In, a protective relay is a device designed to trip a when a is detected. The first protective relays were electromagnetic devices, relying on coils operating on moving parts to provide detection of abnormal operating conditions such as over-current,, reverse flow, over-frequency, and under-frequency.
[pdf] Electromechanical relays can be classified into several different types as follows: "Armature"-type relays have a pivoted lever supported on a hinge or knife-edge pivot, which carries a moving contact. These relays may work on either alternating or direct current, but for alternating current, a shading coil on the pole is used to maintain contact force throughout the alternating current cycle. Because the air gap between t.
[pdf] ABB's busbar protection is designed for phase-segregated short-circuit protection, control, and supervision of single busbars. A busbar is a strip or bar of copper, brass or aluminum that conducts electricity within a switchboard, a substation or a battery bank. Its purpose is to conduct a substantial current of electricity. Current Differential Protection: This protection method connects CT secondaries in parallel and. The CT Trouble function in the B30 and B90 relays detects this condition by using a low-set differential element, typically set around 10% of the least heavily loaded circuit connected to the bus, that asserts after a settable time delay. The GRB200 can be applied for single, double and ring busbars with or without transfer busbar, one-and-a-half CB (busbar). Busbar protection (BBP): Protection intended to detect and operate to clear faults on a busbar.
[pdf] The various protective functions available on a given relay are denoted by standard. For example, a relay including function 51 would be a timed overcurrent protective relay. An overcurrent relay is a type of protective relay which operates when the load current exceeds a pickup value. It is of two types: instantaneous over current (IOC) relay and definite time overcurrent (DTOC) relay.
[pdf] Updating relay settings is essential to keep up with changes in system parameters such as fault levels, system configuration, and load characteristics. Over time, as power networks evolve and system conditions change, it becomes necessary to update and adjust relay settings to maintain the desired level of coordination and. Electrical systems usually use fuses and circuit breakers to protect electrical equipment such as cables, transformers, motors, and other components. It is ad-vised that any equipment malfunctions, which are typically caused by short cir-cuits, should only impact the area of the system in question. These schemes should allow operators to maximize process availability.
[pdf] 
