abreavtion are listed from A to Z and Numerical form in Ascending form. You can press “CTRL + F” and write the short form or paste in search box to go to the exact matching abbreviation with full form.

Related Post: Electrical and Electronic Engineering Symbols

Electrical and Electronic Engineering Abbreviations with Full Forms

A Amperes, amps.
A_pp Peak-to-peak amperes
AA Anti-Aliasing
AAAC All Aluminum Alloy Conductor
AAC All Aluminum Conductor
AACSR Aluminum Alloy Conductor Steel Reinforced
AAF Anti-Aliasing Filter
ABC Aerial Bundled Conductors or Cables
AB switch Air Break switch
AC Alternating current or voltage
A/C Air Conditioning
ACAR Aluminum Conductor Alloy Reinforced
ACB Air Circuit Breaker
ACCB Air Case Circuit Breaker
ACDB Alternating Current Distribution Board
ACSR Aluminum Conductor Steel Reinforced
ACVS Air Conditioning & Ventilation System
ADC Analog to Digital Converter
AF Audio Frequency or Audible Frequency
AFC Automated Frequency Control
AFC Available Fault Current
AFCB Arc Fault Circuit Breaker
AFCI Arc Fault Circuit Interrupter
AFL Amps Full Load
AFT Automatic Fine Tuning
AGC Automatic Gain Control
AGME American Gear Manufacturer’s Association
AGPS Assisted (or Aided) GPS
AH Ampere-Hour Capacity of Batteries.
AHU Air Handling Unit
AI Analog Input
AI Artificial Intelligence
AIC Ampere Interrupting Capacity
AL Aluminum
ALCI Appliance Leakage Current Interrupter
ALTC Automatic Load Tap Changing
ALU Arithmetic and Logic Unit
AMOLED Active Matrix Organic Light Emitting Diode
ANSI American National Standards Institute.
AO Analog Output
AoA Angle of Arrival
AOI Automatic Optical Inspection
AP Access Point
APD Avalanche Photo Diode
APFC Automatic Power Factor Control
API American Petroleum Institute, Application Program Interface
ARM Advanced Reduced instruction set computing Machine
ARMS Arc Flash Reduction Maintenance Switch
ASCII American Standard Code for Information Interchange
ASIC Application Specific Integrated Circuit
ASK Amplitude Shift Keying
ASME American Society for Testing and Materials
ASP Application Service Provider
ASTA Association of Short-circuit Testing Authorities.
ATS Automatic Transfer Switch
ATC Automatic Temperature Control
ATMega Microcontroller Cip created by Atmel in the megaAVR family
ATMEL Advanced Technology for Memory and Logic
AV Audio/video
AVO-M Ampere-Volt-Ohm Meter
AVR Automatic Voltage Regulator
AWA Aluminum Wire Armour
AWG American Wire Gauge

B or b Electrical Susceptance
Bar or bar Pressure in atmospheres.
BASEEFA British Approvals Service for Electrical Equipment in Flammable Atmospheres
BBM Break before Make
BCD Binary Coded Decimal
BCR Backspace card reader and Barcode reader
BER Bit Error Rate
BEV Billion Electron Volts
BGA Ball Grid Array
BIL Breakdown insulation level
BJT Bipolar Junction Transistor
BLAC Brushless AC
BLDC Brushless DC
BLDMBrushless DC Motor
BOM Bill Of Materials
BPF Band Pass Filter
bps Bit per second
Bps Byte per second
BSI, BS, CP British Standards Institution, or its publications
BTS Base Transceiver Station
BTU British thermal unit
BW Bandwidth, (difference between upper and lower limits of a band of frequencies)

