General Information - Eaton Cutler-Hammer EGS Serie Mode D'emploi Et D'entretien

O & M Manual for the EGS Automatic
Transfer Switch with RTC-50 Control

1.2 General Information

ATSs are used to protect critical electrical loads against loss of
power. The load's utility power source is backed up by a genera-
tor power source. An ATS is connected to both the utility and
generator power sources and supplies the load with power from
one of these two sources. In the event that power is lost from the
utility power source, the ATS transfers the load to the generator
power source. Once the utility power is restored, the load is auto-
matically transferred back to the utility power source (Figure 2).
Utility
Figure 2. Typical Load Transfer Switch (Contactor) Schematic.
An intelligence system initiates the transfer when the utility power
source fails or falls below a preset voltage. An engine start is
then initiated by the generator and the ATS transfers to the gener-
ator power source when sufficient generator voltage is available.
When the utility power source is restored, the ATS automatically
transfers back and the generator will shut down after a time delay.
In the event the utility power source fails and the generator
power source does not appear, the ATS remains connected to the
utility power source until the generator power source does appear.
Conversely, if connected to the generator power source and the
generator power source fails while the utility power source is still
unavailable, the ATS remains connected to the generator power
source.
ATSs automatically perform the transfer function, and include
three basic elements.
1. Main contacts to connect and disconnect the load to and from
the source of power.
2. Solenoids to make the transfer of the main contacts from
source to source.
3. Intelligence/supervisory circuits to constantly monitor the con-
dition of the power sources and thus provide the intelligence
necessary for the switch and related circuit operation.
IB00405003E - 70-8662
Generator
Load
For more information visit: www.eaton.com
Effective: July 2008
1.2.1 Design Configuration
The Eaton Residential ATS is a rugged, compact design that uti-
lizes power contactors to transfer essential loads from one power
source to another (see Figure 3). The Residential ATS contains
suitable mechanical and electrical interlock switches to eliminate
the possibility of connecting the utility service to the generator
output. In addition, a manual override lever is provided for the
transfer function
DO NOT MANUALLY TRANSFER THE SWITCH WHILE UNDER LOAD.
Figure 3. EGS100SE (100 A).
1.2.2 Optional Service Entrance Feature
The ATS can be ordered in either a standard or service entrance
(SE) configuration. When ordered as an SE, integral overcurrent
protection is built into the switch. Therefore, the ATS can be
installed at the point of service entrance without the need for an
upstream disconnect device.
Instructional Booklet
WARNING
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