Comprehensive List of Circuit Symbol Letters

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Comprehensive List of Symbolic Notations for Circuit Diagrams: AAT – Automatic Power Supply Switching Device; AC – Alternating Current; DC – Direct Current; FU – Fuse; G – Generator; M – Motor; HG – Green Light; HR – Red Light; HW – White Light; HP – Optical Sign; K – Relay; KA(NZ) – Current Relay (Negative/Zero Sequence); KD – Differential Relay; KF – Flashing Relay; KH – Thermal Relay; KM – Intermediate Relay; KOF – Output Intermediate Relay; KS – Signal Relay; KT – Time Relay; KV(NZ) – Voltage Relay (Negative/Zero Sequence); KP – Polarization Relay; KR – Reed Relay; KI – Impedance Relay; KW(NZ) – Power Direction Relay (Negative/Zero Sequence); KM – Contactor; KA – Instantaneous Relay ； Instantaneous with or without relay ； AC relay, KV voltage relay, L circuit, QF circuit breaker, QS isolating switch, T transformer, TA current transformer, TV voltage transformer, W DC busbar, YC closing coil, YT tripping coil, PQS active power, reactive power, apparent power, EUI electromotive force, voltage, current, SE test button, SR reset button, f frequency. Q – Switching device of the circuit; FU – Fuse; FR – Thermal relay; KM – Contactor; KA – 1. Instantaneous contact relay, 2. Instantaneous on/off relay, 3. AC relay; KT – Delayed on/off relay; SB – Push-button switch; Q – Switching device of the circuit; FU – Fuse; KM – Contactor; KA – 1. Instantaneous contact relay, 2. Instantaneous on/off relay, 3. AC relay; KT – Delayed on/off relay; SB – Push-button switch; SA – Changeover switch, ammeter PA, voltmeter PV, active energy meter PJ, reactive energy meter PJR, frequency meter PF, phase meter PPA, maximum demand meter (load monitor), PM power factor meter, PPF active power meter, PW reactive power meter, PR reactive current meter, PAR sound signal, HA optical signal, HS indicator light, HL red light, HR green light, HG yellow light, HY blue light, HB white light, HW connecting piece, XB plug, XP socket, XS terminal block, XT wire and cable busbar, W DC busbar, WB plug-in (feeding) busbar, WIB power branch line, WP lighting branch line, WL emergency lighting branch line, WE main power line, WPM lighting main line, WLM emergency lighting main line, WEM sliding contact wire, WT closing sub-busbar, WCL control sub-busbar, WC signal sub-busbar, WS flashing sub-busbar, WF alarm sound sub-busbar, WFS pre-alarm sound sub-busbar, WPS voltage sub-busbar, WV emergency lighting sub-busbar, WELM arrester, F fuse, FU fast fuse, FTF drop-out fuse, FF voltage limiting protection device, FV capacitor, C power capacitor, CE forward button, SBF reverse button, SBR stop button, SBS emergency button, SBE test button, SBT reset button, SR limit switch, SQ proximity switch, SQP manual control switch, SH time control switch, SK level control switch, SL humidity control switch, SM pressure control switch, SP speed control switch, SS temperature control switch, auxiliary switch ST, voltmeter switching switch, SV ammeter switching switch, SA rectifier, U thyristor rectifier, UR rectifier with power supply in control circuit, VC frequency converter, UF converter, UC inverter, UI motor, M asynchronous motor, MA synchronous motor, MS DC motor, MD wound-rotor induction motor, MW squirrel-cage motor, MC electric valve, YM solenoid valve, YV fire valve, YS electromagnetic lock, YL tripping coil, YT closing coil, YC pneumatic actuator, YPAYA electric actuator, YE heating element (electric heating), FH light (light-emitting element), EL air conditioner, EV electric heater heating element, EE induction coil reactor, L excitation coil, LF arc suppression coil, LA filtering capacitor, LL resistor, variable resistor R, potentiometer RP, thermistor RT, photoresistor RL, varistor RPS, grounding resistance RG, discharge resistor RD, starting resistor RS, frequency-sensitive resistor RF, current limiting resistor RC, photocell, thermoelectric sensor B, pressure transducer BP, temperature transducer BT, speed transducer BV, time measurement sensor BT1BK, level measurement sensor BL, temperature measurement sensor BHBM