C Electrical capacitance, Conduit
CA Criticality Analysis
CAAPS Circuit Assembly And Processing System
CACA Totally enclosed air circuit, air cooled.
CACW Totally enclosed air circuit, water cooled.
CAD Computer aided design.
CAN Controller area network
CATV Cable Television or Community Antennae Television
CB Circuit breaker
CBCU Circuit breaker control unit.
CBI Complementary Binary, referring to a system of codes
CBM Certified Ballast Manufacturer
CBR Constant Bit Rate
CC Constant Current
CCCS Current Controlled Current Source
CCD Charge-Coupled Device
CCR Central control room
CCT Circuit (also: CIR, CKT)
CCTV Closed Circuit Television
CCU Central control unit
CD Candela
CDMA Code Division Multiple Access
CEGB Central Electricity Generating Board (UK)
CENELEC European Committee for Electro technical Standardization
cont. Continuous quantity
CFL Compact Fluorescent Light or Compact Fluorescent Lamp
CG Cable Glands
CIR Circuit (also: CCT, CKT)
CISC Complex Instruction Set Computer
CKT Circuit (also: CCT, CIR)
CLF Current Limiting Fuse
CMOS Complementary Metal – Oxide Semiconductor
CMRR Common Mode Rejection Ratio
CNC Computer Numeric Control
COG Chip-on-glass
COR CU Corrugated Copper.
Cosθ Power factor.
CPLD Complex Programmable Logic Device
CPT Control Power Transformer
CPU Central Processing Unit
CRO Cathode Ray Oscilloscope
CRT Cathode Ray Tube
CSA, csa Cross-Sectional Area
CSI Current Source Inverter
CSP Chloro Sulphonated Polyethylene
CSS Computerized Synchronizing System
CT Current Transformer
CU Un-tinned Copper
CUWB Copper Wire Braid
CVT Constant Voltage Transformer

d Day.
DAC Digital to Analog Converter
db(A) Measurement unit of sound, Decibels, absolute.
dBm Unit level for power ratio expressed in decibels (dB) with reference to one mill watt (mW)
DB Distribution Board
DC Direct Current or Voltage
DCDB Direct Current Distribution Board
DCS Distributed Control System
DE Drive End of a shaft
DEMUX Demultiplexer, Single input into multiple outputs
DFT Discrete Fourier Transform
DIA Diameter
DIMM Dual-In-line Memory Module
DIN Deutsches Institut für Normung means German Institute for Standardization
DIP Dual-in-Line Package
DIPS Dual-In-Line Sockets
DLD Digital Logic Design
DLL Delay Locked Loop
DMA Direct Memory Access
DMM Digital Multimeter
DMS Data management system
DMT Definite minimum time
DNC Do Not Connect
DO fuse Drop Out Fuse
DOL Direct-on-line starting of induction motors.
DOS Disk Operating System
DP Double Pole or Distribution Panel
DPDT Double Pole, Double Throw
DPI Dots Per Inch
DPIC Double Pole Iron Clad
DPM Digital panel meter
DPR Dividing Pulse Relay
DPST Double Pole, Single Throw
DRAM Dynamic Random Access Memory
DRC Design Rule Checking
DSP Differential Signal Processing
DTMF Dual Tone Multi-Frequency
DTL Diode Transistor Logic
DTSP Discrete Time Signal Processing
DUT Device Under Test
DVM Digital Volt Meter
DWR Divided winding rotor synchronous generator.

EEarth or ground
EB Equipment Branch
EBIC Electron-Beam-Induced Current
EC Electrical Code or Electrical Contractor or Electronic Commutator
ECAD Electronic Computer-Aided Design
ECHA Equipment certified for hazardous areas.
ECL Emitter coupled logic
EEC European Economic Community
EEMVA Engineering Equipment and Materials Users Association
EEPROM Electrically Erasable Programmable Read-Only Memory
EF Exhaust Fan
EFT Electrical fast transient
EHT Extra High Tension
EHV Extra high voltage
EIEMA Electrical Installation Equipment Manufacturer’s Association (UK)
ELCB Earth Leakage Circuit Breaker
ELDC Electric Double-Layer Capacitors (supercap)
ELEV Elevator
ELV Extra low voltage, less than 51 volts
EM Emergency
EMA Ethylene methyl acrylate
EMC Electromagnetic compatibility
EMI Electromagnetic interference
EMF,e.m.f.Electromotive force
EMLDB Emergency Lighting Distribution Board
EMR Electro Mechanical Relay
EMT Electrical Metallic Tubing
EOCR Electronic Overcurrent Relay
EOS Electrical Over Stress
EP Emergency Power
EPDM Ethylene propylene diene monomer
EPO Emergency Power Off (Button or Switch)
EPR Ethylene propylene rubber
EPROM Erasable Programmable Read-Only Memory
ERA Electrical Research Association (UK)
ERM Electronic restart module
ESD Emergency shutdown, Electrostatic discharge
ESL Equivalent Series Inductance
ESP Electric submersible pump
ESR Equivalent Series Resistance
EST Extra Super Tension
Ex (), Ex ‘ ’ Certification symbol for hazardous area equipment.
EEx (), EEx ‘ ’ Certification symbol for hazardous area equipment, with European harmonisation of standards.
EV Electron volt, a unit of energy similar to joules
EWC Electric Water Cooler
EWS Engineering work station.

