United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #: 9708250224


Westinghouse        Energy Systems      Nuclear Services Division

Electric Corporation 

                                        Box 355

                                        Pittsburgh Pennsylvania 15230-


                                        August 19, 1997

U.S.  Nuclear Regulatory Commission

ATTN: Document Control Desk

Washington, DC 20555-0001

Attention: NRC Operations Center

Subject:  Notification of the Potential Existence of Defects Pursuant to


Westinghouse has identified a possible defect in a basic component that

could potentially create a substantial safety hazard and therefore is

deemed reportable under 10CFR21.21.


Three HMCP (Motor Circuit Protectors) molded case circuit breakers were

recently returned to Westinghouse's vendor, Cutler-Hammer when the

utility determined that some of the poles were tripping outside the

setpoint calibration range.  These breakers were verified to be within

specification before shipment as part of the Westinghouse commercial

dedication process, but two tested out of specification before

installation at the plant and one tripped in service when the motor was

started.  All were found with at least one pole out of specification when


HMCP Series C breakers, through magnetic trip action, provide

instantaneous short circuit protection for motor circuits.  These

breakers have ratings from 3 amps to 600 amps in three frame sizes.  The

three breakers returned were all 400 amp.

Safety Significance

The setpoint on an HMCP breaker is selected to provide circuit protection

without tripping on motor starting current.  Several trip ranges are

available for selection on each breaker.  If the setpoint is not within

the selected range, the possibility exists that the circuit will open

preventing a safety-related motor from starting.  However, confidence in

continued system performance can be established by a history of

successful motor start tests even if the breaker was not tested at the

plant prior to installation.

Plant Applicability

The recommended actions apply to all plants that utilize these breakers

for safety-related motor circuits.


NSD-NRC-97-5267                     2                     August 19, 1997

Recommendations/Corrective Action

Although setpoints of HMCP breakers are verified during the commercial

dedication process, Westinghouse will recommend that the setpoint for

breakers in safety-related motor circuits be verified prior to

installation at the plants in addition to periodic surveillance testing. 

Limited feedback from utilities indicates that this verification is a

typical practice.

If you have any questions regarding the notification, please call me at



H. A. Sepp, Manager

Regulatory and Licensing Engineering



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