Bell & Gossett 176R0649C Technologic 502 Series Pump Controller - Manual (Page 8)

8
Disconnects
Main disconnect. The main disconnect removes
line input power to the controller and bypass. A main
disconnect is available in two options. For safety, the
switch must be in the OFF position before the panel
door can be opened. (See Figure 1-4.)
• Main disconnect with built-in
fuses. Two-position (ON/OFF) ro-
tary switch, with three built-in fuses,
one on each phase.
• Main disconnect with separate
fuses. Two-position (ON/OFF)
rotary switch with a fuse block
mounted separately from the
disconnect. Three fuses, one on
each phase, are located on the fuse
block.
Drive disconnect. Two-position (ON/OFF) rotary
switch disconnects main AC line input power to the
drive only.
Motor Alternation Selector Switch
The B3 option includes contactor motor selection. It
provides motor alternation with one drive alternating
operation between two motors. The panel mounted
Motor 1/Auto/Motor 2 selector switch provides local
control of either motor along with an auto setting that
allows auto selection through the master drive.
Figure 1-4. Disconnects
Power Fusing
Two types of fusing are available for the units—main
and drive fusing. For all power fuses, use the speci-
fied fuse or an equivalent replacement only. See the
fuse ratings label on the inside cover of the unit for
ratings.
Main fusing. Main fuses are located ahead of the
drive. Main fuses are designed to protect the circuitry
within the panel but are not adequate to protect the
drive. Main fuses are dual-element, time-delay type
and mount inside the bypass enclosure.
Drive fusing. Drive fuses are located ahead of the
drive and are a fast-acting type. Drive fuses are stan-
dard in two-contactor and three-contactor bypasses.
A fuse/disconnect enclosure may be used if no op-
tions other than a fuse block and disconnect switch
are required.
DRIVE
DISCONNECT
DRIVE
OPTION PANEL
BACKPLATE
MAIN
MOUNTING PANEL
DISCONNECT