Identification of letter symbols on the PCB board

I often hear people ask what the letters on the PCB board mean?what is its function, everything in the world has its role and meaning, even if it is an object, just like the symbol on the PCB board also has its unique role, let’s learn about the meaning of the letters on the circuit board!

The letters in the numbers printed on the PCB light board are mainly for SMT patches and quality problems after being made into finished products, you can quickly find the cause and repair them in time.

The letters on the PCB board represent respectively:

Rx is a resistor, there are many resistors in the circuit diagram, according to the serial number, R1, R2, R3…

Cx is the non-polar capacitor, the anti-interference capacitor at the input of the power supply,  the C chip (integrated circuit module), the Ux is the IC (integrated circuit component), the Tx is the test point (for factory testing), and the Spk1 is the speaker (buzzer, horn);

Qx is a transistor, Jx is a jack (such as Audio jack), R (resistor), FS (fuse); L: Inductance, FB: fuse, P: sometimes indicates port (socket, etc.)  RTH (thermistor), CY (Y capacitance: high-voltage ceramic capacitor, safety), CX (X capacitance: high-voltage film capacitor, safety), D: diode or regulator, X and Y represent: crystal oscillator, C (capacitor), Q transistor (transistor), ZD regulator diode, T transformer, U integrated chip (IC chip), J (jumper), VR (adjustable resistance), W regulator, K switch, Y crystal oscillator;

AAT: Power Automatic Input Device, AC: Alternating Current, DC: Current, FU: Fuse, G: Generator, M: Motor, HG: Green Light, HR: Red Light, HW: White Light, HP: Light Plate, K: Relay, KA (NZ): Current Relay (Negative Sequence Zero Sequence), KD: Differential Relay, KF: Flash Relay, KH: Thermal Relay, KM: Intermediate Relay, KOF: Outlet Intermediate Relay, KS: Signal Relay, KT: Time Relay, KV (NZ) : Voltage Relay (Negative Sequence Zero Sequence), KP: Polarization Relay, KR Reed Relay, KI Impedance Relay, KW (NZ) Power Direction Relay (Negative Sequence Zero Sequence), KM Contactor, KA Transient Relay; Instantaneous with or without relays, AC relays, KV voltage relays,

L lines, QF circuit breakers, QS disconnectors, T transformers, TA current transformers, TV voltage transformers, W DC bus, YC closing coils, YT trip coils, PQS active and reactive power, EUI electromotive force voltage current, SE experimental button, SR reset button, F frequency, Q circuit switching device, FU fuse, FR thermal relay, KM contactor, KA1, instantaneous contact relay 2, instantaneous With or without relay 3. AC relay, KT delay with or without relay, SB button switch, SA transfer switch;

U:Rectifier, SR Reset Button, SBT Test Button, SBE Emergency Button, SBS Stop Button, SBR Reverse Button, SBF Forward Button, SA Ammeter Transfer Switch, SV Voltmeter Transfer Switch, ST Temperature Control Switch Auxiliary Switch, SS Speed Control Switch,  SP Pressure Control Switch,SM Humidity Control Switch, SL Level Control Switch, SK Time Control Switch, SH Manual Control Switch, SQP Proximity Switch, SQ Limit Switch, CE Power Capacitor, C Capacitor, FV Voltage Limiting Protection Device, FF Cutout Fuse, FTF Fast Fuse, FU Fuse, F Arrester, WELM Accident Lighting Bus, WV Voltage Bus, WPS Forecast Audio Bus, WFS Accident Audio Bus, WF Flash Bus, WS Signal Bus, WC Control Bus, WCL Closing Bus, WT Conductor Line, WEM Emergency Lighting Trunk, WLM Lighting Trunk, WPM Power Trunk, WE Emergency Lighting Branch Cable, WL Lighting Branch, WP Power Branch, WIB Plug-in (Feed) Bus, WB DC Bus, W Wire and Cable Bus, XT Terminal Board, XS Socket, XP Plug, XB Connecting Piece, HW White Light, Blue Light, HY Yellow Light, HG Green Light, HR Red Light, HLHS Indicator Light, HA Light Signal, PAR Acoustic Signal, PR Reactive Energy Meter PA: Ammeter, PV: Voltmeter, PJ: Active Energy Meter, PJR: Reactive Energy Meter, PF: Frequency Meter, PPA: Phase Meter, Maximum Demand Meter (Load Monitor), M Power Factor Meter PPF Active Power Meter, PW Reactive Power Meter;

UR thyristor rectifier, VC control circuit rectifier with power supply, UF inverter, UC converter, UI inverter, M motor, MA asynchronous motor, MS synchronous motor, MD DC motor, MW wound rotor induction motor, MC squirrel cage motor, YM: electric valve, YV: solenoid valve, YF:  fire damper, YS: smoke exhaust valve, YL: electromagnetic lock, YT: trip coil, YC: closing coil, YPAYA: pneumatic actuator, YE: electric actuator, FH: Heating device (electric heating), EL: Lighting (light emitting device), EV: Air Regulator, EE: Electric Heater Heating Element, L: Induction coil reactor,  LF: Excitation coil,  LA: arc suppression coil, LL: filter capacitor, R: resistor rheostat, RP: potentiometer, RT: thermistor, RL photoresistor, RPS varistor, RG ground resistor, RD discharge resistor, RS starting rheostat, RF frequency sensitive rheostat, RC current limiting resistor, B photocell thermoelectric sensor, BP pressure converter, BT temperature converter, BV speed converter, BT1BK time measurement sensor, BL liquid level measurement sensor, BHB temperature measurement sensor.

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