The common plastic case circuit breakers are mainly frame circuit breakers and air circuit breakers. The structure of the frame circuit breakers has different components according to the different functions of the products. For example, the following plastic case circuit breakers have different components.

Composition of Frame Circuit Breaker

Air circuit breaker

Composition of ABB-F Frame Circuit Breaker

Function introduction of important components of plastic case circuit breaker:

1. The main components of a fixed frame circuit breaker are: circuit breaker body, tripping unit and accessories.

2. The main components of an extractive frame circuit breaker are: circuit breaker body, moving part, fixed part, release unit and accessories.

3. Main components: split/close coil, energy storage motor, under-voltage tripper and protection unit.

Introduction of Component Functions:

1. Open/close coil:

Also known as switch-on electromagnet, as the switch-on control component of circuit breaker, is the driving mechanism of switchgear operation, which is controlled by the controller of switchgear and driven by instantaneous power supply. YC type is closing coil, Y0 type is opening coil.

2. Energy storage motor:

It is used for high and low voltage circuit breaker of spring energy storage type to provide energy for switch mechanism opening and closing. When the switch is switched off, the spring releases energy, the energy storage motor starts to work, and the motor stops when the spring stretches and stores energy in place.

3. Undervoltage tripper:

When the terminal voltage of the circuit breaker drops to a specified range and the circuit breaker has delayed or no delayed disconnection, the undervoltage tripper shall operate when the power supply voltage drops (or even slowly drops) to 70% to 35% of the rated working voltage. When the power supply voltage equals 35% of the rated working voltage of the circuit breaker, the undervoltage tripper shall be able to prevent the circuit breaker from closing. When the power supply voltage is equal to or greater than the rated working voltage of 85% undervoltage tripper, the reliable closure of circuit breaker should be guaranteed under the hot condition.

4. Electronic release:

It is a circuit consisting of electronic components, which detects the current of main circuit, amplifies and promotes the tripping mechanism, which is mechanically connected with the circuit breaker (or constitutes a whole) to release the holding mechanism and automatically disconnect the circuit breaker, and to protect the power supply circuit and load.

Introduction of common protective functional components:

1. L-overload long delay is mainly overload protection, the action time is longer, generally fixed time limit (time division, time level);

2. S-short-circuit short delay 1. Generally short delay uses inverse time limit (multiple of 0.1s, not exceeding Is);

3. I-Short Circuit Instantaneous - Instantaneous Protection does not need delay, as long as it reaches the instantaneous value, it will trip immediately (several ms);

4. G-Ground Fault Protection - When an electrical fault occurs between one or more phase conductors and the ground, the grounding fault protection warns by jumping off the circuit breaker or alarming (including leakage protection, tens of ms).

5. Instantaneous short circuit protection:

Aiming at the short-circuit situation of the circuit, when the short-circuit fault occurs, the short-circuit current of the circuit is very large, which requires or protects components to quickly disconnect the circuit to protect other equipment in the circuit from being damaged by the short-circuit current. The action current value of instantaneous protection is relatively large, and the action time is very fast.

6. Delayed circuit breaking protection:

Usually installed in the power supply circuit to some power supply circuit. When a short circuit occurs in the next circuit, there should be a short circuit protection action in the next circuit. Therefore, the short circuit current can be avoided by delaying, and the power supply can be continued without disconnecting the lower circuit, instead of all circuits being disconnected because of a circuit fault.

Delayed short-circuit protection generally has the function of reverse idle time. When the short-circuit current is small, it shows that the fault is at the far end, it will delay. When the short circuit current is very large, it means that the fault occurs in the power supply circuit and can be instantaneously disconnected.

Short-circuit delay and short-time instantaneous should be matched to avoid the blind area of protection.

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