TP-6953 7/19 165Section 9 Component Testing and Adjustment
9.10.2 Automatic Opening of the Breaker
The Decision-Makerr 3500 controller opens the
paralleling breaker for any of the following conditions:
D Generator set fault
D Emergency stop
D Start signal removed
D Generator Management signals the generator to stop
and the generator is unloaded
D OFF button pressed. Load enable input is removed
and the generator is unloaded
D Output voltage too high
D Output voltage too low
D Output frequency too high
D Output frequency too low
D Output power too high
D Generator set absorbing power
D Output current too high
D Generator set absorbing reactive power (excitation is
lost)
9.10.3 Synchronization of the Generator
Output to the Paralleling Bus
The synchronizing features of the controller require a
three-phase bus metering connection to ensure that the
line voltage on all three phases can be monitored (to
avoid high reactive power flow due to phase imbalance
immediately prior to breaker closure and to ensure
identical phase rotation).
The synchronizing function operates under the following
conditions:
D Accurate bus sensing connection (to load side of
motor-operated breaker).
D Synchronization Mode set to Active or Check. If the
Sync Mode is set to passive, synchronization is
monitored by not controlled.
D Generator set voltage within tolerance of rated
quantities (all phases).
D Bus voltage within tolerance of rated quantities (all
phases).
D Generator set phase rotation matches that of
paralleling bus (ignored for single phase) alternator
connections.
The Decision-Makerr 3500 controller controls the
speed and voltage as follows:
D The average single- or three-phase RMS amplitude
of the generator set voltage is controlled to match the
average single- or three-phase RMS amplitude of the
paralleling bus.
D The cycle frequency of the generator set is controlled
to match the cycle frequency of the paralleling bus.
D The phase angle between the output waveform of the
generator set and the measured waveform from the
paralleling bus is controlledto0electricaldegrees.
The generator set is considered to be in 0 electrical
degree synchronism when all of these quantities are
within the allowable threshold (window).
The b reaker is signaled to close (in auto mode) after the
generator set has m aintained synchronism with the
paralleling bus for the Dwell Time.
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