Precautions for the Use of Density Relays

Density relay is an important protection and control element in the power system. If the circuit breaker gets out of order, it will cause great economic losses. To ensure the reliability of the circuit breaker operation, it is necessary to frequently monitor the indicators of the circuit breaker. 

The precautions for the use of density relays are as follows:

1. The density relay can only accurately measure the density when the circuit breaker is out of operation and after the internal and external temperatures of the circuit breaker reach equilibrium. If the circuit breaker leaks gas when the circuit breaker is in operation, it will leak more gas than that when the circuit breaker is out of operation due to the effect of temperature rise. Only in this way can the electrical contacts of the density relay be closed.

2. The calibration of density relay is to use a device used to measure gas pressure and the density under various temperatures and pressures. Then compare it with the various pressures simulated by the instrument to observe whether the electrical contact can signal within the specified range of low pressure or lock the circuit breaker, so as to judge the status of the density relay.

3. During the calibration of density relays, it was found that the density relays of several circuit breakers were unqualified, but the unqualified density meters were not found. The standard gas package has a long, thin copper pipe. The unqualified density relay may be caused by the increase of pressure in the standard gas package due to bending or collision of copper pipe during installation or maintenance. It is also possible that the corrugated tube of the density relay is damaged, causing the standard gas package to leak. When the circuit breaker leaks gas, the contacts of C1-L1 and C2-L2 can't be connected, making density relay lose its function, which seriously threatens the safe operation of equipment and even the safety of the system.

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