Vacuum circuit breaker vacuum bubble vacuum degree reduced

The vacuum circuit breaker interrupts the current and extinguishes the arc in the vacuum bubble. Since the vacuum circuit breaker itself does not have a device for qualitatively and quantitatively monitoring the characteristics of the vacuum degree, the vacuum degree is reduced, and the fault is not easy to be found, and its danger is far greater than other dominant faults. The main reasons for the reduction of vacuum degree are: there are problems in the material or production process of the corrugated tube in the vacuum bubble, and leakage occurs after repeated operations; there are problems in the material or production process of the vacuum bubble, and there are small leakage points in the vacuum bubble itself; split type When the vacuum circuit breaker is in operation, due to the relatively large distance of the operating connecting rod, it directly affects the characteristics of the vacuum circuit breaker, such as synchronization, bounce, and overtravel, so that the speed of vacuum reduction is accelerated. The reduction of the vacuum degree will seriously affect the ability and service life of the vacuum circuit breaker to interrupt the current, and the vacuum circuit breaker will also explode when the vacuum degree is relatively low. The vacuum bubble is subjected to a qualitative test of the vacuum degree to ensure that the vacuum bubble has a certain degree of vacuum; when the vacuum degree decreases, the vacuum bubble must be replaced, and the characteristics such as stroke, synchronization, and bounce should be tested.

Vacuum circuit breaker closing failure

There are four reasons for the refusal of the vacuum circuit breaker to close: fault on the line; improper operation; operation, closing power supply problem or electrical secondary circuit failure; mechanical failure of the transmission mechanism and operating mechanism of the circuit breaker body. To deal with the failure of the circuit breaker to refuse to close, it is necessary to be good at distinguishing the fault range. First, determine whether the circuit breaker is closed on the pre-voltage fault line to cause tripping. It can be indicated from the impact swing of the meter caused by the short-circuit current during the closing operation and whether there is a lighting lamp. Suddenly darkened, the voltmeter indicated a sudden drop to judge. If it is determined that there is a fault in the line, isolate the fault area and then switch on the circuit breaker. To determine whether it is improper operation, check whether the closing fuse is installed, whether the control switch is reset too fast or not in place, and whether the transfer switch is in the correct position, etc. Check whether the operating closing power supply voltage is too high or too low, check whether the operating closing fuse is blown or has poor contact, check whether the control switch and auxiliary contacts have poor contact, and whether the circuit is broken or wired incorrectly. Check whether the operating mechanism is stuck, and whether the auxiliary contacts and mechanism are adjusted improperly. It is generally caused by the unqualified clearance of the connecting parts of the operating mechanism, and needs to be checked and replaced with new high-hardness qualified parts.

Vacuum circuit breaker opening failure

According to the different causes of the fault, it can be divided into: the vacuum circuit breaker is remotely operated to open; but the vacuum circuit breaker cannot be disconnected. The reasons are: disconnection of the opening operation circuit; disconnection of the opening coil; reduction of the operating power supply voltage; short circuit of the opening coil, reducing the opening capacity; deformation of the opening ejector rod, and jamming during opening, etc. If the tripping failure occurs at the time of the accident, it will lead to the expansion of the accident. Therefore, if the operator finds that the opening and closing indicator light is not on, they should check whether the opening and closing circuit is disconnected in time; the maintenance personnel should pay attention to measuring the resistance of the opening coil during power outage maintenance, and check whether the opening ejector is deformed; The material of the ejector rod is copper and should be replaced with steel; the low-voltage opening and closing test must be carried out to ensure the reliable performance of the vacuum circuit breaker.

The failure of the closing energy storage circuit of the spring operating mechanism of the vacuum circuit breaker

The phenomenon of the failure of the closing energy storage circuit of the spring operating mechanism includes: the opening operation cannot be realized after closing; the operation of the energy storage motor does not stop, etc. The main reason is the upper or lower installation position of the travel switch, and whether the travel switch is damaged. In the case that the closing energy storage is not in place, if an accident occurs in the line, and the vacuum circuit breaker refuses to open, it will lead to the accident leapfrog and expand the scope of the accident; if the energy storage motor is damaged, the vacuum circuit breaker cannot realize opening and closing. The operator should pay attention to observe the closing energy storage indicator light to judge the closing energy storage condition when the switch is reversed. If the above fault occurs, adjust the position of the travel switch to achieve accurate power off of the motor or replace the damaged travel switch. After the maintenance work is completed, the maintenance personnel should perform two opening and closing operations on the spot to confirm that the vacuum circuit breaker is in good condition.

The vacuum circuit breaker opens and closes in different periods, and the bounce value is large

This fault is a recessive fault, and the relevant data can only be obtained through the measurement of the characteristic tester. The reasons for this failure are: the mechanical performance of the vacuum circuit breaker body is poor, after repeated operations, due to mechanical reasons, the bounce value is too large; When the contacts are in contact, there is a deviation between the phases, resulting in a large bounce value in different periods. If the period is different or the bounce value is too large, it will seriously affect the breaking current capability of the vacuum circuit breaker and affect the service life of the vacuum circuit breaker. Since there are many hidden troubles in the split vacuum circuit breaker, the integrated vacuum circuit breaker should be used when replacing the vacuum circuit breaker; during the regular maintenance work, the characteristic tester must be used to test the relevant characteristics and find the problem in time. By analyzing the common faults of vacuum circuit breakers and summarizing their handling experience, power plants can be better guided to do a good job in the operation, maintenance and repair of vacuum circuit breakers, so as to ensure the safe and reliable operation of vacuum circuit breakers.

Other faults

After the circuit breaker mechanism stores energy, the energy storage motor does not stop. At this time, the installation position of the travel switch should be adjusted so that the rocker arm can open the normally closed contact of the travel switch when the rocker arm is at the highest position; the DC resistance of the circuit breaker increases. At this time, it is necessary to adjust the contact opening distance and overtravel of the arc extinguishing chamber; the closing bounce time of the circuit breaker increases. The initial pressure of the contact spring can be appropriately increased or the contact spring can be replaced; if the clearance between the crank arm and the shaft pin exceeds 0.3mm, the crank arm and the shaft pin can be replaced; adjust the transmission mechanism, and use the mechanism to exceed the dead center of the active arm at the closing position When the transmission ratio is small; the mechanism is adjusted to the direction close to the dead center, which can reduce the contact closing bounce; the CT surface of the circuit breaker intermediate box discharges the bracket; the circuit breaker arc extinguishing chamber cannot be disconnected. It is usually caused by the decrease of the vacuum degree of the arc-extinguishing chamber, the decrease of the insulation in the arc-extinguishing chamber, and the unqualified withstand voltage.