Contents
Description Page
Automatic transfer switches .................2
Application description .....................2
Switch types .............................4
Transition types ...........................4
Contactor construction .....................5
Automatic transfer switch—open transition .....7
Non-automatic transfer switch—
open transition ...........................10
Automatic transfer switch—closed transition ...13
Wallmount transfer switch logic family ........15
Contactor feature list ......................16
Feature description .......................19
Glossary ................................23
Communications .........................24
Effective February 2013
Supersedes August 2011
Technical Data TD01602018E
Automatic transfer switch (ATS)—
contactor-based
2
Technical Data TD01602018E
Effective February 2013
Automatic transfer switch (ATS)—
contactor-based
EATON CORPORATION www.eaton.com
Automatic transfer switches
Product description
Eaton automatic transfer switches are reliable, rugged, versatile, and
compact assemblies for transferring essential loads and electrical
distribution systems from one power source to another. Eaton’s
contactor-based transfer switch is rated 40–1600A and can be
supplied in separate enclosures for stand-alone applications or can
be supplied as an integral component in the following equipment:
•
MagnumE DS switchgear
•
Pow-R-LineE switchboards
•
Motor control centers (MCCs)
•
Panelboards
For detailed information on the aforementioned equipment,
please see Eaton’s 15th edition of the Consulting Application Guide.
ote:N For information on transfer switch panels, refer to
Volume 2—Commercial Distribution, Tab 5, CA08100003E.
Application description
A transfer switch is a critical component of any emergency or
standby power system. When power is lost from Source 1 (normal),
a transfer switch quickly and safely shifts the load circuit from
Source 1 to Source 2 (emergency). This permits critical loads
to continue running with minimal or no outage. After power
to Source 1 has been restored, the re-transfer process returns
the load circuit to Source 1.
Contactor-based transfer switches are available with different
operational modes, including:
•
Non-automatic
•
Automatic
The power-switching operation of transfer switches may be
separated into the two key categories of:
•
Open transition—break-before-make operation
•
Closed transition—make-before-break operation
The three basic components of a transfer switch are:
•
Power-switching device to shift the load circuits to and from
the power source
•
Transfer logic controller to monitor the condition of the
power sources and provide the control signals to the power-
switching device
•
Control power source to supply operational power to the
controller and switching device
Typical applications
Eaton automatic transfer switches are designed to be operated
in a variety of applications requiring backup power. The most typical
applications are shown below with a utility main source and
generator backup source in Figure 1. Figure 2 shows a generator
normal source and a generator backup source.
Utility–generator
Transfer switches are traditionally applied between a utility and a
generator set for emergency and standby power systems.
Figure 1. Standard Application Utility
���Generator
Generator–generator
Transfer switches are sometimes applied between two generator
sets for prime power use (often in remote installations). In such
applications, source power is periodically alternated between the
generator sets to equally share run time.
Figure 2. Standard Application Generator
–Generator
Se
rvi
ce
Di
sco
nn
ect
Utilit
y
G
Ge
n
e
r
ator
Br
ea
k
er
L
oad
AT
S
G
Generator
Breaker
G
Generator
Breaker
Load
ATS