F, f or Hz Frequency, Fuse, Farad
FAFire Alarm
FAA Fire Alarm Annunciator
FAT Factory acceptance testing
FBA Factory built assemblies.
FBT Fly back Transformer
FCEV Fuel Cell Electric Vehicle
FCU Feeder control unit.
FDM Frequency Division Multiplexing
FDNR Frequency Dependent Negative Resistor
F and G Fire and Gas
FEED Front-end engineering and design of a project.
FET Field Effect Transistor
FFC Flexible Flat Cable
FFT Fast Fourier Transform
FIFO First-In, First-Out (a queue)
FILO First-In, Last-Out (a stack)
FLA Full Load Amperes
Flex Flexible, used for cables.
FM Frequency Modulation
FMC Flexible Metal Conduit
FPGA Field-Programmable Gate Array
Freq Frequency
FRLS Fire Resistance Low Smoke
FSC Final Sub Circuit
FSM Finite State Machine
FSK Frequency Shift Keying
FVC Frequency to Voltage Converter

G or g Electrical conductance, or ground
GBW Gain Bandwidth Product
GCB Gas circuit breaker.
GCP Generator control panel.
GFCI Ground Fault Circuit Interrupter
GFI Ground Fault Interrupter
GIC Generalized Impedance Converter
GIS Gas insulated switchgear.
gm Transconductance
GND Ground
GO Gang Operated
GOR Gas to oil ratio of oil well fluids
GOS Group Operated Switches
GPIO General Purpose Input / Output
GPRS General Packet Radio Service
GPS Global Positioning System
GRMC Galvanized Rigid Metal Conduit
GRP Glass reinforced plastic.
GSM Global System for Mobile Communications
GSWA Galvanized steel wire armour
GSWB Galvanized steel wire braid.
GTG or GT Gas-turbine generator
GTO Gate turn off thyristor
GUI Graphic User Interface

h or hr Hour.
HART Highway Addressable Remote Transducer
HBT Heterojunction bipolar transistor
HCL Hydrogen chloride, gas or acid
HDMI High-Definition Multimedia Interface
HED Hall Effect Device
HEMT High-electron-mobility transistor
HF High frequency
hFE Large-signal current gain of a BJT
HMI Human Machine Interface
HOA Hand-Off-Automatic Switch
HOFR Heat and oil resisting, flame retardant.
Hp Horse power, unit of power in fps system
HPF High Pass Filter
HRC High rupturing capacity
HT High Tension
HTS High-temperature semiconductor
HUI Human User Interface
HV High voltage, above 600 volts
HVAC Heating ventilation and air conditioning
Hz Frequency in cycles per second, or hertz

I Current in amperes
IAC or Iac Alternating current
IALA International Association of Lighthouse Authorities
IC Integrated circuit
ICDB Iron Clad Distribution Board
ICI Imperial Chemical Industries plc (UK)
ICSP In Circuit Serial Programming
ICTP Iron Clad Triple Pole
IDC, Idc Direct current
IDMT Inverse definite minimum time
IEC International Electrotechnical Commission
IEE Institution of Electrical Engineers of UK
IEEE Institute of Electronic and Electrical Engineers of USA
IF Intermediate Frequency
IFT Inverse Fourier Transform
IG Isolated Ground
IGBT Insulated-gate Bipolar Transistor
IGFET Insulated Gate Field Effect Transistor
I/O Input or output signals or quantity
IOT Internet of Things
IMO International Maritime Organization
IMC Intermediate Metal Conduit
IMCS Integrated motor control system
IMS Information management system
inst. Instantaneous quantity
INT Interlock
int. Intermittent quantity
IP Institute of Petroleum (UK) and its publications
IP Ingress protection code, see IEC60529
IPMSM Interior Permanent Magnet Synchronous Motor
IRInsulation resistance
IS Intrinsically safe signal, circuit or equipment
Is/In, IS/IN Ratio of starting current to running current
ISO International Standards Organization
ISP Internet Service Provider
ITU International Telecommunication Union

