Plastic case circuit breaker always has some faults in use. Here are some common faults to illustrate:

1. Frequent trips occur

1. Overload tripping of circuit breaker caused by unbalanced three-phase load; finding out load condition and setting current reasonably

2. Choosing the connected cable or copper plate section area is too small to cause fever and circuit breaker tripping; ascertaining the size and length of the cable section; choosing the section area length of the cable or copper bar correctly and reasonably according to the sample.

3. Connecting screw does not tighten or poor contact causes contact resistance to rise, which is caused by a large number of heating at the connection or even burning circuit breakers, resulting in switch tripping; find out the connection situation, tighten the screw.

4. If the distance between the distribution cabinet and the electrical equipment is too far, the voltage drop of the line will increase, which will cause the segment voltage of the motor on the load side to be lower than the rated voltage, then the starting current will increase and the circuit breaker will trip. Find out what the terminal voltage of the motor side is. Reasonable determination of rated current and instantaneous protection action current of switch

2. Short-circuit skip tripping

Generally, the protection characteristics of each series circuit breaker are mismatched and selected, and there is no appropriate safety time.

Improper choices may have the following types of problems:

1. Plastic case circuit breaker does not trip, universal circuit breaker trips.

2. Low Voltage Circuit Breakers (Containing Plastic Shell Circuit Breakers and Universal Circuit Breakers) Do not Trip, High Voltage Side Protectors Trip

In the analysis, we should understand the line problems, including the length and section of the connecting cable, the estimation of short-circuit current, the estimation of the current of the circuit breaker, the occurrence time of short-circuit fault and so on. Often, due to improper matching and selection, there are more over-step trips. In order to prove this problem, the state of circuit breaker can be checked on site at last. If there is no segregation, the product should be judged as normal. Generally, the possibility of failure of the product itself is very small, and the quality problem should not be admitted before the problem has been clarified.

3. Trip as soon as it is put into operation

1. Three-phase power supply lines, including zero lines, do not pass through the zero-sequence current transformer in the same direction, and correct wiring can be done.

2. Installation of leakage circuit breaker and non-installation of leakage circuit breaker are connected electrically, the two kinds of circuits can be separated.

3. There is a fire-to-ground load in the line, so it can be eliminated.

4. Repeated grounding should be eliminated in the zero-line running through the zero-sequence current transformer.

5. Leakage circuit breakers should be replaced because of their own faults.

4. Misaction

1. Over-voltage: When operating overvoltage occurs in the line, the circuit breaker can be used to act. At this time, delay or impulse voltage inactive leakage circuit breaker can be selected. Resistance-capacitance absorption circuit can be installed between contacts to suppress overvoltage, and over-voltage absorption device can also be put into the circuit.

2. Electromagnetic interference: If there are magnetic devices or high-power electrical devices nearby, the installation position of leakage circuit breaker should be adjusted to stay away from such electrical components.

3. Circumfluence effect: If two transformers operate in parallel, each transformer has its own grounding, because the impedance of the two transformers can not be completely equal, this will generate circulation in the grounding line, cause circuit breaker action, and remove one grounding line. In addition, the same transformer supplies power to the same load through two parallel loops, and the current in the two loops can not be exactly the same. Circulation may also occur, so the two loops should be operated separately.

4. The insulation resistance of working zero wire is reduced. When the insulation resistance of the working zero line is reduced, if the three-phase load is unbalanced, a relatively large working current will appear on the zero line and flow to other branches through the ground, thus leakage current will appear on each leakage circuit breaker, which will cause the wrong operation of the circuit breaker.

5. Improper grounding: If the zero line is repeatedly grounded, it will cause the malfunction of leakage circuit breaker.

6. The effect of overload, overload and short-circuit: If the leakage circuit breaker colleagues have short-circuit protection and overcurrent protection, when the setting current of overcurrent protection tripper is not appropriate, the wrong action will occur, then the setting current value can be adjusted.

Summary: All kinds of circuit breaker accessory faults will be directly replaced after wiring, installation, or use errors are eliminated.