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The working principle of the control circuit of the circuit breaker

Views: 8     Author: Site Editor     Publish Time: 2022-08-01      Origin: Site

Circuit Breaker Control Circuit

The opening and closing of the circuit breaker is performed by using the operating element to issue instructions to the operating mechanism of the circuit breaker through the control circuit.

Type Of Control Loop

1. According to the distance, it can be divided into distance control and local control.

(1) Distance control

It is to control the circuit breakers of important electrical equipment in the centralized control room through tens to hundreds of meters, such as the control of generators, transformers, 110kV and above lines, etc.

(2) Local control

In order to reduce the monitoring surface of the operators, reduce the area of the control room and save the control cables, some circuit breakers that are not important or do not need to be monitored frequently are controlled at the installation site, which is called local control, such as 10kV lines and circuit breakers. Plant load, etc.

2. According to different operation modes, it can be divided into one-to-one control and one-to-N control.

(1) One-to-one Control

An operating element (SA) controls a circuit breaker.

(2) One-to-N Control

One operating element controls multiple circuit breakers by means of line selection.

3.  According to the different power supply voltage levels, it can be divided into strong current control and weak current control.

(1) Strong Current Control

The strong current control voltage is generally DC 220V or 110V, which is a traditional control voltage.

(2) Weak Current Control

The voltage is generally DC 48V or 24V, which can be used for one-to-N control mode and is easy to interface with computer control.

Since the opening and closing of the circuit breaker requires a certain amount of power, the weak voltage cannot meet the requirements, and the opening and closing of the circuit breaker still requires a strong voltage, so the weak current control is actually connected to the strong current through the intermediate relay, there by realize the control of the circuit breaker.

4. According to different operating mechanisms, it can be divided into DC power control and AC power control.

(1) DC Power Control

The circuit breaker of the electromagnetic operating mechanism can only be controlled by DC power.

(2) AC Power Control

The circuit breakers of the spring operating mechanism and the manual operating mechanism can be used for both AC and DC, but are generally controlled by AC power.

circuit breaker

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See More:  CSQ Circuit Breaker Types

The Composition Of The Control Loop

(1) Control Element

The control element consists of a manually-operated control switch SA or an automatically-operated automatic device and the corresponding relay contacts of the relay protection device.

(2) Intermediate Link

The intermediate link refers to the control circuit composed of components such as connection control, signal, protection, automatic device, execution and power supply. Depending on the operating mechanism and the control distance, the composition of the control circuit is different.

(3) Operating Mechanism

In the operating mechanism, the closing coil (YC) and the trip coil (YT) are connected to the control circuit. When closing, due to the large current taken by YC, the electrical capacity of the control loop cannot meet the requirements, and it must be controlled by an intermediate amplifier element, that is, SA is used to control the closing contactor KM, and then the main contact of KM is used to control the electromagnetic operating mechanism the YC.

Basic Requirements for Control Loops

(1) It can manually use the control switch to open and close the circuit breaker.

(2) Meet the requirements of automatic devices and relay protection devices. When the controlled equipment is in standby, the equipment can be automatically put into operation by the automatic device through the circuit breaker. When the equipment fails, the relay protection device can automatically trip the circuit breaker to remove the fault.

(3) The operation of opening and closing can be completed in a short time. Since YC and YT are designed to pass the working current for a short time, the circuit breaker should be automatically disconnected immediately after opening and closing to avoid burning out the coil.

(4) It can prevent the jumping of the circuit breaker for many times in a short period of time.




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