J Energy in joules or newton-meters
J Current density, amps/mm2
JB Junction Box
JFET Junction field effect transistor
JEDEC Joint Electron Device Engineering Council

kA Kilo-amperes
KCL Kirchhoff’s Current Law
KCMIL Thousand Circular Mils
KEMA Short circuit testing authority in The Netherlands
kg Kilogram.
km Length in kilometers
kpm Kilometers per hour.
kV, Ku Kilo-volts.
kVA Kilo-volt-amperes.
kVAr Reactive kilo-volt-amperes.
KVL Kirchhoff’s Voltage Law
kW Kilowatts.
KWH Kilo Watt Hour

L Electrical inductance in henries
L Line (Phase, Live or Hot) or local control operation
LA Lightning Arrester
LAN Local area network
lbs Weight of a substance in pounds.
LCD Liquid-crystal display
LDB Lighting Distribution Board
LDR Light Dependent Resistor
LDS Low density foam
LED Light emitting diode
LEL Lower explosive limit
LF Low frequency
LFMC Liquid Tight Flexible Metal Conduit
LHS Left-hand side
Li–ion Lithium Ion, a type of rechargeable battery
Lloyds Lloyds Register of Shipping (UK)
LMS Load management system
LNA Low noise amplifier
LNG Liquefied natural gas
loc or (L) Local operation
LOP Loss of power
LOPT Line Output Transformer
LOS Loss of signal
LPF Low Pass Filter
LPG Liquefied petroleum gas
LPS Lightning Protection System
LRA Locked Rotor Amperes
LSB Least Significant Bit
LSDS, LSS Load shedding system
LSF Low smoke and fumes, applied to cables and wires.
LSI Large-scale integration
LSLH Low smoke low halogen
LSRS, LSR Load sharing system
LT Low Tension
LTG Lighting
LV Low voltage, 50 to 600 volts
LVDT Linear Variable Differential Transformer
L1, L2, L3,N Notation for line and neutral voltages and currents.
LUT Look Up Table
LUX Level of illumination
LVDT Linear Variable Differential Transformer

m Length or dimension in meters, or month
mA Current in milli-amperes
MAD Mean Annual Discharge
man or (M) Manual operation
mbar Milli-bar
MB High-pressure mercury, without phosphor coating
MB Megabyte, a computer date storage unit
MBB Make-before-break
MBF High-pressure mercury, with phosphor coating
MBFR High-pressure mercury, with phosphor coating and internal reflector
MBI High-pressure discharge with metallic halides
MBIF High-pressure discharge with metallic halides, with phosphor coating
MBR Double-ended linear arc tube
MBTF Combination of MBF lamp and a filament lamp
MC Metal Clad Cable
MCB Miniature circuit breaker.
MCC Motor control center
MCCB Moulded case circuit breaker
MCM Multi-Chip Module
MCP Motor Circuit Protection
MCR Maximum continuous rating
MCU Motor control unit
MCuMicrocontroller
MDB Main Distribution Board
MEC Micro Energy Cell
MEMS Micro ElectroMechanical Systems
MESFET Metal-Semiconductor Field-Effect-Transistor
MESG Maximum experimental safe gap
MF Multiplying Factor
MFSK Multiple frequency-shift keying
Mho Unit of electrical admittance
MI Mineral Insulated
MIC Minimum ignition current
MICC Mineral insulated calendar cable
MIDI Musical Instrument Digital Interface
MIMIC Mimic display panel
MISO Master Input Slave Output
MLDB Main Lighting Distribution Board
MLO Main Lugs Only
mm Length or dimension in millimeters
MMF, mmf Magneto-motive force
MMI Man–machine interface.
MMSCF Million standard cubic feet of a gas
Mole% Molecular weight in %
MOSFET Metal Oxide Semiconductor Field Effect Transistor
MOSI Master Output Slave Input
MOV Metal oxide varistor
MPCB Motor Protection Circuit Breaker
MPDB Main Power Distribution Board
MPPT Maximum Power Point Tracking
MPU Microprocessor
MS Main Switch
MSB Most Significant Bit
MSW Module steelwork
MT Mica glass tape
MTBF Mean time between failures
MTTR Mean time to repair
MUX Multiplexer, several analog or digital inputs into single output
MV Medium voltage
mV Voltage in millivolts
MVA Mega-volt-amperes
MVAr Reactive mega-volt-amperes
MW Megawatts

