Causes of leakage circuit breaker protection switch tripping

Leakage protector trip cause

The function of the leakage protector is to effectively control the disconnection of the home circuit and the occurrence of electric leakage and electrical accidents. Therefore, the reasons for tripping can be divided into two types, one is normal tripping and the other is abnormal tripping.

1, normal tripping

If the rated leakage current is 30MA, the leakage current will be more than 25MA in the load, and the leakage switch will trip. Since the current of the 25MA is safe to flow through the human body, there is no electric shock to death; the same is true for the line or electrical equipment, and the operation of the electrical equipment does not cause an abnormal phenomenon.

2, abnormal trip

This kind of trip is caused by the unqualified quality of the leakage switch itself, which can be divided into two categories and sometimes no reason to trip. In the case that the leakage switch is connected to the power supply without being connected to the load, if it is not connected, it is definitely the quality problem of the leakage switch. Do not repair it yourself, because it must be tested after technical performance before being put into use. No test equipment is used. It is not safe to use after testing.

The second type is occasional tripping, especially when it is tripped in the middle of the night or when there is no one in the home. This trip indicates that the leakage resistance of the leakage switch is poor. The leakage switch with abnormal trip should be removed and replaced with a good leakage switch.

If the leakage current of the normal tripping fluctuates around 25MA, the phenomenon is similar to the occasional trip. The cause of the leakage of the leakage protector is often caused by the insulation aging of the wire, that is, when the environment is wet, it trips, and when the environment is dry, it does not trip. A reliable way to distinguish between such normal trips and occasional trips is to measure the insulation resistance of lines and electrical equipment. The standard stipulates that the insulation resistance of each wire shall not be less than 0.5MΩ, and the insulation resistance of electrical equipment is usually greater than 0.5MΩ. If the load connected to the leakage switch is less than 8.8KΩ (220V/25MA=8.8KΩ), a normal trip will occur.

(1) Poor installation. The lead wires of each pile head are not firmly connected, and the looseness of the pile head will cause heat and oxidation of the pile hair, burn out the outer insulation of the wire, and emit sparks and burnt smell, causing the line to be under pressure and the air switch to operate.

(2) There is a problem with the quality of the leakage switch itself.

(3) Does not match the load. The actual electrical load of the home is greater than the rated current of the low voltage circuit breaker on the line. It usually occurs after new installation or new use of high-power household appliances such as air conditioners and electric water heaters. The matching air switch must be replaced.

(4) Electrical or line leakage or short circuit. When it is found that the electrical appliance used is leaking, just unplug the electrical faulty electrical appliance and reconnect the low voltage circuit breaker to send power.

After the low-voltage circuit breaker trips, first disconnect all the shunts, and then turn them on one by one. When a certain road is closed, the low-voltage circuit breaker can not be powered on, that is, the branch is faulty. The road should be disconnected and the other branches should be connected to transmit power. After detecting the problem of the fault shunt, it is repaired and then sent.

(5) The power supply line voltage is too high. This is very dangerous and generally occurs in “three-phase four-wire” power supply residential buildings. At this time, look at whether the line is powered by two lines; second, see if the neighbors are also tripping; three use a multimeter to measure the incoming line voltage. Never put a low-voltage circuit breaker on hold, otherwise it will burn the appliance and cause a fire.

Check the cause of the leakage protector trip

1, the line elimination method

According to the order of “first trunk, re-branch, and rear end”, each branch line of the low-voltage power grid is disconnected, and only the main line is tested and sent. If the trunk line has no fault, the trunk line can operate normally. Then, the branches and ends are put into operation in turn. When the line is put into operation, the protector trips, and on which line the fault point is located, the fault point can be found centrally on this line.

2, intuitive inspection method

Visually inspect the protected area including the residual current action protector and the protected line device to find the point of failure. During the inspection, attention should be paid to checking the complex sections and fault-prone points of the corners, branches, cross-overs of the line.

3. Numerical comparison method

The instrument or meter is used to measure the line or equipment, and the measured value is compared with the original value to find the fault point.

Note: When the line neutral line insulation drops or the device neutral line is repeatedly grounded, it is easy to cause the total protection to trip frequently, and the secondary protector does not trip.

4, test delivery method

It mainly searches for the residual current action protector itself. The specific operation method is: first cut off the power supply, and then remove the zero-sequence transformer load side lead of the residual current action protector and remove the protector.

If the protector still fails to operate, the protector itself is faulty and should be repaired or replaced. If it can operate normally, the protector itself is not faulty, and then find the switchboard or line. The operation method is as follows: firstly cut off the output of each line or AC contactor. If it cannot be operated, it indicates that there is a fault on the switchboard. It should be checked whether the electrical and instrumentation equipment of each road is well insulated and the wiring is correct; if it can operate normally, it means There is no fault on the switchboard. When it is confirmed that the fault occurs on the external line, the branch line elimination method can be used to find the fault point.