–31–
M‑3425A Generator Protection Relay
64S 100% Stator Ground Protection by Low Frequency Signal Injection
NOTE
: The Stator Ground Protection function (64S) must be selected when the M‑3425A is initially ordered.
The 100% stator ground fault protection is provided by injecting an external 20 Hz signal into the neutral of the
generator. The protection is provided when the machine is on‑line as well as off‑line (provided that the 20 Hz
generator and relay are powered on.) This scheme requires the following external components in addition to
M‑3425A protection system:
• 20 Hz Signal‑generator (BECO Surface Mount/Flush Part No. 430‑00426)(Siemens 7XT33)
• Band‑pass filter (BECO Surface Mount/Flush Part No. 430‑00427)(Siemens 7XT34)
• 20 Hz Measuring Current Transformer, 400/5 A CT (BECO Par t No. 430‑00428)
(ITI‑CTW3‑60‑T50‑401)
The voltage signal generated by the 20 Hz signal‑generator is injected into the secondary of the generator
neutral grounding transformer through a band‑pass filter. The band‑pass filter passes the 20 Hz signal and
rejects out‑of‑band signals. The output of the 20 Hz band‑pass filter is connected to the V
N
input of the M‑3425A
relay through a suitable voltage divider, that limits the M‑3425A to
O
200 V ac (the voltage generator may be
bypassed if the expected 50/60 Hz voltage during a phase‑to‑ground fault of the generator is
O
200 V.) The
20Hz current is also connected to the I
N
input of the M‑3425A, through the 20Hz current transformer.
When the generator is operating normally (no ground fault) only a small amount of 20 Hz current will flow as
a result of the stator capacitance to ground. When a ground fault occurs anywhere on the generator stator
windings the 20 Hz current will increase. The 64S function will issue a trip signal after a set time delay when
the measured 20 Hz current exceeds the pickup current.
For cases where the Load Resistor (R
N
) is small, the Undervoltage Inhibit should not be enabled, as the voltage
will be small.
The 59N function (90 to 95%) should also be used in conjunction with 64S protection to provide backup.
Summary of Contents for M-3425A
Page 1: ...Instruction Book M 3425A Generator Protection ...
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Page 63: ...M 3425A Instruction Book 1 6 This Page Left Intentionally Blank ...
Page 95: ...M 3425A Instruction Book 2 32 This Page Left Intentionally Blank ...
Page 97: ...M 3425A Instruction Book 3 2 Figure 3 2 IPScom Main Screen ...
Page 123: ...M 3425A Instruction Book 3 28 Figure 3 30 View Sequence of Events Recorder Screen ...
Page 131: ...M 3425A Instruction Book 3 36 This Page Left Intentionally Blank ...
Page 162: ...4 31 System Setup and Setpoints 4 Figure 4 15 IPScom Relay Setup System Dialog Screen ...
Page 183: ...4 52 M 3425A Instruction Book Figure 4 32 Volts Per Hertz 24 Setpoint Ranges ...
Page 187: ...4 56 M 3425A Instruction Book Figure 4 34 Sync Check 25 Setpoint Ranges ...
Page 202: ...4 71 System Setup and Setpoints 4 Figure 4 50 49 Function Overload Curves ...
Page 203: ...4 72 M 3425A Instruction Book Figure 4 51 Stator Thermal Protection 49 Setpoint Ranges ...
Page 215: ...4 84 M 3425A Instruction Book Figure 4 62 Phase Overvoltage 59 Setpoint Ranges ...
Page 239: ...4 108 M 3425A Instruction Book Figure 4 80 Out of Step 78 Setpoint Ranges ...
Page 242: ...4 111 System Setup and Setpoints 4 Figure 4 82 Frequency 81 Setpoint Ranges ...
Page 261: ...M 3425A Instruction Book 5 6 Figure 5 5 Mounting Dimensions for GE L 2 Cabinet H3 and H4 ...
Page 277: ...M 3425A Instruction Book 5 22 Figure 5 14 M 3425A Circuit Board ...
Page 278: ...Installation 5 5 23 Figure 5 15 M 3425A Circuit Board Expanded I O ...
Page 280: ...Installation 5 5 25 Figure 5 17 20 Hz Frequency Generator Housing Panel Surface Mount ...
Page 281: ...M 3425A Instruction Book 5 26 Figure 5 18 20 Hz Frequency Generator Housing Panel Flush Mount ...
Page 282: ...Installation 5 5 27 Figure 5 19 20 Hz Band Pass Filter Housing Panel Surface Mount ...
Page 283: ...M 3425A Instruction Book 5 28 Figure 5 20 20 Hz Band Pass Filter Housing Panel Flush Mount ...
Page 284: ...Installation 5 5 29 Figure 5 21 20 Hz Measuring Current Transformer 400 5 A CT ...
Page 421: ...D 2 M 3425A Instruction Book Figure D 1 Volts Hz 24 Inverse Curve Family 1 Inverse Square ...
Page 422: ...Inverse Time Curves Appendix D D 3 Figure D 2 Volts Hz 24 Inverse Family Curve 2 ...
Page 423: ...D 4 M 3425A Instruction Book Figure D 3 Volts Hz 24IT Inverse Curve Family 3 ...
Page 424: ...Inverse Time Curves Appendix D D 5 Figure D 4 Volts Hz 24IT Inverse Curve Family 4 ...
Page 427: ...D 8 M 3425A Instruction Book Figure D 5 BECO Definite Time Overcurrent Curve ...
Page 428: ...Inverse Time Curves Appendix D D 9 Figure D 6 BECO Inverse Time Overcurrent Curve ...
Page 429: ...D 10 M 3425A Instruction Book Figure D 7 BECO Very Inverse Time Overcurrent Curve ...
Page 430: ...Inverse Time Curves Appendix D D 11 Figure D 8 BECO Extremely Inverse Time Overcurrent Curve ...
Page 437: ...D 18 M 3425A Instruction Book Figure D 15 IEEE Extremely Inverse Time Overcurrent Curves ...
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