Selected ANSI Device Numbers

1 – Master Element

12 – Overspeed Device

14 – Underspeed Device

27 – Undervoltage Relay

28 – Flame detector

30 – Annunciator Relay

32 – Directional Power Relay or Reverse Power Relay

41 – Field Circuit Breaker

50 – Instantaneous Overcurrent Relay

51 – AC Inverse Time Overcurrent Relay

52 – AC Circuit Breaker

59 – Overvoltage Relay

67 – AC Directional Overcurrent Relay

68 – Blocking Relay

72 – DC Circuit Breaker

76 – DC Overcurrent Relay

78 – Phase-Angle Measuring Relay or "Out-of-Step" Relay

79 – AC Reclosing Relay

81 – Frequency Relay

82 – DC Reclosing Relay

86 – Lockout Relay

87 – Differential Protective Relay

94 – Tripping or Trip-Free Relay