Linsheng Analyzes High Voltage Vortex Air Pump Trip Failure
Occasionally, when a high-pressure vortex air pump is used, a closing or tripping problem occurs, and no signal relay is dropped. After the failure of the switching mechanism is eliminated, the cable, the secondary circuit wiring, and the relays and their settings are normal according to the conventional method, and the restart is often successful. After the suspected dcs system soft fault, but changed to operate on the control panel, this phenomenon will still occur. So what are the main reasons and troubleshooting methods for the tripping of high-pressure vortex air pump? The following is a brief introduction by linsheng .
1. Find the reason:
In order to find out the cause of this phenomenon, observe the changes of the meters in the process of closing the switch to confirm what caused it to trip. In the test, the voltmeter monitors the microcomputer trip circuit, the milliampere monitors the differential relays 1cj, 2cj, and the ammeter monitors the thermal protection loop. After the meter is connected, the high-pressure vortex air pump is started. After a period of test, the high-pressure vortex air pump is once started to trip, and the pointer of the milliampere meter is deflected. The other monitoring meters are not responding. The xjl-0025/31 type integrated block signal relay 1xj also acts off, indicating that the trip is caused by the differential protection action.
2, the solution:
The differential protection action first suspects that there is a fault inside the protected device. Through routine inspection, the high-pressure vortex air pump motor and its cable are normal, the differential relay is verified normally, and the polarity of the household booster pump current transformer is correctly connected. After eliminating the cause of equipment failure and wiring error, the differential protection operates during the motor starting process, indicating that the differential current of the differential circuit exceeds the differential relay setting value during this process.
There are two main reasons for the differential current difference current under normal conditions:
First, the current transformer on both sides of the motor has different ratio error, and there is a small difference current, which is less than 5% of the rated current id of the motor.
Second, the difference in the secondary load of the current transformer on both sides of the head and tail will also cause the difference in the ratio, so that there is a difference current.
The current transformer load difference in the differential protection circuit of the high-pressure vortex air pump motor is only the difference of the length of the secondary cable, which is about 50m, and the power consumption of the differential relay is not more than 3va at the rated current, and the secondary load is not heavy. . Check that the first-to-tail current transformers used for differential protection of high-pressure vortex air pump motors are lmzbj-10, b-class 15 times rated current, ratio 600/5, capacity 40 va, fully meet the requirements of secondary load.