GE Industrial Solutions AF-650 GP Drive Panel - Manual (Page 22)

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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.
Inverter-to-Bypass Delay
The AF 650 GP bypass panels come standard with manual bypass functionality
only. This requires an operator to manually transition power from the drive to
the AC line via the Drive/Off/Bypass selector switch in the event of a drive fault.
When transitioning power to the motor from “Drive” to “Bypass” the operator
must place the switch in the “Off” position for a minimal of 10 seconds. This
delay is to allow for the motor’s rotor flux to decay prior to applying direct AC
line power, which would be out of sync and phase with the flux, resulting in a
potentially damaging current and torque pulsation.
If your bypass panel was ordered with the optional automatic bypass functionality, the
time delay required when transitioning between drive and bypass has been designed
into the panels control logic. For panels rated 30Hp and below at 208 VAC plus 75Hp
and below at 460 VAC & 575 VAC a C-2000™ electronic timer mounted on top of the
bypass contactor (M3). This timer is factory set for a 5-second delay and can be easily
adjusted via a small flat blade screwdriver. For panels greater than 30Hp at 208 VAC
and greater than 75Hp at 460 VAC & 575 VAC a separately mounted time delay relay is
provided to insert the required delay. This timer is factory set for a 10-second delay and
can be easily adjusted via manually turning the dial on the face of the relay. If it is
desired to change the delay setting when transitioning from drive to bypass mode then
consult with the manufacturer of your motor and adjust the time delay accordingly.
DEH40652
– Page 15 AN 11-2021 Rev 06, 12/16/2011
WARNING: The overload relay should not be turned to a higher
setting than allowed by the rules above to allow starting the motor across
the line without tripping. Doing so will compromise the overload protection
which could lead to component damage or fire which could threaten
personnel safety. Refer to NEC for further information.
CAUTION: Failure to insert enough time delay between operation of the
motor from the inverter and operation across-the-line can result in a devastating
torque pulse which can damage your motor, driven load and/or installation. The
AF 650 GP drive does not have a line synchronizing function to permit a smooth
switchover to AC line power, therefore the time delay is the only way to ensure
a safe transition.