Specifications

58 Distribution Products Catalog CA08101001E—October 2010 www.eaton.com
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16.4
Tr a n s f er Switches
Magnum-Based Designs
Application Description
Power reliability and power
costs are two issues of
strategic importance in
almost all industry segments.
Businesses have critical
processes that cannot
tolerate a shutdown, while
an extended failure in
many cases could cause
unrecoverable losses. In
addition, significant changes
in the utility industry have
created on-site generation
opportunities for customers
to address their power
reliability and energy cost
concerns. This type of on-site
power generation at or near
the point of consumption is
known as distributed
generation. Market studies
estimate that over 40% of
generation capacity added
in the United States alone
over the next 10 years will be
distributed. A key enabler
of these on-site generation
systems and reliable power
in general is often a closed
transition soft load transfer
switch.
Typical applications for Eaton
closed transition soft load
automatic transfer switches
include industrial processes,
data centers and critical care
facilities. Any location with
critical loads where the
absence of power could
result in lost revenue,
production time or personal
injury should make this
equipment a prime
consideration.
Consider Several
Specific Applications
●
A facility with emergency
or critical power systems
wanting to test their
generator sets without a
power interruption
●
Any industrial, institutional
or commercial business
seeking ways to lower
energy costs by reducing
demand charges, which
can represent over 50% of
an electrical bill
●
Energy service companies
interested in offering
performance-based
solutions to their
customer base
●
Electrical power providers
interested in offering
power reliability solutions
to their customer base in
return for long-term
electrical contracts
The Eaton closed transition
soft load automatic transfer
switch can be applied in new
installations or as a retrofit
to replace an existing open
transition transfer switch. A
number of application issues
should be reviewed. First,
since most generator sets
run on diesel fuel, there are
exhaust emission concerns
to consider. In some markets,
the Environmental Protection
Agency (EPA) limits the
number of hours annually
that a generator set can be
operated. Methods to deal
with such restrictions, should
they present a problem, are
the use of natural gas or
dual fuel (natural gas/diesel
mixture) types of generator
sets. A second issue relates
to electrical utility
interconnection standards.
Many utility companies
require multiple levels of
protective relaying when
a user wishes to parallel to
the utility grid. The cost of
meeting some of these
specifications can be high.
These issues should be
discussed when peak shaving
is being considered.
Features, Benefits and Functions
Sequence of Operations
Automatic Mode
Operation—Transfer
Switch Loss of
Normal Power
The system will continuously
monitor the condition of the
normal power supply. When
the voltage or frequency of
the normal source is sensed
outside the user-adjustable
set points, and after an
adjustable time delay to
override momentary dips and/
or outages, a contact shall
close to initiate a starting of
the emergency or standby
source. Transfer to the
alternate source shall take
place upon attainment of
adjustable pickup voltage and
frequency of the alternate
source.
Return of Normal Power—
Breaker Open Transition
Logic Selected
When normal source has
been restored and is within
the preselected ranges for
voltage and frequency and
after a time delay to ensure
the integrity of the normal
power source, the load shall
be transferred back to normal
source in a break-before-
make transfer scheme. The
generator set will continue to
run for a user-adjustable time
to allow the generator set to
run unloaded for cool down,
after which the engine will be
shut down. Upon completion,
the system will then be ready
for automatic operation.
Return of Normal Power—
Breaker Closed Transition
Logic Selected
When the normal source has
been restored and is within
the preselected ranges for
voltage and frequency, and
after an adjustable time delay
to ensure the integrity of the
normal source, the load shall
be transferred back to the
normal source in a make-
before-brake transfer
scheme.
On completion of the time
delay, the generator-set bus
will automatically synchronize
with the utility service across
the Source 1 (normal)
breaker. When the two
systems are synchronized,
the Source 1 (normal) breaker
will close and the Source 2
(emergency) breaker will
open. The generator set will
continue to run for
a user-adjustable time to
allow the generator set to run
unloaded for cool down, after
which the engine will be shut
down. Upon completion, the
system will then be ready for
automatic operation.
Return of Normal—
Breaker Interchange
(Soft Load) Logic Selected
When the normal source has
been restored and is within
the preselected ranges for
voltage and frequency, and
after an adjustable time delay
to ensure the integrity of the
normal source, the load shall
be transferred back to the
normal source in a make-
before-brake transfer
scheme. On completion of
the time delay, the generator-
set bus will automatically
synchronize with the utility
service across the Source 1
(normal) breaker. When
the two systems are
synchronized, the Source 1
(normal) breaker will close
and the generator set will
gradually transfer all loads
to the utility.
On completion of the load
transfer sequence the
Source 2 (emergency)
breaker will open. The
generator set will continue
to run for a user-adjustable
time to allow the generator
set to run unloaded for cool
down, after which the engine
will be shut down. Upon
completion, the system
will then be ready for
automatic operation.