IB140015EN
For more information visit: www.Eaton.com
Instructional Booklet
Effective: August 2014
Page
11
ATC-900 Magnum Tranfer Switch O & M Manual
The components comprising the three panels are installed in accor-
dance with the specific requirements of the circuit being controlled.
Each transfer switch is, therefore, tailor-made to a specific applica-
tion.
3.2 Power Compartments
The power compartment consists of a means for making load,
power, and neutral connections. The main contacts and the trans-
fer mechanism are all on one steel frame (Figure 12). The actual
power connections are shown in Figure 13.
Figure 12. Power Case Switching Device.
3.2.1 Main Contacts
The main contacts connect and disconnect the load to and from
the different power sources. High withstand power case switches
are the main contacts for the Source 1 and Source 2 power
sources in standard, unmodified ATSs. Optional integral thermal
and short circuit protection in either or both switching devices is
available (Section 3.6). These continuous duty devices are rated
for all classes of loads. In addition, they have high dielectric
strength, heavy-duty switching and withstand capabilities, and
high interrupting capacity.
3.2.2 Switch Interlocks (Open Transition Only)
Eaton transfer switches are mechanically and electrically inter-
locked to prevent the two sets of main contacts from being closed
simultaneously.
3.2.3 Drawout Interlocks
The standard
closed transition
ATS is not provided with a
mechanical interlock. All bypass switching devices are mechani-
cally interlocked to the drawout mechanism to ensure that the
switching device is always open when connecting or disconnect-
ing it from the line and load stabs when in the bypass mode.
All
open transition
switching devices are mechanically interlocked
to the drawout mechanism to ensure that the switching device is
always open when connecting or disconnecting it from the line
and load stabs.
The switching device will close only in the DISCONNECT, TEST,
and CONNECT positions.
