Power Systems Modernization ª Trip Unit Solutions
The Evolution of Trip Units
A Look at the Numbers
The basic elements of Low Voltage Power Breakers (LVPBs)
are: the mechanism, current-carrying parts, the arc interruption structure, the insulation structure and the tripping
system. One of the major problems with the vast installed
base of LVPBs is the reliability of the tripping system. Why
replace a complete breaker if the problem is in the tripping
system? Between 1940 and 1970, breaker manufacturers used
electromechanical trip units, which lost calibration, required
a great deal of preventative maintenance, and are no longer
supported. Next came the first solid-state trip units. These
were peak-sensing devices that provided greater reliability
and accuracy but were unable to adapt to the changing
world of electrical noise and harmonics.
Losses
Cost of downtime . . . . . . . . . . . . . . . . . . . . . . . . . .$60,000/hour
Downtime as a result of nuisance tripping . . . . .3 hours/year
Total cost of downtime . . . . . . . . . . . . . . . . . . . . . .$180,000/year
Today’s Advanced Technology
The latest technology is true rms sensing, which measures
the average magnitude of the current rather than sensing
the peak current. This method of measurement provides
the ability to adapt to a changing harmonic content,
eliminating nuisance trips while providing repeatable
and reliable protection.
Digitrip RMS Trip Unit Retrofit Kits
Cutler-HammerT DigitripE RMS trip unit retrofit kits
from Eaton’s Electrical business are fully engineered, field
installable, and designed to completely replace an existing
trip system. These kits provide modern state-of-the-art
protection using the latest rms technology. Over 150 kits
are available for various manufacturers’ low voltage
breakers, with each kit specifically engineered for use
on a particular breaker frame.
Digitrip retrofit kits represent a cost-effective alternative to
replacing a complete breaker or switchgear assembly. Once
installed, they reduce costly downtime by increasing system
reliability. Downtime is further reduced with the addition of
communications that results in less time to locate and troubleshoot faults. As an alternative to utilizing local networks,
breaker information can be communicated back to our 24/7
Instant Response CenterSM (IRC) monitoring service where
power quality and power systems experts will monitor your
electrical distribution and related systems.
Cost to Implement
Installed retrofit trip system
with communications . . . . . . . . . . . . . . . . . . . . . . .$4,252
Typical payback . . . . . . . . . . . . . . . . . . . . . . . . . . .0.43 months
Note: Calculation includes one hour of scheduled downtime
for installation.
Business/Industry
Interruption Costs
Cost
Paper Industry
$10,000 – $30,000/event
Textile Industry
$10,000 – $40,000/event
Data Processing
$10,000 – $40,000/event
Plastics Industry
$10,000 – $50,000/event
Semiconductor Industry
$10,000 – $50,000/event
Automotive Manufacturing
$15,000/event
Air Traffic Control
$15,000/minute
Office Building
$22,000 per 500 kVA of critical load
Broadcast Facility
$100,000/30 minutes
A Case Study in Savings
A U.S. Department of Defense (DOD) facility in Norfolk, VA,
which provides electricity to the fleet ships when they are
in port, was experiencing nuisance tripping from their low
voltage power breakers. The DOD had no way of identifying
where the trip occurred or what caused the trip. The
switchgear was located in underwater concrete vaults,
making complete replacement a very costly option.
Eaton provided hundreds of rms sensing Digitrip retrofit kits to
the DOD for several different manufacturers’ low voltage
power breakers. The kits included communications capabilities. As a result, the DOD has eliminated the nuisance tripping.
When a breaker trips, the DOD can immediately locate and
troubleshoot the fault, reducing further downtime.
Integrated Solutions Summary
Our engineering professionals have the expertise and experience
to correctly apply Digitrip retrofit kits to a variety of low voltage
power breakers, thereby increasing reliability and offering
improved system coordination.
ª Asset Optimization: Outsource the responsibility for the
electrical distribution system and associated equipment to
Eaton - Electrical Services & Systems. Offerings involve cost
savings and performance guarantees for greater focus on
the core business. Asset Optimization uses all the tools and
capabilities within the other service platforms, resulting in
improved reliability, life expectancy and overall cost.
ª Knowledge Management: Collect and transform your system
data to useful knowledge; allow for proactive planning, energy
management, optimized decision making, failure prediction and
ultimately, cost savings.
ª Integrated Project Solutions: Engineering, design, procurement,
installation and commissioning of power systems equipment; a
total turnkey approach.
ª Power Systems Engineering Solutions: Power systems automation, design engineering, training, predictive diagnostics, power
quality and power systems studies/analysis to decrease costs
and increase productivity.
ª Power Systems Modernization: Keep systems operating at peak
efficiency, reliability and safety; extend the life of the electrical
asset through equipment life extension and upgrade solutions
utilizing new technologies.
For further information, please visit our Web site at:
www.EatonElectrical.com and click on Support, then Services &
Systems, or contact your nearest Eaton - Electrical Services &
Systems office.
For emergency service, call 1-800-498-2678 and ask for the office
nearest you.
Cutler-Hammer is a federally registered trademark of Eaton Corporation.
ª New Equipment Services: Installation, testing and commissioning of virtually any electrical equipment.
ª Field Services: Power system and equipment service, maintenance programs, testing, upgrades and Aftermarket solutions;
24/7 emergency service; crisis response and disaster recovery.
Eaton Electrical Inc.
1000 Cherrington Parkway
Moon Township, PA 15108
United States
tel: 1-800-525-2000
www.EatonElectrical.com
© 2004 Eaton Corporation
All Rights Reserved
Printed in USA
Publication No. SA02727003E / Z2790
August 2004