Numbers Flashcards
(24 cards)
21
Impedance- A relay that monitors current and voltage to determine when a fault occurs.
25
Synchronizing- A relay in some way is related to the closing of a CB with sources on both sides with certain limits of synchronization
27
Under-voltage- A relay testing that will perform some function when the voltage drops to a present value or in some cases to zero
30
Alarm- A relay that is associated with an alarm or an annunciation
51
Over-Current- A relay that is present to operate at a certain amount of current with a time delay that varies inversely with current
50
Instantaneous over current
59
Over-Voltage- A relay that is present to operate when the voltage reaches a predetermined (high) value
63
Pressure- A relay that has to do with pressure, an alarm on a pneumatic CB and sudden pressure on a transformer
64
CB fault- A relay that is set to operate for a flash-over to ground on a pole, head or column of air or gas CB
67
Directional- A relay which has directional characteristics or is used with another relay that has directional characteristics. The current or power must be flowing in a certain direction before the relay scheme will operate
79
Reclosing- A relay that is associated with the automatic reclosing of equipment. Such relays normally have no targets
86
Lockout- A multiple-contact relay (HEA) which is used to trip and lock out various equipment (Aux)
87X
Differential lockout relay
551X
Breaker failure lockout relay
87
Differential- A relay in some way is associated with differential protection of equipment (buses, transformers, etc…)
94
Transfer trip- A relay that is associated with the remote tripping of equipment
97
Carrier- Receiver relay that denotes that the carrier protective relaying has operated and no blocking signal was received
26
Temperature
71
Level Switch
43
Supervisory
29
Reclosing selection switchj
81
Under frequency
80
Liquid or gas flow
101
Control switch
