Installation; Standby Electric System - Generac Power Systems GR-210 Operation And Maintenance Manual

INSTALLATION

STANDBY ELECTRIC SYSTEM

A standby electric system may be defined as a system in
which the generator is used to operate critical electrical
loads normally powered by a utility power source when
the utility power source fails or is not present.
• If you are going to use the units to operate electrical
loads in standby system applications, the units may
be used up to their rated capacity. If the total elec-
trical power demanded by all loads in a system is
greater than the rated limit, you can only power
essential or key loads (up to the stated capacity).
• Generac does not recommend installing or operat-
ing a trailer mounted generator indoors. Other
units are available which are better suited for
indoor installations.
• A double throw transfer switch is required in stand-
by electric system applications to prevent electrical
feedback between the generator and the utility
power circuit.
• Figure 1 illustrates a typical standby electric sys-
tem. Figure 2 shows a schematic diagram of such a
system. The transfer switch is used to select which
power supply (generator or utility) will operate load
circuits in such a system. The transfer switch also
prevents load circuits from being connected to both
power supplies at the same time.
• If the installer has not installed a transfer switch
and modified the electric system as shown in
Figure 2, plug critical electrical devices (furnace,
fan, sump pump, water pump, etc.) directly into one
of the generator's output receptacles.
Figure 1 – Typical Standby Electric System
General Information
GR-210 Generator Set
• If the electrician has installed a transfer switch and
a connection box, use a suitable, approved cord set
between the connection box and a suitable genera-
tor receptacle, or between the connection box and
the generator's full capacity terminal studs.
DANGER: If existing electrical circuits in a build-
ing are normally powered by the utility source,
the installer must provide a positive means of
making sure that both power supplies never
feed to the load circuits at the same time.
• Never connect the generator output to any live
building circuits. If the generator is connected to
any existing electrical circuit during a commercial
power outage, a positive method of isolating the two
power supplies must be provided. The usual
method of isolating the circuits is by means of a
double throw transfer switch.
Figure 2 - Simple Standby Electric System
Main Line
Utility
Circuit Breaker
Power
Supply
Utility
Company
Meter
Manual
Transfer
Switch
Generac
Main
Distribution
Load
Panel
Circuits
Emergency
Distribution
Panel
Power Systems, Inc.
®
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