ML20072J887
| ML20072J887 | |
| Person / Time | |
|---|---|
| Site: | Zimmer |
| Issue date: | 03/22/1983 |
| From: | Duvall D BBC BROWN BOVERI, INC. (FORMERLY BROWN BOVERI CORP. |
| To: | Stello V NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8303300245 | |
| Download: ML20072J887 (10) | |
Text
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'BBC Brown Boveri eiectric inc BROWN BoVERI Manufacturer of I-T-E Electrical Power Equipment March 22, 1983 36 Mr. Victor Stello, Jr., Director Of fice of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.
20555
Reference:
W. H. Zimmer Nuclear Power Station 10CFR50.55(e) Report Dated February 23, 1983 Brown Boveri Electric Control Device for Medium Voltage Circuit Breakers
Dear Mr. Stello:
On February 23, 1983, the W. H. Zimmer Nuclear Power Station filed an interim 10CFR50.55(e) Report with Region III of the U. S. Nuclear Regulatory identi-fying a potentially reportable deficiency of a broken limit switch carrier on the HK control device used on some Brown Boveri Electric HK circuit breakers.
This particular control device is used on circuit breaker types 7.5KV through 15KV, 500 through 750MVA; 5HK 350, 3000; and all HKV circuit breakers.
The purpose of this report is to furnish the NRC with supplemental information to the report filed by C G & E and clarify the extent of this potential problem at other Nuclear Power plants.
Enclosed is a copy of the BBE Engineering Analysis of the broken limit switch carrier of this HK control device and a copy of the BBE IB-8303 which provides instructions for inspection and corrective action, if required, for the control device.
x Factory Specification records indicate that circuit breakers manufactured between March, 1974 and July, 1978, inclusive, could be subject to this condi-tion.
The date of manufacture for the circuit breaker is stamped on the nameplate which is mounted in the lower front rignt hand corner.
A broken limit switch carrier will probably cause the electrical close to be
- inoperative, but has no effect on the manual closing and electrical or manual tripping of the circuit breaker.
Normally, the main protective function of the circuit breaker is to provide trip function under all conditions but there may be applications where it is s;
important that the circuit breaker be able to close on demand.
8303300245 830322 PDR ADOCK 05000358 s
PDR Switchgear Systems Division Spring House, PA 19477 + (215) 628 7400
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March 22, 1983 Page 2 Enclosed is a list of Nuc'1 car Power Stations for which these circuit breakers were manufactured during the period of March, 1974 through July, 1978. Also, since a dimension "B" has.been added to Figure 2 of the enclosed IB-8303, this information will be' transmitted to all Nuclear Power Stations utilizing these circuit breakers.
The dimension "B" was previously considered _to be a factory check only, however this information will be added to the general Instruction Bulletin, IB 6.2.2.7-1 (8.2.7.4) for'the HK circuit breakers.
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ENCLOSURE TO 3/22/83 LETTER TO VICTOR STELLO, JR. - NRC 4
DETROIT EDISON COMPANY FERMI COMMONWEALTH EDISON LASALLE COUNTf CONSUMERS POWER MIDLAND
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vcx. sw Manufacturer of I-T-E Electrical Power Equipment ANALYSIS OF HK CONTROL DEVICE (LIMIT SWITCH) FAILURE (HK BREAKER TYPES - 7.5KV THRU 15KVe1500 THRU 750 MVA; 5HK350, 3000)
N~LL HKV BREAKERSL
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BACKGROUND
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One defective HK control device, BBC part number 191921-T6, was returned from the Cincinnati Gas and. Electric Co. to the BBC production plant in Columbia, South Carolina for evaluation. The device was returned on BBC RGA B10112, Material Non-conformance Report 101150 dated 2-10-83.
NATURE OF ' FAILURE When the failed device was examined at Columbia, the plastic contact carrier, containing the three limit switch contacts (2-LSb contacts,1-LSa contact),
was found broken.
Re: typical HK wiring diagram 196270 attached. The most common reason for breaking the carrier is due to excessive overtravel of the lever. See IB-8303 attached Fig.1.
This overtravel overdrives the limit switch crank which causes breakage of the carrier. The overtravel of the lever is limited by the lever stop and'as long as the dim "B", Fig. i, is not greater than 1/16 inch, breakage should not occur.
Tests conducted in July.of 1978 have substantiated this.
