United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 85-16: Time/Current Trip Curve Discrepancy of ITE/Siemens-Allis Molded Case Circuit Breaker

                                                        SSINS No.:  6835 
                                                          IN 85-16 
  
                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                    OFFICE OF INSPECTION AND ENFORCEMENT 
                           WASHINGTON, D.C. 20555 
  
                             February 27, 1985 

Information Notice No. 85-16:   TIME/CURRENT TRIP CURVE DISCREPANCY OF 
                                   ITE/SIEMENS-ALLIS MOLDED CASE CIRCUIT 
                                   BREAKER 

Addressees: 

All holders of a nuclear power plant operating license (OL) or a 
construction permit (CP). 

Purpose: 

This information notice is to alert addressees of a potentially significant 
discrepancy pertaining to the time/current trip curves provided with a 
certain molded-case circuit breaker manufactured by the ITE/Siemens-Allis 
Corporation, Philadelphia, Pennsylvania. It is expected that recipients will 
review the information for applicability to their facilities, if 
appropriate, to preclude a similar problem occurring at their facilities. 
However, suggestions contained in this information notice do not constitute 
NRC requirements; therefore, no specific action or response is required. 

Description of Circumstances: 

The staff recently received information from the Seabrook Nuclear Station 
describing a deficiency of the magnetic instantaneous trip element in the 
ITE/Siemens-Allis HE-3-M040 molded-case circuit breaker. These circuit 
breakers were housed in electrical panels supplied by Gould, Inc., Westmin-
ister, Maryland. The deficiency was discovered during the testing of an 
incoming shipment of these breakers. Specifically, the licensee reported 
that testing of an incoming shipment of 15 of these ITE/Siemens-Allis 
circuit breakers revealed that 10 of the 15 failed to pass the instantaneous 
magnetic overcurrent trip test. The pickup current values for the failed 
trip elements were higher than the published ITE time-current curve for this 
type of circuit breaker. However, the licensee also reports that 
approximately 75 of the same model of ITE/Siemens-Allis circuit breakers 
supplied in previous shipments have tested satisfactorily. 

Further investigation into the problem by the manufacturer led to the con-
clusion that the time-current curve provided with the circuit breaker is 
incorrect. The correct time-current trip range should be 600 to 1000 amperes
and not 400 to 700 amperes as previously published by the manufacturer. The 
manufacturer is now reissuing a new set of correct time-current curves that 
reflect the trip range of 600 to 1000 amperes. 



8502250807 
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                                                          IN 85-16  
                                                          February 27, 1985 
                                                          Page 2 of 2 

National Electrical Manufactures Association (NEMA) Standard AB-2 specifies 
that the acceptable trip range during verification testing of the molded 
case circuit breaker is between .75 of the lower limit and 1.4 of the upper 
limit. Therefore, the acceptable trip range for verification testing should 
be 450 to 1400 amperes and not 300 to 980 amperes which was being used by 
the Seabrook, Nuclear Station. A copy of the letter from ITE/Siemens-Allis 
to Gould Inc., discussing details surrounding the deficiency and corrective 
actions regarding the ITE HE-3-M040 molded-case circuit breaker is attached 
for your information and use. 

It is our understanding that Gould Inc. has committed to performing 100% 
inspection on all new or replacement circuit breakers to ensure that 
required time-current trip range limits are being met when tested one pole 
at a time (there are three poles to each molded case circuit breaker). 

It should be noted that the changes in the published time-current trip range
could affect the coordination between breakers at your facility. 

No specific action or written response is required by this information 
notice. If you have any questions about this matter, please contact the 
Regional Administrator of the appropriate regional office or this office. 



                              Edward L. Jordan, Director 
                              Division of Emergency Preparedness 
                                and Engineering Response 
                              Office of Inspection and Enforcement 

Technical Contact:  V. D. Thomas, IE 
                    (301) 492-4755 

Attachments: 
1. ITE/Siemens-Allis letter to Gould Inc. dated January 11, 1985 
2. List of Recently Issued IE Information Notices 
Page Last Reviewed/Updated Tuesday, November 12, 2013