Guardian 4721, Repair Manual

Page: 44 / 115

GENERAL
The prepackaged, “V-Type” transfer switch is rated
100 amps at 250 volts maximum. It is available in 2-
pole configuration only and, for that reason, is use-
able with 1-phase systems only.
Prepackaged transfer switches do not have an intelli-
gence system of their own. Instead, automatic opera-
tion of these transfer switches is controlled by a con-
trol board housed in the generator control panel.
In a typical installation, both the utility and standby
power source conductors are connected to the trans-
fer switch, as well as load lines. See Part 1, Section
1.2 for prepackaged interconnections.
TRANSFER SWITCH MAJOR COMPONENTS
Figure 1, below, shows the transfer switch compo-
nents. Major components include the following:
ENCLOSURE
The standard prepackaged, V-Type transfer switch
enclosure is a NEMA 3R type (“NEMA” stands for
“National Electrical Manufacturer’s Association”).
Based on NEMA Standards, the NEMA 3R enclosure
may be defined as one that is intended for outdoor
use primarily to provide a degree of protection against
contact with the enclosed equipment and where
unusual service conditions do not exist.
H
TRANSFER
RELAY
NEUTRAL
BLOCK
ENCLOSURE
FUSE
HOLDER
TERMINAL
STRIP
TRANSFER
MECHANISM
MANUAL
TRANSFER
HANDLE
U
TI
L
NEUTRAL
Figure 1. Exploded View of V-Type Prepackaged Transfer Switch
PART 3
Page 40
“V-TYPE” PREPACKAGED
TRANSFER SWITCHES
SECTION 3.1
DESCRIPTION & COMPONENTS