Page 10 - Practical Power System and Protective Relays Commissioning

4 Practical Power System and Protective Relays Commissioning

27 Under voltage relay
37 Under current or under power relay
40 Field relay
41 Field circuit breaker
42 Running circuit breaker
46 Reverse phase or phase balance current relay
47 Phase sequence voltage relay
49 Machine or transformer thermal relay
50 Instantaneous overcurrent or rate of rise relay
51 AC time overcurrent relay
52 AC circuit breakers
55 Power factor relay
59 Overvoltage relay
63 Liquid or gas pressure, level, or flow relay
65 Governing equipment which controls the gate or valve opening of a
prime mover
67 AC directional overcurrent relay
72 DC circuit breakers
76 DC overcurrent relay
79 AC autoreclosing relay
81 Frequency relay
85 Carrier or pilot-wire receiver relay
86 Locking-out relay
87 Differential relay
89 Line switch
94 Tripping relay
There are symbols for switchgear and protective devices as shown in
Fig. 1.2.