molded case circuit breakers - Eaton Canada

March 2001
SWITCHGEAR (TRIP UNIT RETROFIT KITS)
GENERAL INFORMATION
State-of-the-Art Features
Digitrip RMS trip unit retrofit kits come in
several different model types. Among
these types, they provide a variety of
accommodating features (see table below).
True RMS measurement and protection.
Extremely accurate and able to compensate
for harmonic content and disturbances.
Ground fault may be added to an existing
power breaker. Ground fault is offered in a
3-wire and a 4-wire version.
Zone interlocking is available on the short
time and ground fault modes of protection.
This enables enhanced selectivity for
high fault and ground fault coordination
between the main and feeder breakers.
Local monitoring via a display. A red Light
Emitting Diode (LED) display enables the
user to step through and read currents and
energy readings for each phase and
ground.
Communications via the PowerNet system.
This allows all pertinent information,
regarding static and dynamic operation
of the breaker, to be remotely monitored
either by a host computer or IQ AEM. This
facilitates energy management and power
management. Remember:
“If you can’t measure it, you can’t manage it.”
FUNCTIONAL COMPARISONS OF TRIP UNITS
The Packaged Kit
Each Digitrip RMS trip unit retrofit kit
includes a Digitrip trip unit, an auxiliary
CT module, a Direct Trip Actuator (DTA),
qty. (3) current sensors, a rating plug, interconnecting
wiring harnesses, mounting
brackets, copper connectors (when
required), hardware, and installation
instructions. Digitrip RMS retrofit kits are
complete tripping systems engineered
specifically for each breaker type and
frame rating. All kits are designed for field
installation.
Application and Service Condition
In order to ensure that Digitrip RMS trip
unit retrofit kits are successfully applied,
installation must only be done by a qualified
individual.
Appropriate testing must be performed to
qualify the retrofitted breaker prior to placing
the breaker in service. Digitrip RMS
trip unit retrofit kits will provide protection
based on their published time-current
curves when the breaker is properly maintained
and operated in accordance with
the original manufacturer’s specification
and instructions.
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Service Life
The physical structure, the bus assemblies,
and control wiring of switchgear are
normally in good condition. The replacement
of the trip system coupled along
with either refurbishment or reconditioning
of the breaker will prolong the life of
the switchgear and provide modern stateof-the-art
protection.
Availability
Digitrip RMS trip unit retrofit kits are currently
available for select breaker frames
from the following manufacturers:
Westinghouse General Electric
ITE Allis-Chalmers
Siemens-Allis Federal Pacific
Roller Smith
Order Information
In order to obtain the proper kit, the following
information should be provided to your
authorized Cutler-Hammer distributor:
breaker manufacturer, breaker frame
designation, breaker frame rating, breaker
continuous current rating, kit type (see
table below) (i.e., RMS510...RMS810),
modes of protection, sensor rating, rating
plug rating.
Past Technology Features Present Technology
RMS
500
RMS
500
Zone
RMS
600
RMS
700
RMS
800
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Cause of trip LED indicators
Integral self test
Trip reset button
Hardware driven thermal memory
Software driven thermal memory (sel. O/O)
Discriminator circuit on LS and LSG protection modes
Discriminator circuit on LS and LSG protection modes selectable (on/off)
Zone protective interlocking for short time and ground fault modes of protection
Auxiliary contact for long time, short circuit, and ground fault functions
Local display of phase currents
Local display of ground currents
Local display of cause of trip
Local display of energy (MWh)
Local display of peak demand (MW)
Local display of present demand (MW)
Communication with PowerNet communicated data includes:
All display values, trip unit status, high load alarm, cause of trip, rating plug status, breaker status,
reason for breaker status
Trip settings
Power factor
Control via the PowerNet system (open/close)
Voltage phase-to-phase, displayed on trip unit and communicated via PowerNet communications.
Total harmonic distortion (THD); phase A, B, C. Displayed on trip unit and communicated via
PowerNet communications.
Total harmonic distortion per harmonic from the 2nd through the 27th harmonic displayed on trip unit
and communicated via PowerNet communications.
System power factor. Displayed on trip unit and communicated via PowerNet communications.
RMS
510
RMS
510
Zone
RMS
610
RMS
810
RMS
910
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