8
Disconnects
Main disconnect.
The main discon-
nect removes line input power to the
drive and bypass. 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
be in the OFF position before the
option panel door can be opened.
•
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.
•
Disconnect without fuses
. For
user-supplied fuses option.
Figure 1-3. Disconnects
DRIVE
DRIVE
DISCONNECT
DISCONNECT
MAIN
MAIN
DISCONNECT
DISCONNECT
BYPASS
BYPASS
SELECTOR
SELECTOR
SWITCH
SWITCH
•
Main circuit breaker.
A thermal/
magnetic current interrupt device
using an ON/TRIP/OFF/RESET
switch. When in the ON position, a
trip fault removes power from the
drive/bypass 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.
Drive disconnect (optional).
Two-
position (ON/OFF) rotary switch
disconnects main AC line input power
to the drive only.
Bypass selector switch.
The bypass
selector switch is used for either the 2-
contactor or 3-contactor bypass for
EMB units.
Switch Mode Power Supply (SMPS)
The VFD’s logic circuitry is backed up by an
independent panel-mounted switch mode power
supply so that, even if the drive loses power, the
control and communication functions are
maintained. The SMPS converts three-phase AC
input power to 24 VDC control power. Since the
SMPS draws power from all three phases, it offers
immunity protection from most phase-loss and
brown-out conditions. The SMPS is internally
protected from short circuit on its output and three
board-mounted fuses provide additional protection.
The SMPS is not designed for external use and may
take up to 5 seconds to initialize at power-up.
