GE Industrial Solutions AF-650 GP MultiPulse Drive Panel - Manual (Page 16)

MULTIPULSE DRIVE PANEL
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5.4 Drive-to-Bypass Delay
If the AF-600 FP or AF-650 GP panels are
equipped with manual bypass functionality,
then 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. Typically a
delay of three motor AC time constants will be
adequate to ensure that the flux has decayed
to a low enough level to apply AC line power.
An induction motor’s open circuit AC time
constant is dependent on a number of factors
including horsepower rating and number of
poles. Generally speaking the time constant
increases as HP goes up and as the number of
poles goes down.
If your 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.
5.5 Phase loss relay
Set the Phase loss relay to desired system
voltage to avoid any malfunction.
CAUTION: Failure to insert enough time
delay between operation of the motor from
the Drive and operation across-the-line can
result in a devastating torque pulse which
can damage your motor, driven load and/or
installation. The AF-600 FP and AF-650 GP
drives 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.