molded case circuit breakers - Eaton Canada

246
SWITCHGEAR (TRIP UNIT RETROFIT KITS)
PRODUCT DESCRIPTION
Application
Digitrip RMS trip unit retrofit kits are fully
engineered, field installable retrofit kits that
enable the user to completely replace an
existing tripping system. They are applicable
to (600 VAC) low-voltage power breakers and
are designed for application on both Westinghouse
and non-Westinghouse power
breakers.
Digitrip RMS trip unit retrofit kits provide true
RMS sensing, the most accurate and current
PRODUCT HISTORY
Originally a Westinghouse Product
In the past there have been three types of
automatic control for low voltage power
breakers: electromechanical trip units, solidstate
peak sensing trip units, and state-ofthe-art
true RMS sensing trip units.
Electromechanical Trip Units:
Electromechanical trip units were initially
used in the early 1940s and phased out by all
manufacturers in the mid-1970s.
Westinghouse used these trip devices on types
DA and DK power circuit breakers. They were
also used initially on the DB power circuit
breaker. The electromechanical trip units were
the conventional form of protection on all
manufacturers’ breakers, up until the 1970s.
Electromechanical trip units were composed
of a solenoid, springs, a diaphragm, seals,
and air venting apertures. Three trip units
were required per breaker. Due to age or
harsh environments these devices would fail
or lose calibration. They required a great deal
of preventative maintenance.
PRODUCT HISTORY TIMELINE
state-of-the-art technology for measuring
amperage loads. True RMS sensing removes
the possibility of false tripping due to harmonic
distortion of the power waveform and enables
greater accuracy in selective coordination of
the power distribution system. The microprocessor-based
Digitrip trip unit also allows communications
for remote monitoring to a host
computer or local Assemblies Electronic Monitor
(AEM) via the Integrated Monitoring Protection
and Control Communications (PowerNet)
communication system.
Solid State Peak Sensing Trip Units:
In 1970, the Amptector Trip Unit was
introduced as the standard trip unit on the
Westinghouse type DS power circuit breaker.
The Amptector solid-state trip system provided
much greater accuracy and reliability and
included new features like ground fault (G)
protection, mode of trip indication, and the
ability to perform secondary injection testing.
Electromechanical trip devices immediately
became obsolete, creating a retrofit market.
Amptector retrofit kits were introduced to convert
the type DB breakers that had been factory
equipped with the electromechanical type
trip units.
In 1976, the POW-R-Trip 7 trip unit was introduced
on the Westinghouse SPB insulated case
power circuit breaker. A more simplified version
with only two trip functions, known as the POW-
R-Trip; became available in 1978. Then in 1982
the POW-R Digitrip trip unit became available
and offered on the SPB breakers.
In 1985, RK trip units and retrofit kits were introduced
to provide a solid-state trip unit small
enough to retrofit General Electric breakers as
well as the Westinghouse type DB breakers.
Ratings
Digitrip RMS trip unit retrofit kits are available
for a wide variety of both Westinghouse and
non-Westinghouse low-voltage power breaker
frames. Ratings range from 100 amperes to
4000 amperes. Multitapped CTs, interchangeable
rating plugs, programmable pickup and
time delay settings provide the user with
flexibility.
Peak sensing trip units were an improvement
and provided improved reliability and accuracy.
Only one trip unit was required per
breaker; however, peak sensing trip units
were not able to handle harmonic conditions.
They caused nuisance tripping and unnecessary
downtime.
True RMS Sensing Trip Units:
In 1987, Westinghouse introduced the
Digitrip II RMS trip unit (standard version) for
use on type DS and SPB power circuit breakers.
Digitrip II RMS was the first microprocessor-based
true RMS sensing trip unit.
True RMS trip units enabled the measuring
of current rather than the sensing of current.
Since they are microprocessor-based
digital devices, they are capable of taking
discrete samples of the current waveform in
each phase. By applying a mathematical
algorithm, the current is accurately mapped
out and measured. This method of measurement
provides the ability to adapt to a
changing harmonic content while providing
repeatable and reliable protection.
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Electromechanical Trip Devices (DB Breakers)
Amptector Trip Units and Accessories (DS Breakers)
Amptector Retrofit Kits, Trip Units, and Accessories (DB Breakers)
POW-R-Trip 7 Trip Units (SPB Breakers)
POW-R-Trip Trip Units (SPB Breakers)
POW-R Digitrip I Trip Units (SPB Breakers)
Rating Plugs
RK Retrofit Kits, Trip Units, and Accessories (DB Breakers)
RK Retrofit Kits, Trip Units, and Accessories (GE AK-2A Breakers)
Digitrip II RMS Trip Units (RMS500, RMS600, RMS700, RMS800)
Digitrip III RMS Trip Units (RMS510, RMS610, RMS810, RMS910)
● Westinghouse DA and DK Breakers
● Westinghouse DB Breakers
● Westinghouse DS Breakers
● Westinghouse SPB Breakers
● GE AK-1, AK-2/2A, AK-3/3A, AKR-50, AL-2EO, AL-2-50 Breakers
● Allis Chalmers LA Series Breakers
● ITE K-Line Breakers
● Siemens – Allis Breakers
● Federal Pacific Breakers
● Other Breakers
March 2001