4
Generac
®
Power Systems, Inc.
1.1
GENERATOR
This equipment is a liquid-cooled, engine-driven gen-
erator set. The generator is designed to supply elec-
trical power that operates critical electrical loads
during utility power failure. The unit has been facto-
ry-installed in a weather resistant, all metal enclosure
and is intended for outdoor installation only. Use this
generator as a source of electrical power for the oper-
ation of 120 and/or 240 VAC, single-phase loads.
These models are available. They are rated as follows:
Model 004733-2:
Provides 20,000 watts (20 kW) of single-phase
power.
1.2
TRANSFER SWITCH EQUIPMENT
DESCRIPTION
The pre-packaged transfer switch is designed to use
with pre-packaged standby generator control panels.
It is used for transferring critical loads from a NOR-
MAL (UTILITY) power source to STANDBY (EMER-
GENCY generator) power source. Such a transfer of
loads occurs automatically when the NORMAL power
source fails or is subsequently reduced and the
STANDBY source voltage and frequency have reached
an acceptable level. The transfer switch prevents elec-
trical feedback between two different power sources
(such as the NORMAL and STANDBY sources) and,
for that reason, codes require it in all standby system
installations.
Once the transfer is completed, the STANDBY power
source then powers electrical loads connected to the
transfer switch. When NORMAL source voltage above
an acceptable (preset) level has been restored, circuit
board action in the pre-packaged control panel, initi-
ates retransfer back to the NORMAL power source.
After this retransfer, the circuit board signals to open
the start circuit to the generator, which shuts down
the engine. The circuit board is then “armed” and
ready for the next drop in NORMAL source voltage.
NOTE:
The pre-packaged transfer switch does not have
any kind of electronic controls. It receives signals
solely from circuit board contained in the pre-
packaged control panel of the generator.
1.3
TRANSFER SWITCH RATING
DECAL
Affixed permanently to the transfer switch door is a
RATING DECAL. Use the transfer switch only within
the specific limits shown on the RATING DECAL and
on other decals and labels that may be affixed to the
switch. This prevents damage to equipment, possible
injury to personnel, and provides long and trouble-
free life for the equipment.
When requesting information or ordering parts for
this equipment, make sure to include all information
from the RATING DECAL.
1.4
TRANSFER SWITCH ENCLOSURE
The standard switch enclosure is a National
Electrical Manufacturer’s Association (NEMA) 1 type.
NEMA 1 type enclosures primarily provide protection
against contact with the enclosed equipment and
against a limited amount of falling dirt, and is intend-
ed for INDOOR installation only.
1.5
SAFE USE OF TRANSFER SWITCH
Before installing, operating or servicing this equip-
ment, read the SAFETY RULES (inside front cover).
Comply with all SAFETY RULES to prevent accidents
and/or damage to the equipment. Generac recom-
mends that a copy of the SAFETY RULES be posted
near the transfer switch. Also, be sure to read all
instructions and information found on tags, labels,
and decals affixed to the equipment.
Two publications that outline the safe use of transfer
switches are the following:
• National Electrical Code
• UL 1008, STANDARD FOR SAFETY - AUTOMATIC
TRANSFER SWITCHES.
1.6
TRANSFER SWITCH INSTALLATION
This equipment has been wired and tested at the fac-
tory. Installing the switch includes these procedures:
• Mount ATS enclosure.
• Connecting generator leads.
• Connecting control wiring.
• Connecting any auxiliary contacts (if required).
• Testing functions.
1.7
CONNECTING GENERATOR LINES
Be sure to turn OFF both the NORMAL (UTILI-
TY) and STANDBY (GENERATOR) power sup-
plies before trying to connect power source
and load lines to the transfer switch. Supply
voltages are extremely high and dangerous.
Contact with such high voltage power supply
lines causes extremely hazardous, possibly
lethal, electrical shock.
Wiring diagrams and electrical schematics are pro-
vided in this manual. Power source load connections
are made at a transfer mechanism, inside the switch
enclosure.
DANGER
Section 1 - General Information
Generac Liquid-cooled 20 kW Generator
