United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #: 9604220366

M S D  inc.
700 Orange St.
Darlington, SC 29532
Engineering Department
(803) 393-5421   Fax (803) 393-4123

                                                  April 19, 1996

FAX TO:
U.S.  Nuclear Regulatory Commission 
Operations Center

SUBJECT: Report of discovered defect

Gentlemen;
It has come to our attention that a quantity of Struthers-Dunn type
236ABX135NE time delay relays built in 1983 have incorrect coils in them. 
Specifically, the affected relays contain 39 gauge coils, they should
have 43 gauge.  As a result, the coils consume several times the required
power which is dissipated as heat, and upon prolonged energization may
overheat to the point of self-destruction.  We have one such occurrence
to date.

We believe the defect was caused by person or persons who relied on
memory rather than documentation when building these devices.  They were
intended for use on 125 volt DC circuits; the coils installed are those
normally used on 120 volt AC.  Since the relays would function properly
for brief periods, the defect was obviously overlooked.

To date we have found nine relays as described, all at Georgia Power's
Plant Hatch.  All are date coded 8335, which indicates they were built in
the 35th week of 1983.  We are of the opinion this was the only time this
occurred, but there is no way to prove it.  All indications are the
documentation in effect at the time was, had been, _and still is correct.

Fortunately, these relays' coils are clearly marked, and verification of
correct coil gauge can be accomplished with a visual inspection.  The
markings consist of the basic coil part number which may be either 45769
or 45770, followed by a dash, followed by the wire gauge number. Some
gauges, such as the 43, may be followed by a letter (43 is usually
followed by "C").  On the 45769, the wire code is followed by "X".
Thus, the incorrect coils are marked 45769-39X; a correct coil for this
relay would be marked either 45769-43CX or 45770-43C.  In any case, the
coils are also marked beneath the part number with a four-digit date
code.  We strongly recommend any facility that may have additional
affected product inspect their installations immediately, and to replace
any relays found to have incorrect coils.  Again, believe Plant Hatch has
the only ones, but we cannot be


certain.

Since the assets of Struthers-Dunn were acquired in 1990 by MSD, inc. 
there really is no recourse to be taken.  At MSD, we feel we have
sufficient safeguards in place to prevent occurrences as described above. 
We also stand ready to render whatever advice or assistance you or any
user of these products may require.  If anyone has any question or
problem, they are invited to call. In addition to the numbers above, my
direct phone line is (803) 395-8512.  Please feel free to distribute
copies of this letter as you see fit.

                              Sincerely,

                              Thomas R. Mahaffey
                              Product Engrng.  Mgr.
cc:  J.  Steinback
     D.  Scimeca
     T.  Metzler

GENERAL INFORMATION or OTHER            EVENT NUMBER:  30322

LICENSEE: MSD, INC                      NOTIFICATION DATE: 04/19/96
     CITY: DARLINGTON   REGION: 2       NOTIFICATION TIME: 12:03 [ET]
   COUNTY:               STATE: SC      EVENT DATE:        04/19/96
LICENSE#:            AGREEMENT: Y       EVENT TIME:        00:00[EDT]
DOCKET:                                 LAST UPDATE DATE:  04/19/96

                                             NOTIFICATIONS

NRC NOTIFIED BY: MAHAFFEY               VERN HODGE          NRR 
HQ OPS OFFICER:  BOB STRANSKY

EMERGENCY CLASS: NOT APPLICABLE
10 CFR SECTION:
CDEF 21.21(b)(2)   DEFECTS/NONCOMPLIANCE

                               EVENT TEXT

PART 21 REPORT - INCORRECT COILS INSTALLED IN TIME DELAY RELAYS

THE FOLLOWING IS TEXT EXCERPTED FROM A FACSIMILE SUBMITTED BY THE
VENDOR:

"IT HAS COME TO OUT ATTENTION THAT A QUANTITY OF STRUTHERS-DUNN
TYPE
236ABX135NE TIME DELAY RELAYS BUILT IN 1983 HAVE INCORRECT COILS IN
THEM. 
SPECIFICALLY, THE AFFECTED RELAYS CONTAIN 39 GAUGE COILS; THEY
SHOULD
HAVE 43 GAUGE.  AS A RESULT, THE COILS CONSUME SEVERAL TIMES THE
REQUIRED
POWER WHICH IS DISSIPATED AS HEAT, AND UPON PROLONGED ENERGIZATION
MAY
OVERHEAT TO THE POINT OF SELF-DESTRUCTION.  WE HAVE ONE SUCH
OCCURRENCE
TO DATE.

WE BELIEVE THE DEFECT WAS CAUSED BY PERSON OR PERSONS WHO RELIED
ON
MEMORY RATHER THAN DOCUMENTATION WHEN BUILDING THESE DEVICES. 
THEY WERE
INTENDED FOR USE ON 125 VOLT DC CIRCUITS; THE COILS INSTALLED ARE
THOSE
NORMALLY USED ON 120 VOLT AC.  SINCE THE RELAYS WOULD FUNCTION
PROPERLY
FOR BRIEF PERIODS, THE DEFECT WAS OBVIOUSLY OVERLOOKED.

TO DATE, WE HAVE FOUND NINE RELAYS AS DESCRIBED, ALL AT GEORGIA
POWER'S
PLANT HATCH.  ALL ARE DATE CODED 8335 WHICH INDICATES THEY WERE
BUILT IN
THE 35TH WEEK OF 1983.  WE ARE OF THE OPINION THIS WAS THE ONLY TIME
THIS
OCCURRED, BUT THERE IS NO WAY TO PROVE IT ...  FORTUNATELY, THESE
RELAYS'
COILS ARE CLEARLY MARKED, AND VERIFICATION OF CORRECT COIL GAUGE
CAN BE
ACCOMPLISHED WITH A VISUAL INSPECTION ...  AGAIN, WE BELIEVE PLANT
HATCH
HAS THE ONLY ONES, BUT WE CANNOT BE CERTAIN."

THE ASSETS OF STRUTHERS-DUNN WERE PURCHASED IN 1990 BY MSD, INC.



*** END OF DOCUMENT ***
Page Last Reviewed/Updated Thursday, March 29, 2012