Name the device name and its function and uses for the follo

Name the device name and its function and uses for the following devices:

87, 50, 51, 27, 32, 46, 21, 86, 67

Solution

These are ANSI device numbers which signifies the features of a protective device such as a relay or circuit breaker.These types of devices protect electrical systems and electroniccomponents from electrical faults. These numbers are used to indicate the function of device as follows:

87 – Differential Protective Relay

50 – Instantaneous Overcurrent Relay

51 – AC Inverse Time Overcurrent Relay

27 – Undervoltage Relay

32 – Directional Power Relay or Reverse Power Relay

46 – Reverse-phase or Phase-Balance Current Relay

21 – Distance Relay

86 – Lockout Relay/Master Trip

67 – AC Directional Overcurrent Relay

67N- Directional Earth Fault relay