In protective relay-based systems, the time overcurrent protection function is designated by the ANSI/IEEE number code 51. Time overcurrent protection allows for significant overcurrent magnitudes, so long as these overcurrent events are brief enough that the power equipment avoids. In electric power systems and industrial automation, ANSI Device Numbers can be used to identify equipment and devices in a system such as relays, circuit breakers, or instruments. The device numbers are enumerated in ANSI / IEEE Standard C37. These types of devices protect electrical systems and components from damage when an unwanted event occurs, such as an electrical. The overcurrent relay is used to protect the alternator or generator against overloading and which trip the circuit breaker. The short circuit creates heavy fault current through the winding for few milliseconds. ANSI IEEE Standard Device Numbers are below: (the more commonly used ones are in bold) 86T is a Lockout Relay for a.
[PDF Version]