United States Nuclear Regulatory Commission - Protecting People and the Environment


ACCESSION #: 9508020264

                                   ABB

July 19, 1995                                          Page 1

Document Control Desk
US Nuclear Regulatory Commission
Washington, D.C. 20555

SUBJECT:  ABB Relays, Type 51's and 87T
          Defective Tap Block
          (10CFR Part 21 Report)

NOTIFICATION BY:    ABB Power T&D Company
                    Protective Relay Division
                    7036 Snowdrift Road
                    Allentown, PA 18106
                    Harry A Hinch
                    Quality Assurance

The ABB Relays are electronic protective relays used in electrical
switchgear.

The ABB Distribution Relay Division is issuing this Part 21 Report to
advise its customers of a potential problem with type 51's and 87T
relays.  This problem is limited to type 51 relays catalog number series
443/423/223 and type 87T relay catalog number series 419T / 219T
manufactured during the 5/1/94 through 6/15/95 time period.

The potential problem has been identified as a defective Tap Block, ABB
part number 609224-001, this part is a seven (7) position tap block
located on the upper transformer printed circuit board.  This part is
used to change the relay's current settings.

The tap block is designed to revert to the highest tap rating when the
tap pin is removed.  A small percentage (.0025) of these tap blocks were
found to be defective from our supplier, when the tap pin is removed the
tap block will open circuit the transformer circuit.
The transformer circuit is externally wired to the systems Current
Transformers.  When the CT's are open circuited a large voltage potential
is possible creating a potential hazard to the operator.

                      ABB Power T & D Company Inc.

Telephone:               Distribution Relay Division        fax:
610-395-7333             7036 Snowdrift Road, Suite 2       610-395-1055
                              Allentown, PA 18106

July 19, 1995                                               Page 2

The Attachment 1 page identifies the relay types, catalog numbers,
customers, serial numbers, purchase order numbers and sales order numbers
of the relays containing suspect defective Tap Blocks.  ABB Relay
Division Allentown will notify all the end users who purchased these
Relays

ABB recommends that all users identified on the Attachment #1 page verify
by testing per the instruction listed on the enclosed Product Advisory
Letter, PAL 95-108

Prepared by
               Harry Hinch
               QA Supervisor

Reviewed by
               Jack Martin
               Product Line Manager

Reviewed by
               Cheryl Dahle
               Manager, Total Quality

Reviewed by
               Robert Smith
               Site Manager

Enc: Attachment #1
     PAL 95-108

Attachment 1 "Nuclear Services Customer List, Page 1 July 18, 1995"
omitted.

                                   ABB

                                                  PAL 95-108 5/31/95

             Product Advisory Letter-Relay Type 51's and 87T

The ABB Distribution Relay Division is issuing this Product Advisory
Letter (PAL 95 - 108 ) to advise its customers of a potential problem
with type 51's and 87T relays.  This problem is limited to type 51 relays
catalog number series 443/423/223 and type 87T relays catalog number
series 419T/219T manufactured during the 5/1/94 through 6/15/95 time
period.  This Product Advisory Letter will be issued to customers who
have purchased the above type relays that could have this potential
problem.  All units involved are covered under our warranty.

The potential problem has been identified as a defective tap block, ABB
part number 609224-001, this part is a seven (7) position tap block
located on the upper transformer printed circuit board.  This part is
used to select or change the relay's current settings.

The tap block is designed to revert to the highest tap rating when the
tap pin is removed.  A small percentage (.0025) of these tap blocks were
found to be defective from our supplier, when the tap pin is removed the
tap block will open circuit the transformer circuit.
The transformer circuit is externally wired to the systems Current
Transformers.  When the CT's are open circuited a large voltage potential
is possible creating a hazard to the operator.
All suspect relays should be tested or checked during the next scheduled
routine maintenance.

Warning:

Customers should not attempt to change the tap pin location while the
units are energized.  Open circuiting the CT's presents a potential for
serious injury or death.

The relay can be checked after removing it from service by measuring the
impedance at the connection in the rear of the CT board.

On single phase overcurrent units Cat # XXXSXXXX remove the tap pin from
the front of the unit and check for continuity between terminal #3 and
#4.  If continuity is present the tap block is working correctly.  If
there is no continuity notify the factory immediately and do not return
the unit to service.

On three phase overcurrent units Cat #XXXT/PXXXX remove the tap pins from
the front of the unit and check for continuity between terminals #1 and
#2, #3 and #4, and #5 and #6.  If continuity is present the tap block, in
that Phase, is working correctly.  If there is no continuity notify the
factory immediately and do not return the unit to service

On Transformer Differential relays Cat #419T/FXXXX remove the tap pins
from the front of the unit and check for continuity between terminals #1
and #2, #5 and #6, and (#3 and #4, three (3) winding unit only) If
continuity is present the tap block is working correctly.  If there is no
continuity notify the factory immediately and do not return the unit to
service

For those who find defective tap block in their relays and wish to return
their relays to the factory for the component change, please contact the
Repair Department at the Relay Division in Allentown, Pa..  1-800-634-
6005 or 610-395-7333 to make the necessary arrangements.  The component
change will be made at no charge until 6/97.  Questions regarding this
PAL should be directed to Harry Hinch, QA Supervisor, at the above listed
numbers.

                      ABB Power T & D Company Inc.

Telephone:          Distribution Relay Division             fax:
610-395-7333        7036 Snowdrift Road, Suite 2            610-395-1055
                         Allentown, PA 18106

*** END OF DOCUMENT ***

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