U-602704, Part 21 Rept Re Regulated Power Transformer 1AP75ERT Tripping Several Times.Caused by Addition of Step Load from Low or No Load Condition.Will Disconnect Four Potentially Affected Transformers from Div 2 Electrical Sys

Part 21 Rept Re Regulated Power Transformer 1AP75ERT Tripping Several Times.Caused by Addition of Step Load from Low or No Load Condition.Will Disconnect Four Potentially Affected Transformers from Div 2 Electrical Sys

ML20138Q171
Person / Time
Site:	Clinton
Issue date:	02/27/1997
From:	Connell W ILLINOIS POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-PT21-97 U-602704, NUDOCS 9703060182
Download: ML20138Q171 (3)

Text

_ . _._ _ __. .

lilinois Power Company e Chnton Power Station

, P.O. Box 678

, Chnton. IL 61727 Tel 217 935-5623 ,

Fax 217 935-4632 i

Wilfred Connell I KLMMS v>ce eree>6e"i u 602704 l

P&WER 4F.140 '

WC-123-97 February 27, 1997 4 2 1

J 4

Docket No. 50-461 10CFR21.21 Document Control Desk Nuclear Regulatory Commission  !

Washington, D. C. 20555

Subject:

10CFR21 Final Report 21-97-004: Phoenix Power Systems Regulated Power Transformer Supplied and Qualified by United Controls l International is Not Capable of Operating Over the Required Output Range l I

l

Dear Madam or Sir:

I On January 7,1997, Illinois Power (IP) initiated Condition Report 1-97-01-062 due to regulated power transformer I AP75ERT tripping several times for no known i reason. The transformer was installed under Plant Modification AP-028 to resolve a 1 degraded voltage relay setting condition. The first trip occurred after the modification was released for operations. An investigation of the cause of the trips determined that the transformer tripped off with the addition of step load from a low or no load condition. IP has been advised by the manufacturer that the transformer units require a minimum load of 2 amps per phase to remain stable, contrary to the purchase specification which requires voltage control from the no load condition to unit rating.

The safety-related 120-volt distribution panel fed by the transformer de-energizes when the transformer trips. This issue was identified as potentially reportable under the provisions of10CFR, Part 21.

The regulated power transformer is model number P3C015C6/EAN Guardian Power Conditioner manufactured by Phoenix Power Systems. The transformer was qualified Class lE and supplied to Clinton Power Station by United Controls International.

On the basis that the transformer does not meet the requirements of the procurement document, and the failure of the transformer to perform its function could result in the loss of power to safety-related equipment loads, IP has concluded that this issue is reportable under the provisions of 10CFR, Part 21.

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Page 2 i

IP is providing the following information in accordance with 10CFR21.21(c)(4).

- Initial notification of this matter will be provided by facsimile of this letter to the NRC Operations Center in accordance with 10CFR21.21(c)(3) within two days of the date the i responsible officer signs this letter.  !

4 (i) Wilfred Connell, Vice President ofIP, Clinton Power Station, Post Office Box  !

678, Clinton, Illinois, 61727, is the responsible officer notifying the Nuclear -

. Regulatory Commission of a condition reportable under the provisions of 10CFR, I Part 21.

(ii) The basic component involved in this condition is a dry type regulated power

transformer, Phoenix Power Systems model number P3C015C6/EAN Guardian .

. Power Conditioner, i

(iii) The regulated power transformer was manufactured by Phoenix Power Systems, San Diego, California. The unit was qualified Class IE and supplied to Clinton  !

Power Station by United Controls International, Stone Mountain, Georgia.

(iv) The purchase specification requires voltage control from the no load condition to unit rating. Contrary to this requirement, IP has found that the transformer is not stable in the no load condition and trips when lightly loaded under various plant  ;

conditions. A trip of the transformer upon addition of a safety load could cause ,

the loss ofpower to all the loads fed by that transformer and result in the failure of safety related equipment to perform intended safety functions.

(v) The repeated tripping of the regulated power transformer was identified and determined potentially reportable under the provisions of 10CFR21 on January 7, 1997, 1

(vi) Clinton Power Station (CPS) hb 4 of the potentially affected transformers

]

installed in the Division 2 electrical system under Plant Modification AP-028.  !

Only one of the four units has experienced tripping problems.

I (vii) IP is disconnecting the four potentially affected transformers from the Division 2 electrical system to remove them from service in accordance with Plant i Modification AP-032. IP and representatives of United Controls are working on a ,

network of filters / surge suppressors and minimum load resistors to eliminate the  !

tripping problem.

(viii) IP has no advice about this issue for other purchasers or licensees.

• U-602704 Page 3 Additional information about this issue may be obtained by contacting A. B.

Haumann, Engineering Projects, at (217) 935-8881, extension 4078.

Sincerely yours, f Nd 0wW Wilfred Connell Vice President RSF/krk cc: NRC Clinton Licensing Project Manager NRC Resident Office, V-690 Regional Administrator, Region III, USNRC lilinois Department of Nuclear Safety INPO Records Center United Controls International