N or n Number of items e.g. generators installed
N or n Number of turns in a winding
N or n Neutral terminal or line Neutral
NACE National Association of Corrosion Engineers (USA)
NBR Nitrile butadiene rubber
NC, N/C Normally closed switching device, No Connection
NCT Neutral Current Transformer
NDE Non-drive end of a shaft.
NEC National Electric Code (USA)
NEMA The National Electrical Manufacturer’s Association (USA)
NER Neutral earth resistor.
NFPA National Fire Protection Association (USA)
Ni Nickel metal
NL Neutral Link, Night Light
NO, N/O Normally open switching device
NOx Nitrogen based gas emissions.
NPR Noise-power ratio
NPT National pipe threads (USA).
NRZ Non Return to Zero
NS Used to describe a type of variable speed AC motor
NTC Negative Temperature Coefficient
NTS Not to scale
NVM Non Volatile Memory

O Open, off or stop
OC, O/COvercurrent or open circuit
OCB Oil circuit breaker
OCTC On-circuit Tap Changer
OCV Open Circuit Voltage, the difference in electrical potential when disconnected from a circuit
OF, O/F Over frequency
OFAF Forced circulation of internal liquid, forced heat exchanging to external air.
OFAN Forced circulation of internal liquid, natural heat exchanging to external air.
OHL, OHLineOverhead line
Ohms Unit of electrical resistance or impedance
OIM Offshore installation manager
OL, O/L Overload
OLED Organic light-emitting diode
OLP OverLoad Protection
OLR OverLoad Relay
OLTC On-load Tap Changer
ONAF Naturally circulated internal liquid, forced heat exchanging to external air
ONAN Naturally circulated internal liquid, natural heat exchanging to external air
OpAmp Operational Amplifier
OSC Oscillator
OSHA Occupational Health and Safety Administration (USA)
OTA Operational Transconductance Amplifier
OV, O/V Overvoltage.
OVP Overvoltage Protector

P or WActive power, watts, Pole
p, s Laplace operator in mathematics, for transfer functions
P & ID Piping and instrument diagram
PA Public address system
PAL Programmable Array Logic
PAM Pulse or pole amplitude modulation
PB Push Button or Panic Button or Pull Box
PB, Pb Lead metal
PBWB Phosphor bronze wire braid
PBCU, TCU Tinned copper
PC Programmable controller, Program counter; used in microcontroller
PCB Printed circuit board
PCC Point of common connection, Power Control Centre
PCM Pulse-code modulation
PDA Personal digital assistant
PDB Power Distribution Board
PDM Pulse density modulation
PDP Power Distribution Panel
PEC PhotoElectric Cell
PELV An extra-low voltage system similar to SELV but connected to earth at some point
PF, pf Power factor
PFD Phase/frequency detector
PFM Pulse Frequency Modulation
PGA Programmable Gain Amplifier
Ph, ph Phases of an electrical circuit
PID Proportional, Integral, Derivative. A type of controller used in control systems
PIR Passive Infrared Sensors
PIV Peak Inverse Voltage
pk, peakPeak value of an instantaneous quantity
PLA Programmable logic array
PLC Programmable logic controller
PLCC Plastic Leaded Chip Carrier
PLL Phase-Locked Loop
PM Permanent Magnet
PMIC Power Management Integrated
pMOS P-channel metal-oxide semiconductor
PMS Power management system
PMSM Permanent Magnet Synchronous Motor
PNL Panel
POL Polyethylene, Point-of-load
POR Power-on reset
Pot Potentiometer
POV Peak Operating Voltage
PPM Pulse Position Modulation, Parts Per Million
PRC Parasitic resistance cancellation
PRV Peak Reverse Voltage
PSI Pounds per Square Inch
PSK Phase Shift Keying
PSR Power-supply rejection
PSRR Power Supply Rejection Ratio
PT Potential Transformer
PTB Physilalish Technische Bundesanstalt
PTC Positive Temperature Coefficient
PTP Polyethylene terephthalate
PTFE Poly tetra fluoro ethylene
Pu, p.u. Per unit
PUT Programmable Unijunction Transistor
PV PhotoVoltaic
PVC Polyvinyl chloride
PVDF Polyvinylidene fluoride
PWD Pulse-width distortion
PWM Pulse width modulation
PWR Power

