IB01602046E
For more information visit: www.eaton.com
Instruction Booklet
Effective: July 2010
Page
3
2-Position Contactor Based
Non-Automatic Transfer Switch
1.2 General Information
Transfer switches are used to protect critical electrical loads
against loss of power. The load’s Source 1 power source is
backed up by a Source 2 power source. A transfer switch is
connected to both the Source 1 and Source 2 power sources and
supplies the load with power from one of the two sources. In the
event that power is lost from Source 1, the transfer switch trans-
fers the load to the Source 2 power source. This transfer is non-
automatic (electrically operated). Once Source 1 power is
restored, the transfer back to the Source 1 power source is non-
automatic (electrically operated). See Figure 2.
Figure 2. Typical Load Transfer Switch Schematic (Contactor
Type).
In the event the Source 1 power source fails, non-automatic
transfer switch will remain connected to the Source 1 power
source. When Source 2 power source with sufficient voltage and
frequency appears, transfer switch can be transferred to Source
2 non-automatically (electrical operation). Conversely, if con-
nected to Source 2 and Source 2 power source fails, non-auto-
matic transfer switch will remain connected to the Source 2
power source. When Source 1 power source with sufficient volt-
age and frequency appears, transfer switch can be transferred to
Source 1 non-automatically (electrical operation).
Non-automatic transfer switches perform the transfer function
and include three basic elements:
1. A power contactor to connect and disconnect the load to
and from either power source.
2. Solenoids to make the transfer of the main contacts from
source to source.
3. Supervisory circuits constantly monitor sources available and
source to which the transfer switch is connected..
1.2.1 Design Configuration
The Eaton contactor based non-automatic transfer switch is a
compact design that uses a power contactor to transfer essential
loads from one power source to another (Figure 3
[
100A
])
.
Figure 3. Typical Power Panel for a 100A Model.
The Eaton contactor based non-automatic transfer switch is
designed with easy installation and simplified maintenance in
mind. Three main panels comprise the contactor based non-
automatic transfer switch design:
1. Power panel;
2. Voltage selection and transformer panel (if required); and
3. Electromechanical logic panel.
Source 1
Source 2
Load
