Page 43 - Nuclear Plant Journal - March April 2013
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Nuclear Plant Journal, March-April 2013
43
Dave Davis
Dave Davis joined NLI in 2007 and
is currently the Site Manager for the
Southeast Region. Dave is responsible
for all sales activities in the southeast
US and is NLI’s
resident expert
on breakers and
switchgear. Prior
to joining NLI,
Dave was the
Circuit Breaker
Program Manager
at PSEG’s Hope
Creek Nuclear
Plant. During
that period he also
served as chairman
of the EPRI Circuit
Breaker Users
Group. Dave’s
nuclear career began in the Navy in
1976 as an electrician on nuclear
submarines and later was commissioned
in the Limited Duty Officer (LDO)
Program. After the Navy, Dave worked
for ABB Service as a field engineer and
QA Manager for the nuclear services
group.
large obsolete and maintenance intensive
legacy breakers, andmodern replacements
that cannot directly replace the legacy
breakers due to the size difference.
Weighing the Options
The situation described above was
faced by PSEG’s Hope Creek Generating
Station a decade ago. Back then Dave
Davis was a component specialist in the
plant’s maintenance department, and
Greg Lichty was one of the station’s
Electrical Maintenance Supervisors.
Hope Creek began commercial operation
in 1986, and in 2002 as the breakers
were nearing time for refurbishment,
the plant began experiencing a growing
number of performance issues with their
low voltage breakers. The breaker OEM
recommended a complete refurbishment
after twenty years of use. With the current
performance issues and the looming need
for more than 250 breaker refurbishments,
Hope Creek began in earnest to develop a
game plan.
Seeking a broader perspective,
PSEG Nuclear commissioned the Elec-
tric Power Research Institute (EPRI) to
conduct a facility lifecycle management
plan, which included an evaluation of its
circuit breakers. In a parallel effort, Nu-
clear Logistics Inc. (NLI) and two other
well-known breaker suppliers were asked
to provide budgetary estimates for refur-
bishment of the legacy breakers as well as
breaker replacement
solutions.
The replacement
breaker solution of-
fered by NLI was the
Square D Masterpact
low voltage breaker.
The Masterpact is
available in an NT
version for appli-
cations up to 800
amps, and a slightly
larger NW version
for applications up
to 3,000 amps. Both
NT and NW break-
ers can be used for AC and DC circuits
and are available with the SureTrip solid
state trip unit for DC applications and
several versions of the Square D Micro-
logic digital trip unit for AC applications.
The Masterpact breaker can also be out-
fitted with all the optional accessories
found on the original legacy breakers. In
short, if Hope Creek was going to replace
their breakers, the Masterpact was a good
choice – except that it wouldn’t fit into
Hope Creek’s switchgear.
The solution offered for the fit issue
was a custom “cradle.” Except when
viewed from the front, the cradle looks
similar to the originally installed circuit
breaker. It has primary and secondary
contacts in the same locations and racks
into the switchgear cubicle in the same
manner. But from the front you see that
the cradle contains a smaller “switchgear
cubicle” with its own set of primary
and secondary contacts designed to
accommodate the Masterpact breaker.
The cradle is rather ingenious – you rack
it into the existing switchgear without
having to make any plant modifications.
Once in place, the cradle now provides the
smaller switchgear cubicle allowing the
smaller modern breaker to be installed.
It turned out that the cost to overhaul
the legacy breakers was higher than
the cost to replace them with new roll
in replacement breaker and cradle
assemblies. From the perspective of
design engineering, changing drawings,
Masterpact breaker and cradle assembly.
