GE Industrial Solutions ASTAT-XT RVSS PANEL - Manual (Page 21)

DEH40622 - Page 13 AN BL-0350, Rev.01, 08/20/2010
ASTAT-XT RVSS PANEL
6. Troubleshooting
Motor Rotation in Soft Starter and BYPASS Mode
If careful attention to phase rotation is not made during connection of the panel to the three-phase
power supply and motor, then there is only a one chance in four that the motor will rotate correctly in
both Soft Starter and BYPASS modes.
The other three possibilities and the corresponding corrective actions are as follows:
•
Problem: Motor turns correctly in BYPASS mode and incorrectly in Soft Starter mode.
Solution: Swap two of three line power leads connected to the ASTAT’s load side power
terminals (i.e., 2T1, 4T2, 6T3). Do not change any other wiring.
• Problem: Motor turns correctly in Soft Starter mode and incorrectly in BYPASS mode.
Solution: Swap two of three line power leads.
•
Problem: Motor turns incorrectly in both modes.
Solution: Swap two of three motor leads.
Note that if the rotation in BYPASS mode is opposite to the rotation in Soft Starter mode, it is possible
that the panel’s motor overload will trip if a full-speed transition between modes is attempted. This is
due to the large amount of current required to decelerate the motor to a stop prior to accelerating it in
the correct direction.
Circuit Breaker Trip-Level. Possible corrective actions are:
1. Check the trip setting in the rating plug
2. Make sure there is no actual short causing the trip.
3. Try closing the breaker several times. Actual inrush is dependant on
line conditions when the breaker is closed. Closing the breaker when line
conditions are acceptable should prevent tripping.
1. Since actual inrush is dependant on the line conditions, correct the
line condition that is causing excessive inrush.
2. Try another rating plug. Perhaps the tolerances on the one included
with your breaker are unfavorable.
3. Start the motor with Soft Starter mode.
4. For NEMA E motors (super premium efficiency) the NEC 1996 version
will allow a trip setting of 1700% of motor FLA.
Motor Overload Trip Level. Possible corrective actions are:
1. Allow the OL to cool sufficiently between restarts. There is typically a
4 to 1 difference between the operation time of the OLs in their cold
state versus their warm state.
2. Try another OL relay of the same rating. Tolerances on the OLs are
loose, trip times can vary significantly from unit to unit of the same
rating (range of 2 to 1 or more is not uncommon).
3. Reduce the load on the motor during acceleration. Total motor load
during this period is the sum of the accelerating torque plus load
torque. Once motor is up to speed the load can be reapplied.
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