Control Copy: =-Entergy

ENT000124 Submitted: March 28, 2012

• =-Entergy ~ucleaz ~ortheast

o

STATION OR ANNUA

Work Order No. ---------'+

~ . Wńt~

Approved By:

Pro

Procedure Use Is:

D Continuous

• Reference

D Information

AUXILIA ERVICE,

/ 5'" '1- 07 Date

Date '

Date

Control Copy:

Effective Date: 5-- /(07-

of 25

RANSFORMER PECTION

M~NTENANCEPROCEDURE

NEW PROCEOURE

STATION OR UNIT AUXILlARY TRANSFORMER ANNUAL IN-SERVICE INSPECTION

REVISION SUMMARY (Page 1 of 1)

1.0 REASON FOR REVISION

NO. O-XFR-407-ELC

of 25

1.1 NEW PROCEDURE developed due to procedure consolidation.

1.2 This procedure supersedes Unit 3 procedure XFR-009-ELC.

2.0 SUMMARY OF CHANGES

2.1 Updated format per IP-SMM-AD-1 04.

2.2 Procedure Validation Requirements.

REV.O

2.2.1 During the first time use of this procedure, the user validation process shall be folIowed for this task. During work peńormance, the user shall compare the procedure against field conditions and document all non-intent change-related discrepancies in Atlachment 5 for future procedure revision input. Ali identified discrepancies shall be evaluated by the responsible technical representative. Follow IP-SMM-AD-1 02 for any identified discrepancies involving procedure intent changes.

STATION OR UNIT AUXILlARY TRANSFORMER NO. O-XFR-407-ELC REV.O

ANNUAL IN-SERVICE INSPECTION of 25

TABlE OF CONTENTS

Seclion Tille Page 1.0 PURPOSE ............................................................................................................ 4

2.0 PRECAUTIONS AND L1MITATIONS .................................................................... 5

3.0 PREREQUISITES ................................................................................................. 6

4.0 PROCEDURE ....................................................................................................... 8

4.1 Recommended Equipment ........................................................................ 8

4.2 Annualln-Service Inspection ..................................................................... 9

4.3 Procedure Complete ................................................................................ 15

5.0 REFERENCES ................................................................................................... 16

6.0 RECORDS AND DOCUMENTATION ................................................................. 17

ATTACHMENT 1

ATTACHMENT 2

ATTACHMENT 3

ATTACHMENT 4

Annual Inspection Data Sheet.. ..................................................... 18

Transformer Outline and Equipment Location ............................... 21

Industry Experiences ..................................................................... 22

I PEC Maintenance Feedback Form .............................................. 25


ANNUAL IN-SERVICE INSPECTION of25

1.0 PURPOSE

1.1 This procedure establishes the requirements for the Annual In-Service Inspection of the Station Auxiliary Transformers and Unit Auxiliary Transformers.

1.2 This procedure can be used at Unit 2 and Unit 3.

1.3 The sections of this procedure required to be performed have been identified by Planning and have been indicated in the Work Order. The Supervisor shall initial those sections below.

X *4.1 Recommended Equipment

___ *4.2 Annualln-Service Inspection

X *4.3 Procedure Complete

Steps within sections indicated by an asterisk "*,, may be peńormed concurrently or in any sequence at the discretion of the Maintenance Supervisor.

1.4 Description of Component:: _______________ _



2.0 PRECAUTIONS AND LlMITATIONS

2.1 Follow EN-IS-1 01, Industrial Safety and Health Program and EN-IS-111, Generallndustrial Requirements and any ather applicable Industrial Safety Procedures.

2.2 Follow IP-SMM-MA-118, Foreign Material Exclusion while performing maintenance activities. Cover all openings wit h appropriate covers when work is not in progress.

2.3 This procedure requires the use of Maintenance Standard 0-MS-205 (Documenting Work Performed). Maintenance personnel involved in these activities must be familiar wit h the Standard.

2.4 Verify proper equipment grounding as specified on your Work Clearance.

2.5 The transformers are energized. Take extra precautions while performing this inspection

2.6 Follow EN-IS-123, Electrical Safety, for wark on or near (within limited approach) exposed energized equipment.

2.7 Electrical Safety Program and Electrical Safety Practices shall be abserved when working on energized equipment as per IP-SMM-IS-1 03 and IP-SMM-IS-104.

Mechanic/Date

Mechanic/Date

Maintenance Supervisor/Date

STATION OR UNIT AUXILlARY TRANSFORMER NO. O-XFR-407 -ELC REV. O


3.0 PREREQUISITES

3.1 Equipment Tagout No. _______________ _ ENSURE tags are hung and verified.

3.2 Notify Rad iation Protection (Rad Pro) prior to the start of work in the Radiologically Controlled Area (RCA).

3.2.1 Comply wit h requirements and instruction of Radiation Work Permit (RWP) # _______ _

3.3 COORDINATE wit h Waste Management (WM) for disposal of any waste generated during this maintenance activity.

3.4 Maintenance procedure verified to be the latest approved revision, any inclusive DRNs verified to be attached as per IP-SMM-AD-1 02.

