4–109
System Setup and Setpoints – 4
81 Frequency
The Frequency function (81) provides either
overfrequency or underfrequency protection of
the generator. It has four independent pickup and
time delay settings. The overfrequency mode is
automatically selected when the frequency setpoint
is programmed higher than the base frequency (50
or 60 Hz), and the underfrequency mode selected
when the setpoint is programmed below the base
frequency. Ranges and increments are presented
in Figure 4-82.
The steam turbine is usually considered to be more
restrictive than the generator at reduced frequencies
because of possible natural mechanical resonance
in the many stages of the turbine blades. If the
generator speed is close to the natural frequency
of any of the blades, there will be an increase in
vibration. Cumulative damage due to this vibration
can lead to cracking of the blade structure.
Sample settings of the 81 function are shown
in Figure 4-81. The frequency functions are
automatically disabled when the input voltage
(positive sequence) is very low (typically between
2.5 V and 15 V, based on the frequency.)
The 81 function should be disabled using breaker
contact when the unit is offline.
These magnitude and time settings describe
a curve (as shown in Figure 4-81, Example of
Frequency (81) Trip Characteristics) which is
to be coordinated with the capability curves of
the turbine and generator as well as the system
underfrequency load-shedding program. These
capabilities are given by a description of areas of
prohibited operation, restricted time operation, and
continuous allowable operation.
The underfrequency function is usually connected
to trip the machine whereas the overfrequency
function is generally connected to an alarm.
In order to prevent mis–operation during switching
transients, the time delay should be set to greater
than five (5) cycles.
81 #1 PICKUP
Hz
81 #1 DELAY
Cycles
81 #2 PICKUP
Hz
81 #2 DELAY
Cycles
81 #3 PICKUP
Hz
81 #3 DELAY
Cycles
81 #4 PICKUP
Hz
81 #4 DELAY
Cycles
Содержание M-3425A
Страница 1: ...Instruction Book M 3425A Generator Protection ...
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Страница 39: ...800 3425A SP 10MC2 07 12 2001 Beckwith Electric Co All Rights Reserved Printed in U S A 01 67 04 25 03 ...
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Страница 73: ...M 3425A Instruction Book 2 10 Path Monitor Primary Metering Status Figure 2 4 Primary Metering Status Screen ...
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Страница 97: ...M 3425A Instruction Book 3 2 Figure 3 2 IPScom Main Screen ...
Страница 103: ...M 3425A Instruction Book 3 8 Path Monitor Primary Metering and Status Figure 3 9 Primary Metering Status Screen ...
Страница 105: ...M 3425A Instruction Book 3 10 Path Monitor Secondary Metering and Status Figure 3 10 Secondary Metering Status Screen ...
Страница 123: ...M 3425A Instruction Book 3 28 Figure 3 30 View Sequence of Events Recorder Screen ...
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Страница 162: ...4 31 System Setup and Setpoints 4 Figure 4 15 IPScom Relay Setup System Dialog Screen ...
Страница 180: ...4 49 System Setup and Setpoints 4 Table 4 5 Impedance Calculation Figure 4 30 Phase Distance 21 Setpoint Ranges ...
Страница 183: ...4 52 M 3425A Instruction Book Figure 4 32 Volts Per Hertz 24 Setpoint Ranges ...
Страница 187: ...4 56 M 3425A Instruction Book Figure 4 34 Sync Check 25 Setpoint Ranges ...
Страница 202: ...4 71 System Setup and Setpoints 4 Figure 4 50 49 Function Overload Curves ...
Страница 203: ...4 72 M 3425A Instruction Book Figure 4 51 Stator Thermal Protection 49 Setpoint Ranges ...
Страница 215: ...4 84 M 3425A Instruction Book Figure 4 62 Phase Overvoltage 59 Setpoint Ranges ...
Страница 219: ...4 88 M 3425A Instruction Book Figure 4 65 Overvoltage Neutral Circuit or Zero Sequence 59N Setpoint Ranges ...
Страница 236: ...4 105 System Setup and Setpoints 4 Figure 4 77 Residual Directional Overcurrent 67N Setpoint Ranges ...
Страница 239: ...4 108 M 3425A Instruction Book Figure 4 80 Out of Step 78 Setpoint Ranges ...
Страница 242: ...4 111 System Setup and Setpoints 4 Figure 4 82 Frequency 81 Setpoint Ranges ...
Страница 261: ...M 3425A Instruction Book 5 6 Figure 5 5 Mounting Dimensions for GE L 2 Cabinet H3 and H4 ...
Страница 277: ...M 3425A Instruction Book 5 22 Figure 5 14 M 3425A Circuit Board ...
Страница 278: ...Installation 5 5 23 Figure 5 15 M 3425A Circuit Board Expanded I O ...
Страница 280: ...Installation 5 5 25 Figure 5 17 20 Hz Frequency Generator Housing Panel Surface Mount ...
Страница 281: ...M 3425A Instruction Book 5 26 Figure 5 18 20 Hz Frequency Generator Housing Panel Flush Mount ...
Страница 282: ...Installation 5 5 27 Figure 5 19 20 Hz Band Pass Filter Housing Panel Surface Mount ...
Страница 283: ...M 3425A Instruction Book 5 28 Figure 5 20 20 Hz Band Pass Filter Housing Panel Flush Mount ...
Страница 284: ...Installation 5 5 29 Figure 5 21 20 Hz Measuring Current Transformer 400 5 A CT ...
Страница 421: ...D 2 M 3425A Instruction Book Figure D 1 Volts Hz 24 Inverse Curve Family 1 Inverse Square ...
Страница 422: ...Inverse Time Curves Appendix D D 3 Figure D 2 Volts Hz 24 Inverse Family Curve 2 ...
Страница 423: ...D 4 M 3425A Instruction Book Figure D 3 Volts Hz 24IT Inverse Curve Family 3 ...
Страница 424: ...Inverse Time Curves Appendix D D 5 Figure D 4 Volts Hz 24IT Inverse Curve Family 4 ...
Страница 427: ...D 8 M 3425A Instruction Book Figure D 5 BECO Definite Time Overcurrent Curve ...
Страница 428: ...Inverse Time Curves Appendix D D 9 Figure D 6 BECO Inverse Time Overcurrent Curve ...
Страница 429: ...D 10 M 3425A Instruction Book Figure D 7 BECO Very Inverse Time Overcurrent Curve ...
Страница 430: ...Inverse Time Curves Appendix D D 11 Figure D 8 BECO Extremely Inverse Time Overcurrent Curve ...
Страница 437: ...D 18 M 3425A Instruction Book Figure D 15 IEEE Extremely Inverse Time Overcurrent Curves ...
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