AFFECT OF FAILURE ON BREAKER OPERATION
' Failure of these contacts can affect the electrical closing function of the breaker, i.e., the closing springs may not charge electrically and if the springs are charged electrically or mechanically, the breaker may not be able to close electrically.
The failure of the limit switch contacts does not affect the manual closing of the breaker and does not affect electrical or manual tripping of the breaker.
j CORRECTIVE ACTION Instruction Bulletin - The dim.
"B", IB-8303 Fig. 2, has always been considered to be a factory check and therefore the Instruction Bulletin has not addressed dim. "B".
However, due to its importance, dim. "B" will be added to the general.
Instruction Bulletin, IB 6.2.2.7-1 (8.2.7.4).
~ Breakers in the field - IB-8303 has been issued for the inspection and/or cor-rection of, breaker in the field for obtaining dim.
"B".
This bulletin also checks 'out and corrects for dim. "A", however dim. "A" has no affect on the overtravel of the contact carrier.
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page 2.
ANALYSIS OF HK CONTROL DEVICE. (LIMIT SWITCH) FAILURE (HK BREAKER TYPES - 7.5KV THRU 15KV, 500 THRU 750 MVA; 5HK350, 3000)
ALL HKV BREAKERS g..
Factory specification' records iiidicate that breakers manufactured between.Na'rch 1974 and. July 1978., inclusive, are subject to exceeding dim."B" limits and therefore should be checked per IB-8303.
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A broken limit switch carrier will probably cause the electrical close to be inoperative but it has no affect on manual closing or electrical or manual tripping.
Corrective action should be taken as outlined above.
v Prepared by:
Approved by:
e D. H. Lewis L. H. Schmidt Date:
L 2 - 8.3 Date:
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INSTRUCTIONS FOR INSPECTING, ADJUSTING AND/OR REPLACEMENT OF PARTS FOR OBTAINING LIMIT SWITCH ADJUSTMENTS ON BROWN BOVERI. 7.5KV THRU 15KV, 500 THRU 750 MVA; 5HK350, 3000; ALL HKV BREAKERS IB-8303 l
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' INSTRUCTIONS FOR INSPECTING, ADJUSTING AND/OR REPLACEMENT
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OF PARTS FOR OBTAINING LIMIT SWITCH ADJUSTMENTS ON BROWN B0 VERI 7.5KV -THRU 15KV,.500 THRU 750 MVA; 5HK350,'.3000; ALL HKV' BREAKERS
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(MANUFACTURED BETWEEN MARCH 1974 AND JULY 1978 INCLUSIVE)
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GENERAL ~
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1.1 For general breaker instruction, refer to the appropriate Brown Boveri Instruction Bulletin.
1.2 The breaker must be removed from the switchboard.
1.3 Unless otherwise stated, the breaker is to remain open with closing springs discharged.
1.4 The reason for a gap at Dim. "A" is to insure the "LSa" contact is made The gap at Dim. "B" is to insure that the "LSb" contacts are made and to limit the overtravel of the lever so that the limit switch plastic carrier inside the control relay is not broken.
1.5 This Instruction Bulletin supersedes IB-7803.
2.
INSP'ECTION AND ADJUSTMENT FOR DIM. "A" (See Fig.1)
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2.1 Charge the closing springs electrically or manually.
2.2 Check Dim. "A" with feeler or pin gages.
2.3 If required, readjust the screw (4) to Dim. "A" after first loosening the jam nut (5) and then retightening the jam nut after the adjustment.
2.4 Close and open the breaker to discharge the closing springs.
3.
INSPECTION AND ADJUSTMENT FOR DIM. "B"(See Fig!s 1 and 2) 3.1 For this procedure, the breaker is to be open and the closing springs discharged.
3.2 Check Dim. "B" with feeler or pin gages. (See Fig. 2) 3.3 If Dim. "B" is not within dimensions, it is necessary to shim the lever stop(7) up or down as required. This is done by adding or removing shims (2) at the lever stop. (See Fig.1) Note that if~ all shims are removed and the Dim."B" still exceeds the max. allowed, the length of the lever stop should be checked.
The lever stops made after July 1978 are 2.17/32 long.. Previous to this, the
.I length was 2 25/32.
If. required, install the shorter lever stop (7).
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Lever stop 193392-A 1
2 17/32 overall length.
Used in breakers built after July 1978.
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