Specifications
February 2007
16-2
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www.eaton.com
CA08101001E
Transfer Switches
16
Transfer Switch Equipment
Automatic Transfer Switches
Transfer Switch Panels
For more information on “Transfer
Switch Panels,” refer to
Section 4
of
this catalog “Advanced Residential
Products.”
Automatic Transfer Switches
Automatic Transfer Switch Family
Product Description
Eaton’s Cutler-Hammer
Automatic
Transfer Switches are reliable, rugged,
versatile and compact assemblies
for transferring essential loads and
electrical distribution systems from
one power source to another.
Transfer switches can be supplied in
separate enclosures for stand-alone
applications or can be supplied as an
integral component in the following
equipment, see
Table 16-1
.
Table 16-1. Product Description
Application Description
A transfer switch is a critical compo-
nent of any emergency or standby
power system. When the normal
(preferred) source of power is lost,
a transfer switch quickly and safely
shifts the load circuit from the normal
source of power to the emergency
(alternate) source of power. This
permits critical loads to continue
running with minimal or no outage.
After the normal source of power
has been restored, the re-transfer
process returns the load circuit to
the normal power source.
Transfer switches are available with
different operational modes including:
■
Manual.
■
Non-automatic.
■
Automatic.
■
Bypass isolation.
■
Soft load.
■
Maintenance bypass.
The power switching operation of
transfer switches may be separated
into the three (3) key categories of:
■
Open Transition —
Break-before-Make operation.
■
Closed Transition —
Make-before-Break operation.
■
Closed Transition Soft Load —
Both sources are paralleled and
can remain so indefinitely.
The three (3) 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
All Eaton transfer switches are
designed to meet the requirements set
forth by UL
1008, however, all transfer
switches are not created equal. You
can be assured of safe and reliable
operation from all types of transfer
switches that Eaton offers.
Table 16-2. UL 1008 Endurance Testing
Table 16-3. UL 1008 Life Expectancy
UL 1008 Endurance Testing
The importance of specifying a UL 1008
transfer switch can be seen in
Table
16-2
. When specifying any UL 1008
transfer switch, you can be assured
the switch has met and passed the
following endurance testing.
UL 1008 Life Expectancy
Transfer switch applications typically
require a plant exerciser once a week
or once a month.
Table 16-3
demon-
strates the life expectancy operating
the UL 1008 switch once a week for the
life of the switch.
Utility — Generator
Transfer switches are traditionally
applied between a utility and a
generator set for emergency and
standby power systems.
Figure 16-1. Standard Application Utility —
Generator
Product
Type
Section
Reference
Magnum
DS Switchgear
DS
II
Switchgear
Pow-R-Line Switchboards
Motor Control Centers
Panelboards
19
19
15
18
14
ATS
Rating
(Amperes)
Rate of
Operation
Per Minute
With
Current
Without
Current
Total
0 – 300
301 – 400
401 – 800
1
1
1
6000
4000
2000
—
—
1000
6000
4000
3000
801 – 1600
1601 – 4000
0.5
0.25
1500
1000
1500
2000
3000
3000
ATS
Rating
(Amperes)
Minimum
Operations
Per Year
Life
Expectancy
in Years
With
Current
Applied
Life
Expectancy
in Years
Without
Current
Applied
0 – 300
301 – 400
401 – 800
52
52
52
115
76
38
115
76
57
801 – 1600
1601 – 4000
52
52
28
19
57
57
Se
rvi
ce
Di
sco
nn
ect
Utilit
y
G
Ge
n
e
r
ator
Br
ea
k
er
L
oad
AT
S