218 Section 12 Paralleling System Information TP-6953 7/19
Pickup Acceptable Frequency Window. The
generator frequency must remain within this window for
the duration of the Volts Hertz Okay Time Delay before it
is considered to be acceptable. See Figure 12-4.
Note: The Volts Hertz Timer does not run unless both
voltage and frequency are within the window.
Pickup Window
Frequency
MinPickupThreshold
Max Pickup Threshold
Min Dropout Threshold
Max Dropout Threshold
Range: 1.00 – 50.00Hz
Default: 2.50Hz
Figure 12 -4 Pickup Acceptable Frequency Window
Dropout Acceptable Frequency Window. Once the
Voltage and Frequency are considered to be
acceptable, the frequency has to be outside the Dropout
window before it is considered to be unacceptable
again. See Figure 12-5.
Note: Transient Loading may cause the bus frequency
to dip significantly—the paralleling breaker may
trip if the voltage or frequency is perceived to be
outside the dropout window for very long. The
dropout frequency should be set to a large
number to avoid unintended operation of the
system.
Dropout Window
Frequency
Min Pickup Threshold
Max Pickup Threshold
Min Dropout Threshold
Max Dropout Threshold
Range: 1.00 – 50.00%
Default: 30.00Hz
Figure 12-5 Dropout Acceptable Frequency Window
Dead Bus Level. The threshold (in percent of rated
voltage) below which the bus is considered to be dead
(allowing closure without synchronization). If the bus
voltage is measured to be above this threshold, but it is
not within the pickup acceptable voltage window of the
rated bus voltage, the generator will not synchronize or
connect to the bus.
Range: 1.00 – 25.00%
Default: 10.00%
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