Non-Bypass Component Functions; Power Fusing; Reactors; Disconnects - Danfoss VLT FC Series Operating Instructions Manual

Non-bypass Component Functi...

7 Non-bypass Component Functions

7.1.1 Power Fusing

For all option panel power fuses, use the specified fuse or
an equivalent replacement only. See the fuse ratings label
on the inside cover of the unit for option panel fuse
ratings.
Main fusing
Main fuses are located ahead of the drive and bypass.
Main fuses are designed to protect the circuitry within the
bypass panel but is not adequate to protect the drive.
Main fuses are dual-element, time-delay types and mount
inside the bypass enclosure.
Drive fusing
7 7
Drive fuses are located ahead of the drive and are a fast-
acting type. Drive fuses are standard in two-contactor and
three-contactor bypasses. A fuse/disconnect enclosure may
be used if no options other than a fuse block and
disconnect switch are required.
100,000 amp SCCR
The option panel is at least 5,000 amps short-circuit
current rating (SCCR). An additional 100,000 amp SCCR is
available as an option. See the panel label for SCCR rating.

7.1.2 Reactors

Input line reactor
This is a 3-phase reactor, mounted on the input to the
option panel This lowpass reactor adds 3% impedance on
the line input. The impedance filters noise from the line
input to the drive along with the return drive noise on the
line. It is not in operation when running across the line.
Output dU/dt filter
This is a 3-phase reactorcapacitor- resistor combination.
Mounted in series with the output of the drive, it functions
to reduce the magnitude of voltage spikes related to PWM
wave forms generated by the drive. It allows the use of
longer motor leads and reduces insulation stress on
motors without interphase insulation. It is not connected
to the motor when running across the line.

7.1.3 Disconnects

Main disconnect
The main disconnect removes line input power to the
drive and option panel. A main disconnect is available in
four options.
•
Fused disconnect
Two-position (ON/OFF) rotary switch, padlock
compatible, with three fuses, one on each phase,
built into the switch. For safety, the switch must
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Option Panel Operating Instructions
•
•
•
Drive disconnect
Two-position (ON/OFF) rotary switch disconnects main AC
line input power to the drive only.

7.1.4 Motor Options

The drive with bypass has three motor combination
options available for drive control or for running in bypass:
single motor, dual motor, or contact motor select.
Single Motor Option
General information
The single motor option is when a drive is running one
motor or the motor is operating in bypass mode. The drive
and motor are normally the same hp. The FLA of the
motor must be less than or equal to the maximum output
current of the drive.
Before enabling single motor operation
•
Function
There are no special functions related to single motor
option.
Dual motor option
General information
The dual motor option is available for one drive running
two motors at the same time or both motors running in
bypass. The motors may be of the same or different hp,
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MG14I102 - VLT is a registered Danfoss trademark
be in the OFF position before the option panel
door can be opened or fuses removed.
Disconnect with fuses
Two-position (ON/OFF) rotary switch, padlock
compatible, with a fuse block mounted separately
from the disconnect. Three fuses, one on each
phase, are located on the fuse block. For safety,
the switch must be in the OFF position before
the option panel door can be opened.
Main circuit breaker
A thermal/magnetic current interrupt device
using an ON/TRIP/OFF/RESET switch. When in the
ON position, a high current fault removes power
from the drive/option panel circuit and the switch
moves to the TRIP setting. It must be moved to
the RESET position momentarily after the fault
has been cleared to reset the circuit breaker.
Disconnect without fuses
For user-supplied fuses option.
Complete the start-up procedure to verify motor
rotation direction is correct and that the system is
ready in all respects for continuous full speed
operation in bypass.