8 notices about high and low voltage switchgear
Nov 28, 2020
Isolation switches, AC contactors, small relays, thermal relays, buttons, indicator lights, all-round switches and limit switches are the eight most common components in the control loop of electrical control systems
1. Isolating switch
Low-voltage circuit breakers are also called fully automatic air leakage switches. They can be used as manual power switches. They can also be used to distribute electromagnetic energy, start three-phase asynchronous motors infrequently, and implement maintenance on power plugs, motors, etc., when they generate serious loads. , Short-circuit fault or undervoltage protection and other common faults, the power supply circuit should be automatically disconnected.
The letter symbol of the isolating switch is: QF
2. AC contactor
AC contactor is composed of electromagnetic induction organization and circuit breaker system software. The most common electromagnetic coil operating voltage of AC contactor is AC380V, AC380V and DC380V.
The electromagnetic induction organization of AC contactor is composed of electromagnetic coil and moving iron core (current coil) Kuche iron core; AC contactor circuit breaker system software is composed of two parts: main circuit breaker and auxiliary circuit breaker. The main circuit breaker is used to conduct the main power supply. Circuit, auxiliary circuit breaker is used to control the loop.
The letter symbol of AC contactor is: KM
3. Thermal relay
The thermal relay is an automotive relay that uses the amount of current to reverse the posture based on the basic principle of the thermoelectric effect caused by the components.
Thermal relay letter symbol: FR
4. Small relay
The basic principle of the small relay is to change a key-in data signal into several output data signals or to make the data signal larger (that is, to expand the volume of the car relay circuit breaker). Its essence is a voltage relay, but it has many circuit breakers (up to 8 pairs), the circuit breaker volume reaches 5-10A, and the posture is smart.
When most of the circuit breakers of other household appliances are insufficient, small relays can be used to expand the majority of their circuit breakers, and the expansion of the power supply volume for electric shock accidents can also be completed based on the small relays.
Small relay letter symbol: KA
5. Button
In specific applications, the buttons are generally selected according to the total number of circuit breakers required, the place of application and the color tone. Common product buttons such as LA18, LA19, LA20 are suitable for AC500V, DC440V, rated voltage 5A, and the control output power is in the control circuit of AC300W, DC70W.
Key letter symbol: SB
Key tone regulations:
(1) The "stop" button and the "change direction" button must be bright red. When pressing the red button, be sure to stop the machine equipment or turn off the power.
(2) The hue of the "Start" button is emerald green.
(3) The buttons for the alternate postures of "Start" and "Stop" must be gray-black, milky white or dark gray. Red and green buttons cannot be used.
(4) The button for "start light" must be gray and black.
(5) "Calibration" (if there is a calibration button to maintain the car relay) must be dark blue, and when the calibration button also has a termination function, it must be bright red.
6. Indicator light
The function of the indicator light:
(1) Indicate the operation or termination of machinery and equipment.
(2) Monitor whether the switching power supply of household appliances is normal.
(3) Use the green light to monitor whether everything is normal in the power trip control loop, and use the signal light to monitor whether everything is normal in the reclosing control loop.
7. Toggle switch
The all-round conversion power switch is composed of components such as actual operation organization, control panel, rocker and multiple circuit breaker seats.
Almighty switch letter symbol is: SA
The conduction status of each circuit breaker when the rocker is turned to different gears is indicated by a small black dot, a small black dot indicates that the circuit breaker is closed, and a small black dot indicates that the circuit breaker is off.
8. Limit switch
The letter symbol of the limit switch is: SQ
