Rockwell Automation 1901 SyncPro - Manual (Page 10)

1-6 Product Description
1901-UM020C-EN-P – June 2013
Typical Synchronous Starter Field Voltage Relay (FVR)
Components (cont.)
When energized, this DC relay indicates that the DC exciter supply
is healthy and producing an adequate level of DC excitation. The
field voltage relay is required to prevent starting the motor unless
DC excitation is available. A field voltage relay is recommended
as the SyncPro does not have the ability to determine the level of
the exciter output voltage. It is needed to prevent unnecessary
starts when synchronization cannot occur.
Equipment Shutdown Relay (ESR) (Component included with
SyncPro)
The ESR relay combines the status of customer supplied protective
and interlock devices to a single contact input on the SyncPro.
When ESR is energized, it is an indication that all external trip
and interlock contacts to the SyncPro are in a "not tripped"
condition. All external trips and interlocks must be wired in series
with the ESR coil in order to be properly addressed by the
SyncPro.
Phase Angle Transducer (Component included with SyncPro)
The phase angle transducer provides a conditioned 4- to 20-
milliamp signal to the analog module of the SyncPro system. The
transducer is factory calibrated to provide a specific output at zero
(0) lagging power factor, at 1.0 or unity power factor, and at zero
(0) leading power factor. These factory settings must not be
altered.
The SyncPro processor scales and interprets this signal to compare
it to the power factor trip set point and to cause a trip to occur if
the power factor drops below the programmed value for more than
the specified power factor trip time delay. If the DC excitation is
lost, a low voltage condition exists, or the motor is being
overloaded to a point where the motor can no longer maintain
synchronous speed, the motor power factor will react by dropping
to a very lagging value. This indicates that the motor is slipping
poles and the controller should be shut down to protect the motor.
The phase angle transducer monitors voltage across lines 1 and 2,
along with the current in line 3 to obtain a power factor reading.
When the reading is below the set points programmed, the SyncPro
will shut down the starter.