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[5 minutes] Let you know what is circuit breaker for electrical equipment!

Datetime: 11/4/2022 2:41:00 PM   Visit: 69

On "Why do circuit breakers close", "Solutions for circuit breakers failure", "What is spring stored energy in circuit breakers", "Can circuit breakers become weak", "Where are circuit breakers used", "What is the difference between isolator and circuit breaker?” I believe many friends are interested in learning about them, because these topics are also very hot, so since everyone wants to know now, let’s share them with you.

Why does the circuit breaker close?
The reasons for a circuit breaker to the trip are:
1. Overload protection: The current setting value of the circuit breaker is too low, and the power of the load is greater than the rated power of the circuit breaker.
2. Circuit short circuit protection: Check whether the power plug is dry.
3. Leakage protection: The aging and leakage of the line will cause both the live line and the neutral line to be energized.
4. Under-voltage protection: the voltage is unstable, and it will automatically trip when the voltage drops to the set value.

Solutions to a faulty circuit breaker:


Fault phenomenon




Manually operated circuit breaker does not close

1. The undervoltage release has no voltage or the coil is damaged

2. The energy storage spring is deformed, resulting in a decrease in the closing force

3. The reaction spring force is too large

4. The mechanism cannot be reset and then buckled

1. Check the circuit, apply voltage or replace the coil

2. Replace the energy storage spring

3. Readjust the spring reaction force

4. Adjust the re-buckling contact surface to the specified value


Electrically operated circuit breaker does not close

1. The source voltage does not meet the

2. Insufficient power supply capacity

3. The stroke of the electromagnetic pull rod is not enough

4. Motor operation positioning switch displacement

5. The rectifier tube or capacitor in the controller is damaged

1. Replace the power supply

2. Increase the operating power capacity

3. Readjust

4. Readjust

5. Replace damaged components


A phase contact cannot be closed

1. One-phase connecting rod of the general circuit breaker is broken
2. The repulsive opening mechanism of the current limiting circuit breaker can be folded and the angle of the connecting rod can be enlarged.

1. Replace the connecting rod
2. Adjusted to the specified value of the meta-technical conditions


The shunt release cannot make the circuit breaker open 1. Coil short circuit
2. The power supply voltage is too low
3. The contact surface of the re-buckling is too large
4. Loose screws
1. Replace the coil
2. Replace the power supply voltage
3. Readjust
4. Tighten


The undervoltage release cannot open the circuit breaker 1. The reaction spring becomes smaller
2. If the shortlisted energy storage is released, the energy storage spring will be deformed or broken
3. The organization is stuck
1. Adjust the spring
2. Adjust or replace the energy storage spring
3. Eliminate the cause of structural stuck, such as rust, etc.


The circuit breaker opens immediately when the motor is started

1. The instantaneous setting value of overcurrent tripping is too small
2. Some parts of the release are damaged, such as semiconductor rubber film, etc.
3. The reaction force spring of the release is broken or dropped

1. Readjust
2. Replace


After the circuit breaker is closed, it will automatically break after a certain period of time 1. The long-time delay setting value of the overcurrent release is incorrect
2. Changes in parameters of thermal elements or semiconductor delay circuit elements
1. Adjust the contact pressure or replace the spring
2. Replace the contact or clean the contact surface, it can't be better, only the whole circuit breaker can be replaced
3. Tighten
4. Remove oil or oxide layer


Circuit breaker temperature rises too high 1. The contact pressure is too low
2. Excessive wear or poor contact on the contact surface
3. The connecting screws of the two conductive parts are loose
4. Oxidation of oil stains on the tap surface
1. Correct or reinstall the contact bridge
2. Replace the rotating lever or replace the help switch
3. Adjust the contacts and clean the oxide film


Undervoltage release noise 1. The reaction spring is too large
2. There is oil on the working surface of the iron core
3. The short-circuit ring is broken
1. Readjust
2. Remove oil stains
3. Replace the bit or core


The switch does not work 1. The switch is stuck or disconnected
2. The switch transmission rod is broken or the roller falls off
3. The contacts do not touch or oxidize
1. Correct or reinstall the touch bridge
2. Replace the lever or replace the help switch
3. Adjust the contacts and clean the oxide film


Malfunction of circuit breaker with semiconductor release 1. Damaged semiconductor release components
2. External electromagnetic interference
1. Replace damaged components
2. Eliminate external interference, such as the operation of the large electromagnet near, the contactor disconnection, electric welding, etc., isolate or replace


Leakage circuit breakers often break by themselves 1. Leakage action current change
2. The line has leakage
1. Send it to the manufacturer for recalibration
2. Find out the reason and solve it


The earth leakage circuit breaker cannot be closed 1. The operating mechanism is damaged
2. There is leakage or grounding somewhere in the line
1. Send to the factory for processing
2. Clear leakage or ground fault

What is the spring stored energy of a circuit breaker?
The energy storage of the circuit breaker mainly refers to stretching the closing or opening spring to make it have corresponding potential energy. Like triggering a gun. The energy storage spring is connected to the closing or opening mechanism. When closing or opening, the closing or opening electromagnet acts, and after pulling the "trigger", the closing or opening spring quickly closes or separates the moving contacts of the circuit breaker, and its main purpose is to reduce The arc existence time of closing or opening achieves the purpose of rapid arc extinguishing. The energy storage of some circuit breakers can be carried out manually or electrically.

Will the circuit breaker get weaker?
With the increase in running time, the tightening, friction, lubrication, and tolerance of the operating mechanism of the circuit breaker will change, which will affect the closing time, operating voltage, and other characteristics. At the same time, with the accumulation of the number of times the fault current is removed, the contacts will also wear to a certain extent.

Where are circuit breakers used?
Circuit breakers are divided into high-voltage circuit breakers and low-voltage circuit breakers according to their scope of use. High-voltage circuit breakers are the main power control equipment in power plants and substations. They have arc-extinguishing characteristics. When the system is running normally, it can cut off and connect lines and the no-load and load currents of various electrical equipment; when the system fails It cooperates with the relay protection to quickly cut off the fault current to prevent the expansion of the scope of the accident.

What is the difference between an isolator and a circuit breaker?
What is the difference between a circuit breaker and a disconnect switch? The main difference between the two lies in the way of operation and the effect is not the same. The former is mainly able to isolate the circuit, and it has an arc suppression device that can cut off the current. And generally speaking, it can start when the current is overloaded, or when a fault occurs, it can automatically trip, and it is a long-distance power control.

The latter has the function of the isolator, which can play the role of disconnection and protect the safety of workers. One difference is that it does not have arc suppression equipment, and can only cut off the no-load current, which is basically manual operation before it can run normally.

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