R or rElectrical resistance
Rad, rad Angular displacement in radians
RADAR Radio Detection and Ranging
RAM Random access memory
RCBO Residual Current Circuit Breaker with Overload Protection
RCCB means Residual Current Circuit Breaker
RCD Residual current device
RCU Remote control unit
RDOL Reverse Duty On Line Starter
Ref. Reference
rem or (R) Remote operation
REQ Required
RF Radio Frequency, describing the rate of oscillation
RFDS Radio frequency design system
RFID Radio Frequency Identification
RGB Red Green Blue
RGS Rigid Galvanized Steel Conduit
RHS Right-hand side
RIO Remote Input Output
RISC Reduced Instruction Set Computer
RJ45 Registered Jack 45. An 8 pin Ethernet Jack
RLA Rated Load Amperes
RLC Resistance Inductance Capacitance
RMC Rigid Metal Conduit
RMG Ring Main Gear
RMS, rms Root mean square
RMU Ring main unit
RNC Rigid Non-Metallic Conduit
ROM Read only memory
RPR Reverse Power Relay
RPS Revolutions per Second
RPM Revolutions per Minute
RSC Rigid Steel Conduit
RTC Real-time clock
RTD Resistance temperature detector
RTOS Real Time Operating System
RTS Remote Test Station
RTU Remote transmitter unit, Roof Top Unit
Rx Receiver
RYB Red, Yellow, Blue (Old Color Codes used for three phase Wiring – UK)

S Apparent power in volt-amperes
s or p Laplace operator in mathematics, for transfer functions
S Slip of a rotating machine with respect to 1.0 pu
SAW Surface Acoustic Wave
SB Switch Board
SBM Single buoy mooring
SC, S/C Short circuit
SCADA Supervisory control and data acquisition system
SCF Standard cubic feet of a gas
SCIM Squirrel Cage Induction Motor
SCK Serial Clock
SCR Silicon Controlled Rectifier
SCS Silicon Controller Switch
SCSI Small Computer System Interface
SDR Single discipline review
SEB Service End Line Box or Service Electrical Box
SECT Skin effect current trace heating
SELV Safety extra-low voltage
SFU Switch Fuse Unit
SF6 Sulphur hexafluoride
SI System International of Unit’s
SIM Subscriber identity module
SIO Serial Input and (serial) Output
SIPO Serial In Parallel Out
SLDB Secondary Lighting Distribution Board
SLI Double-ended, linear arc tube
SMD Surface Mount Device
SMPS Switch-mode power supply
SMSB Sub Main Switchboard
SMT Surface mount technologies
SNR Signal-to-Noise Ratio
SoC System on a Chip
SOIC Small Outline Integrated Circuit
SOLAS Safety of life at sea, a document relating to marine practice
SON Diffused ellipsoidal outer bulb, single-ended lamp
SONAR SOund NAvigation and Ranging
SON-T Clear tubular outer bulb, single-ended lamp
SON-TD, – L Clear tubular outer bulb, double-ended lamp
SON-R SON lamp, with internal reflector
SOL CU Solid copper
SOP Small Outline Package
SOT Small outline transistor
SOX U-shaped arc tube, single-ended lamp
Sox Sulphur based gas emissions
SP Single phase
SPDT Single Pole Double Throw
SPI Serial Peripheral Interface
SPICE Simulation Program with Integrated Circuit Emphasis
SPMSM Surface Permanent magnet Synchronous Motor
SPST Single Pole Single Throw
SPT Stranded Parallel Thermoplastic
sq Square, e.g. sq mm is square millimeters
SR Shift Register, Slew Rate
SRAM Static Random Access Memory
SRF Self-resonant frequency
SRIM Slip Ring Induction Motor
SRM Switched Reluctance Motor
SSB Single SideBand
SSI Small Scale Integration
SSR Solid State Relay, Synchronization check protection relay
ST Super Tension, Shunt Trip
STA Steel Tape Armoure
STG Steam turbine generator
STP Shielded Twisted Pair
STR Statimax Trip Release
STR CU Stranded copper
SW Switch, Shortwave, as in the case with shortwave bands
SWA Steel wire armour
SWBD Switchboard
SWG Standard Wire Gauge
SWGR Switchgear
SYNC, Sync Synchronizing
SYM Symmetrical
SyRM Synchronous Reluctance Motor

