Guardian 4721 Repair Manual page 47

"V-TYPE" PREPACKAGED
TRANSFER SWITCHES
N1 N2 T1
Figure 6. Transfer Switch Terminal Block
Terminals used on the terminal block are identified as
Utility 1 and 2; Load 1 and 2; 23 and 194.
UTILITY 1 AND 2:
Interconnect with identically labeled terminals in the
generator's control board. This is the "Utility Voltage"
signal to the control board. The signal is delivered to
a "step-down" transformer in the control module
assembly and the resultant reduced voltage is then
delivered to the circuit board. Utility 1 and 2 power is
used by the control board as follows:
• If utility source voltage should drop below a preset
level, control board action will initiate automatic
cranking and startup, followed by automatic
Transfer to the "Standby" source.
• Utility source voltage is used by the control board to
operate a battery "trickle charge" circuit which helps
to maintain battery state of charge during non-oper-
ating periods.
PART 3
T2 23 194
DESCRIPTION & COMPONENTS
LOAD 1 AND 2:
The control board is equipped with a "7-Day
Exerciser" circuit which will start the generator and let
it "exercise" once every seven (7) days on a prese-
lected day and at a preselected time of day. The
"Load 1 and 2" terminals provide power to operate the
exerciser timer clock.
TERMINALS 23 AND 194:
These terminals connect the transfer relay to the gen-
erator's control board. See Section 3.1, "Transfer
Relay".
FUSE HOLDER
The fuse holder holds four (4) fuses, designated as
fuses F1, F2, F3 and F4. Each fuse is rated 2
amperes.
FUSES F1 AND F2:
These two fuses protect the terminal boards "Utility 1
and 2" circuit against overload.
FUSES F3 AND F4:
These two fuses protect the "Load 1 and 2" circuit
against overload.
N1A N2A
F1
F2
N1
N2
Figure 7. The Fuse Holder
SECTION 3.1
T1A T2A
F4
F3
N2
N1
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