United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 97-12: Potential Armature Binding in General Electric Type HGA Relays

                                 UNITED STATES
                         NUCLEAR REGULATORY COMMISSION
                     OFFICE OF NUCLEAR REACTOR REGULATION
                          WASHINGTON, D.C. 20555-0001

                                March 24, 1997


NRC INFORMATION NOTICE 97-12:  POTENTIAL ARMATURE BINDING IN GENERAL           
                              ELECTRIC TYPE HGA RELAYS 

Addressees

All holders of operating licenses or construction permits for nuclear power
reactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to alert addressees that two General Electric (GE) type HGA relays
failed to reposition when the coils were deenergized.  It is expected that
recipients will review this information for applicability to their facilities
and consider actions, as appropriate, to avoid similar problems.  However,
suggestions contained in this information notice are not NRC requirements;
therefore, no specific action or written response is required.

Description of Circumstances

On May 15, 1996, Commonwealth Edison Company (ComEd) reported that two
12HGA17S63 relays installed in the reset logic for the primary containment
isolation system at its Dresden Nuclear Power Station, Unit 3, failed to
reposition when operators removed power to the relay coils.  The relay
failures resulted in a failure to seal in isolation signals to a main steam
isolation valve and a recirculation sample isolation valve when operators
reset a scram signal after a reactor scram.  Consequently, the valves opened
when the scram was reset.  Operators used the manual switches in the control
room to reclose the valves.  ComEd personnel removed the relays and
disassembled them in an attempt to determine the root cause of the problem. 
When a root cause could not be determined, the failed relays were sent to GE
Power Management (GE PM), located in Malvern, Pennsylvania, for a thorough
investigation.

Discussion                                                                    



GE PM reassembled the failed relay submitted by ComEd for a root cause
analysis and it operated properly, both mechanically and electrically.  When
GE PM performed a dimensional analysis of the critical parts, however, the
assembly hole of the molded contact support was found to be slightly off-
center.  GE PM stated that the mold that produces the contact support was
reworked in 1990 to correct for mold wear and to bring the parts within the
design drawing tolerances.

9703200229.                                                            
                                                            IN 97-12
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                                                            Page 2 of 2


GE PM issued Relay Service Advice Letter 516.1 on October 25, 1996, to alert
customers that HGA relays manufactured between January 1989 and June 1991 may
have marginal armature-to-contact support clearance and may be susceptible to
armature binding.

However, some licensees may have procured the relays as commercial-grade, or
received them as basic components from a dedicating entity and, therefore, may
not have received the attached GE relay service advice letter.  Consequently,
some licensees may not have had the opportunity to evaluate the information in
accordance with 10 CFR Part 21. 

This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.


                                                signed by M.M. Slosson

                                    Thomas T. Martin, Director
                                    Division of Reactor Program Management
                                    Office of Nuclear Reactor Regulation

Technical contacts:  K. Naidu, NRR
                     (301) 415-2980
                     E-mail: krn@nrc.gov

                     S. Alexander, NRR          
                     (301) 415-2995
                     E-mail: sda@nrc.gov

                     D. Skeen, NRR  
                     (301) 415-1174
                     E-mail: dls@nrc.gov

Attachments:  
1.  GE Relay Service Advice Letter 516.1
      dated October 25, 1996.                                               
													                            Attachment 1
                                                                             IN 97-12
                                                                             March 24, 1997
                                                                             Page 1 of 3

GE@ MULTILIN GE Power Management
__________________________________________________________________________________
                                                                         General Electric Company
                                                                         205 Great Valley Parkway, Mavern, PA 19355-1337
                                                                         610 251-7000
                                                                



RELAY SERVICE ADVICE LETTER

Subject: HGA Armature Binding                                                   Number 516.1
Issued by: Customer Service                                                        Date: 10/25/96 
Prepared by: Peter A. Kotos


There has been a report of incorrect operation of an HGA17S63 relay (date code: December,
1989). The relay had been continuously energized and failed to provide correct contact operation
when de-energized.  It was reported that the relay armature was not moving freely, it was
mechanically binding at the hinge area.