T or t Time, usually in seconds
TB Terminal Block
Td Time constant in seconds for the quantity ‘d’
TC Temperature Coefficient
TCP/IP Transmission Control Protocol/Internet Protocol
TDRM Time delayed restart relay
TEFC Totally enclosed fan cooled
TEL Telephone
TEM Transverse Electromagnetic (wave)
temp. Temperature
TESFC Totally enclosed separate fan cooled, fan attached to an auxiliary motor Shaft
TF Transfer Function
T/F Transformer
TFD Thin Film Detector
TFT Thin Film Transistor
TG Turbo-generator, gas or steam
TGB Telecommunications Grounding Bus bar
THD Total Harmonic Distortion
THF Telephone harmonic factor
TOP Gas-turbine operating temperature (hot-end blade temperature)
TM Technical measurement system of units
TMCB Thermal Magnetic Circuit Breaker
TCP Gas-turbine control panel
TLX Cold starting tubular fluorescent lamp, with single-pin caps
TPDT Triple Pole Double Throw
TPIC Triple Pole Iron Clad
TPN Three-phase and neutral power supply
TPPL Total plant peak load
TPRL Total plant running load
TPS Triple Pole Switch
TPST Triple Pole Single Throw
Tran., Tx Transformer
TRS Tough Rubber Sheathed
TTL Transistor-Transistor Logic
TVS-Diode Transient Voltage Suppression Diode
Tx Transmitter

U Voltage, also used for energy
UART Universal Asynchronous Receiver and Transmitter
UC, U/C Undercurrent
UCP Unit control panel
UDS Uniform Drawing System
UEL Upper explosive limit
UF, U/F Under frequency
UG Under Ground
UHF Ultra high frequency
UI, U/I Undercurrent
UJT Unijunction Transistor
UL, U/L Under load
UL Underwriters Laboratory (USA)
UVLO Under voltage lockout
UNO Unless noted otherwise
UPS Uninterruptible power supply unit
USART Universal Synchronous and Asynchronous Receiver and Transmitter
USB Universal Serial Bus
UTP Unshielded Twisted Pair
UV, U/V Under voltage

V, U Voltage or volts
VA Volt-amperes
VAC, Vac Alternating voltage
VAr, Var Reactive volt-amperes
VCA Voltage Controlled Amplifier
VCB Vacuum Circuit Breaker
VCC Voltage at the common collector
VCCS Voltage Controlled Current Source
VCD Variable Capacitance Diode
VCO Voltage Controlled Oscillator
VCXO Voltage-Controlled Crystal Oscillator
VDC, Vdc Direct voltage
VDE Verband Deutscher Electrechniker (Germany).
VDI Verein Deutscher Ingenieure (Germany).
VDU Visual display unit
VFD Variable Frequency Drive, Vacuum Fluorescent Display
VFDP Variable Frequency Drive Panel
VFO Variable-frequency oscillator
VGA Video Graphics Adapter
VHF Very high frequency
VIR Vulcanized Indian Rubber
VLSI Very Large Scale Integration
VOM Volt Ohm Meter, a device also known as a millimeter or multitester
VSD, VSDS Variable speed drive systems
VSI Voltage source inverter
VSWR Voltage Standing Wave Ratio
V.T., VT Voltage transformer
v/v Comparison by volume, per-unit
VVVF Variable Voltage Variable Frequency Drive

W or P Active power, watts
w orωFrequency in radians per second.
wdg. Winding of a machine or transformer
WH Water Heater
WHRU Waste heat recovery unit
WLAN Wireless Local Area Network
WP Weather Proof
WRIM Wound Rotor Induction Motor
WRSM Wound Rotor Synchronous Motor
WSN Wireless Sensor Network

Z Electrical impedance
ZH Zero halogen, as used for cables
ZVC Zero voltage crossing
ZVS Zero voltage switching

Numerical

1P, SP Single phase
3P Three-phase supply
3P-N Three-phase and neutral supply
3P-N-E Three-phase neutral and earth supply
2W Two-wire supply
3W Three-wire supply
4W Four-wire supply
3G Third Generation
3R3 3.3 ohm Resistor
4K 4,000 pixels
4P4T Quad-Pole Quad-Throw
4WJ Four-Way Junction

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