Protection relays such as Over Current Relays or Earth Fault Relays are used in Electrical Panels to provide a safeguard against Electrical Shocks and Burns. Very simply, these Protection relays measure the current flowing in and out of an installation. When there is an imbalance in the current in and current out, the relay will send a signal to the Main Switch to Open, thus interrupting the flow of leakage current and potentially saving lives.
Some relays monitor when the current goes beyond a preset value, these are called overcurrent relays. This causes the relay to open the main Switch (called a Circuit Breaker) when the current goes high. This can prevent electrical fires as well as serious short circuits and electrocution.
When an electrical fault occurs, people can get electrocuted and die because the return current flows through their body (stopping their heart) and out to the Ground, thus the current in is not equal to the current out. If the relay detects this, it can stop the current flow by opening the switch, thus saving the life of the person being electrocuted. The relay must act in milliseconds and automatically. That is why the Electricity Regulations (1994) states very clearly in Regulation 110 that all relays must be tested and calibrated once in 2 years. #protectionrelays, #electricalsafety, #onealphagroup, #relaycalibration, #earthfaultrelay, #overcurrentrelay,