The relay was returned for examination.  We examined the relay and were not able to reproduce  the
binding condition that was reported.  (The relay was returned disassembled.  When assembled
the relay operated properly electrically and mechanically).

However, a dimensional analysis of the most critical parts indicated that the molded contact 
support was slightly out of tolerance.  Specifically, the assembly hole of the contact support was
slightly off center.

It is conceivable that this offset combined with the manufacturing tolerances of the armature and
magnet frame, possible foreign matter in the hinge area and maybe excessive side pressure applied 
to the contact support when assembled could cause friction between the contact support and 
magnetic frame resulting in armature binding.

According to our Manufacturing Engineering, the mold that produces the contact support was
reworked in 1990 to correct for mold wear and bring the part well within the drawing tolerances
Currently produced contact supports were checked and are well within the drawing tolerances 
and do not produce armature binding.

Based on the field report, it is assumed that some HGA"s may have been shipped with a marginal
condition of armature clearance until this condition was noted by Quality Control and the mold
was corrected..                                                                              Attachment 1
                                                                                             IN 97-12
                                                                                             March 24, 1997
                                                                                             Page 2 of 3

Page 2                    SA #5 16.1                               10/25/96


Although it is not possible to determine exactly when the possible problem began, it is estimated
that relays manufactured between January, 1989, and June, 1991, (Date Codes: ND, OD, PD,
RD, SD, TD, UD, VD, WD, XD, YD, ZD, NE, OE, PE, RE, SE, TE, UE, VE, WE, XE, YE,
ZE, NF, OF, PF, RF, SF, AND TF) are suspect and may be checked for armature binding as
follows:


         1. De-energize the relay, coil and contacts.
         2. Close the armature fully by hand (push armature against the pole, see Fig. 1), and
         gradually release.  For correct position, the armature should move to the fully open
         position with no binding and with correct contact action.  The normally open contacts
         should open and the normally closed contacts should close.  If binding is detected, we
         recommend the following:

For "Nuclear 1E" Applications:  Contact General Electric Nuclear Energy Division
Customer Service Hotline:  1-800-425-8108 and refer to Service Advice No. 516.1.

For "Non-1E" Applications: A replacement contact support is recommended.

Replacement contact supports (Part Number. 006118683PI) are available on a no-charge basis
and should be ordered through your local GE district Sales Office.  Requests for the contact
supports must include:
A. A reference to Service Advice No. 516.1
B. Date codes of the relays for which the replacement contact supports will be used.
Installation of the contact support may be accomplished by following the steps outlined in 
Attachment A.

Replacement contact supports will be available through November 1, 1997.
Labor for installation of the contact support or relay are the responsibility of the purchaser..              
					                                                                                          Attachment 1
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                                                                                                           Page 3 of 3

ATTACHMENT A - SA #516.1

The contact support should be replaced as follows: (Refer to Fig. 1)

1.       Disengage the Control spring from the armature end. (Note the groove location of
         the spring hook on the armature).
2.       Remove the assembly screw with its lockwasher.
3 .      Remove the nameplate and spring housing assembly.
4.       Remove the moving contacts from the contact support and note their location for 
         correct reassembly.
5.       Remove the contact support.
6.       Install the new contact support.  Make sure the armature is seated properly in the
         contact support.
7.       Locate the moving contacts in the contact support.
8.       Install the nameplate and spring housing assembly.
9.       Tighten the assembly screw and lockwasher (16 in-lbs. approx).  Hold contact
         support and spring housing assembly together while tightening assembly screw.
10.      Engage the control spring on the same groove on the armature of the relay.
11.      Operate the armature of the relay by hand to make sure that there is no binding.
12.      Electrically check, and adjust if needed, the pickup of the relay in accordance with
         instructions given in the Instruction Book of the particular relay model number.


HGA RELAY

Fig. 1. (side view)
(Figure 1 of GE SAL not included)


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