GE Industrial Solutions AF-650 GP MultiPulse Drive Panel - Manual (Page 13)

MULTIPULSE DRIVE PANEL
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5 Adjustments
The panel has several user settable
adjustments, which allow it to be tailored
specifically for your 3-phase induction motor.
Setting these adjustments appropriately is an
important factor in ensuring that applicable
safety codes are met and that your bypass
panel, wiring, and motor are adequately
protected. The following list comprises all of
the user adjustable devices/components
inside the panel. The user may wish to have a
copy of NFPA 70-2011 (commonly known as
the National Electric Code or simply NEC)
available for reference when setting these
adjustments.
5.1 Input Fuses
Main input fuses are provided standard with
your panel. In general there are two
configurations that utilize input fuses; 1) input
disconnect with load side separately mounted
fuses and 2) input Fused Disconnect where the
fuses are an integral part of the disconnect. If
your panel was ordered with the circuit
breaker option, the disconnect device and
fuses are replaced by the circuit breaker. The
main input fuses provided with your bypass
panel has been closely coordinated to provide
short circuit protection for the Drive along with
short circuit and over current protection for
the motor. In “Drive” mode of operation, the
fuses only provide short circuit protection due
to the fact that the Drive has inherent over
current protection. In “Bypass” mode of
operation, the fuses provide both short circuit
and over current protection for the motor.
UL listed Class J time-delay fuses are provided
with your panel. These fuses have been sized
in accordance to NEC section 450-52 and
Table 450-152. NEC states fuses of this type
are to be sized at 175% of motor full-load
amps (FLA). Due to the fact that actual motor
FLA along with starting current requirements
vary between manufacturer and motor types
the fuses provided are based on standard NEC
motor data. Verify that actual motor FLA *
1.75 is equal to or greater than the input fuse
amp rating. In the case where the actual
motor FLA * 1.75 is less than the provided
fuses amp rating then smaller fuses may need
to be installed to be in compliance with NEC
section 430-52 and Table 430-152. Please
note exception 1 to NEC 430-52, which states
that where the calculated fuse amp rating
does not correspond to a standard fuse size
the next higher standard fuse size may be
used. In cases where the fuses provided is not
sufficient for the starting current requirements
of the motor, please note exception 2-b to
NEC 430-52. Exception 2-b states the rating of
a time-delay fuse may be increased but shall
not exceed 225% of the motor FLA in any
case. In the case where a larger or smaller
fuse is required, a limiting factor in the bypass
panel may be the fuse holder. The appendices
provide a table for the maximum fuse size
permitted in the existing fuse holder.
Coordinating the fuses for the bypass starter
is the over current protection coordination
between the Class 20/30 overload relay and
the fuse’s over current protection. This
coordination is to avoid nuisance blowing of
fuses. Coordination between the Drive’s short
circuit rating and the fuse’s RMS let through
currents during a short circuit condition has
also been closely evaluated. Changing the
main input fuses may impact one or both of
the above coordination issues. Therefore if it
is necessary to change the input fuses please
consult your preferred fuse supplier and/or
your local GE starter distributor for Type 2 and
overload relay coordination.