The use of electrical relays to protect human life and equipment from electrical faults is a mainstream practice, which is essential but often overlooked.Power quality monitoring deviceInstallation design and product selection are crucial for creating an effective system that will execute without occasional issues.
The case involves a batch of protection relays installed in one of the major resorts and theme parks in Singapore. The protective relay has been installed since 2010. The relay forms a part of the system design for protecting the electrical operation of the resort. However, in thePower quality monitoringThis electrical system is troubled by a series of electrical trips that cannot be verified. Over time, some protective relays are completely inoperable. The investigation showed signs of electric burns on the relay.
Electrical consultant JM Pang is hired by the owner to solve ongoing issues. One of the findings is that the electric stroke event has no cause or is a annoying trip. At the same time, the affected protection relay is powered by an auxiliary power supply that is connected to the input before the circuit breaker. This approach may be a cause of relay failure.
It is known that energizing high-power transformers can cause temporary overvoltage conditions. This situation can last for several seconds. In normal practice, when a large power transformer is energized, the downstream circuit will be placed in the closed position and downstream equipment will be protected from temporary overvoltage stress states. However, these stresses will be exposed to relays that are powered on before the circuit breaker. Causing premature failure of the relay.
JM Pang proposed the method of completely replacing installed relays with MH protection relays. Mun Hean Singapore participated in this replacement event. The replacement work is carried out in stages, with the first stage including batch replacement of key MSBs and SSBs, 186 MH protection relays REA200n, and approximately 30 EF18. The second phase was completed in the first quarter of 2018.