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M-3425 Instruction Book
2–10
21 #1 DIAMETER
________ Ohms
21 #1 OFFSET
________ Ohms
21 #1 IMPEDANCE ANGLE
________ Degrees
21 #1 DELAY
________ Cycles
21 #2 DIAMETER
________ Ohms
21 #2 OFFSET
________ Ohms
21 #2 IMPEDANCE ANGLE
________ Degrees
21 #2 DELAY
________ Cycles
Typically the first zone of protection is set to an impedance value
enough in excess of the first external protective section (typically
the unit transformer) to assure operation for faults within that pro-
tective zone. (See Figure 2-4, Phase Distance (21) Coverage.)
A negative or positive offset can be specified to offset the mho
circle from the origin. This offset is usually set at zero. (See Figure
2-5, Phase Distance (21) Function Applied For System Backup.)
The impedance angle should be set as closely as possible to the
actual impedance angle of the zone being protected.
The time delays are set to coordinate with the primary protection of
those overreached zones and, when applicable, with the breaker
failure schemes associated with those protective zones.
The 21 #2 zone settings can be set for the second external section
of protection on the system (typically transmission Zone 1 distance
relays) plus adequate overreach.
Summary of Contents for M-3425
Page 1: ...Instruction Book M 3425 Generator Protection ...
Page 14: ... 13 M 3425 Generator Protection Relay Figure 1 External Connections ...
Page 33: ...x M 3425 Instruction Book This Page Left Intentionally Blank ...
Page 89: ...M 3425 Instruction Book 2 52 This Page Left Intentionally Blank ...
Page 125: ...1 3 A B C M 3425 Instruction Book 4 26 This Page Left Intentionally Blank ...
Page 187: ...M 3425 Instruction Book 6 50 This Page Left Intentionally Blank ...
Page 207: ...M 3425 Instruction Book C 4 This Page Left Intentionally Blank ...
Page 209: ...D 2 M 3425 Instruction Book Figure D 1 Volts Hz 24 Inverse Curve Family 1 Inverse Square ...
Page 210: ...Inverse Time Curves Appendix D D 3 Figure D 2 Volts Hz 24 Inverse Family Curve 2 ...
Page 211: ...D 4 M 3425 Instruction Book Figure D 3 Volts Hz 24IT Inverse Curve Family 3 ...
Page 212: ...Inverse Time Curves Appendix D D 5 Figure D 4 Volts Hz 24IT Inverse Curve Family 4 ...
Page 215: ...D 8 M 3425 Instruction Book Figure D 5 Definite Time Overcurrent Curve ...
Page 216: ...Inverse Time Curves Appendix D D 9 Figure D 6 Inverse Time Overcurrent Curve ...
Page 217: ...D 10 M 3425 Instruction Book Figure D 7 Very Inverse Time Overcurrent Curve ...
Page 218: ...Inverse Time Curves Appendix D D 11 Figure D 8 Extremely Inverse Time Overcurrent Curve ...
Page 223: ...D 16 M 3425 Instruction Book This Page Intentionally Left Blank ...