Rockwell Automation 1901 SyncPro - Manual (Page 40)

5-2 Programming
1901-UM020C-EN-P – June 2013
Set Points (cont.) Set Point 1 • Minimum % Synchronous Slip Frequency
This set point determines the percentage of synchronous speed at
which the DC voltage is to be applied by the field contactor. The
SyncPro monitors the frequency of the induced voltage across the
discharge resistor during starting. When this frequency indicates
that the motor has achieved the desired subsynchronous speed at
which it is allowable to synchronize, the SyncPro energizes the
coil of the field contactor. The SyncPro ensures that the application
of the field contactor coincides with the rising edge of the induced
voltage waveform which makes for a smooth transition. If the
motor pulls into synchronism due to reluctance torque, the
SyncPro will detect no pulses and then will apply DC voltage to
the field after a one second delay.
Allowable Range: 2 to 10 % (slip at which synchronization
will occur as a percentage of
synchronous speed)
Factory Default Setting: 5% (95% speed)
Typically set at: 5%
Set Point 2 • Power Factor Trip
As discussed earlier, power factor can be used to determine if a
motor has pulled out of synchronism due to loss of excitation,
overloading or a severe undervoltage. At this time, the motor
should be taken off line to protect the stator and field windings.
Allowable Range: 60 to 100 (% of unity)
Factory Default Setting: 80 (0.8 lagging power factor)
Set Point 3 • Power Factor Trip Time Delay
Once it is determined that the motor has a lagging power factor
due to a pullout condition, the trip condition can be time delayed to
allow the motor a brief opportunity to pull back into synchronism.
Allowable Range: 0 to 100 s (0.01 second units)
Factory Default Setting: 50 s (0.50 second delay)