3.5 Read through Attachment 3, Industry Experiences, prior to the start of work.

3.6 Unless otherwise noted, steps marked with a double initial block, SHALL be verified by Maintenance per step criteria.

3.7 ENSURE ONL y approved parts, drawn against this Work Order, are used for this task. Return ALL unused material to be credited back into stock.

3.8 IF any unacceptable inspection resuJts are found in this procedure, THEN contact Maintenance Supervisor/Responsible Engineer for resolution. Record WO/CR# for any significant as found conditions in the procedure complete section.

3.9 ENSURE personnel performing signoffs during the performance of this procedure, are listed in the Procedure Complete section of this procedure.

3.10 Establish a clean work area per IP-SMM-MA-1 06 and IP-SMM-MA-118 prior to the start of work.

3.11 Document any required actions that cannot be accomplished within scope of this procedure by initiating a WRT. Record WRT numbers initiated and any corrective actions taken during test in comments section of Attachment 1 .

STATION OR UNIT AUXILlARY TRANSFORMER NO. O-XFR-407-ELC REV. O


3.12 Oualified Inspection Personnel shall be notified prior to start of work for all activities performed by Supplemental l Contractor personnel. Addition of Inspection Hold Points will be added where appropriate.

!E Entergy personnel perform work activity, THEN N/A this step.

N/A I_I Maintenance Supervisor/Date

Hold Points Added: YES I_I NO I_I Oualified Inspector/Date

3.13 PRE-JOB BRIEF was discussed in accordance with IP-SMM-HU-102 (Pre-job Briefing and Post Job Critiques).

3.14 Ali prerequisites have been completed.

Mechanic/Date

Mechanic/Date




4.0 PROCEDURE

4.1 Recommended Eguipment

4.1.1 Test Equipment

• Thermometer ( C)

• Portable, Relative Humidity Reading Device

4.1.2 Special Tools

• Binoculars (minimum 7x 35 power)

• Torque wrenches (capable of 75 ft-Ibs.)

4.1.3 Supplies

• Clean lint-free cloths

• Disposable Surgical Gloves or Equivalent Type Glove

STATION OR UNIT AUXILlARY TRANSFORMER NO. O·XFR·407·ELC REV.O


4.2 Annual In-Service Inspection

NOTE

1. Subsections of this procedure are peńormed independent of each other as directed by the Work Request.

2. Maintenance Supervisor shall be notified of unsatisfactory inspection or test results.

3. Readings, inspection results, etc. obtained in Section shall be recorded/indicated on Attachment 1, Annual Inspection Data Sheet.

4. Temperature readings will be recorded/indicated in oC and pressure reading in PSIG.

5. Refer to Atłachment 2 for component identification.

4.2.1 NOTIFY the Control Room Supervisor (CS) of inspection activity. mech

4.2.2 CONTACT Chemistry Oepartment to take a sample of transformer mech oil in accordance wit h their procedure applicable procedure.

Chemistry Oepartment Notified: YES I_I NO I_I

4.2.3 RECORD ambient air temperature. mech

Ambient Air Temperature: oC

4.2.4 RECORD transformer oil temperature (from oil temperature mech gauge).

Oil Temperature: oC

4.2.5 RECORD transformer winding temperatures from the wind ing mech temperature gauges.

Winding Temperature: oC

STATION OR UNIT AUXILlARY TRANSFORMER NO. 0-XFR-407-ELC REV.O


4.2.6

4.2.7

4.2.8

4.2.9

4.2.10

4.2.11

COMPARE the ambient temperature reading take in Step 4.2.3 wit h oil temperature reading taken in Step 4.2.4 AND VERIFY that the oil temperature is greater than the ambient temperature.

YES I_I NO I_I

Visualfy INSPECT transformer exterior (radiators, pumps, gasket etc.) for physical damage andlor oilleaks. EXAMINE closely for damage occurring as a result of enviranmental conditions, radents, bird nesting, aR any other conditions which might interfere wit h normai operation.

CORRECT any deficiencies. IF NOT able to correct any deficiencies, THEN IDENTIFY location AND RECORD in detail in Atlachment 1. ISSUE WRT tags for alf deficiencies NOT repaired via this WR.

CHECK 138kv bush ing oillevels (should be visible in transparent section of bushing) AND RECORD results (Station Auxiliary Transformer oniy).

CHECK transformer oillevel (from oil level gauge - location of gauges is indicated on Atlachment 2) AND RECORD results.

• IF indication is between HIGH AND LaW, THEN oillevel is satisfactory (ACC).

RECORD reading fram transformer pressure gauge (pressure should read fram 0.5 to 3.0 psi maximum)).

4.2.12 CHECK Nitragen Gas Control Cabinet for condensed oil vapor as follows:

4.2.12.1 CLOSE transformer feeder valve.

STATION OR UNIT AUXILlARY TRANSFORMER NO. O-XFR-407 -ELC REV.O

ANNUAL IN-SERVICE INSPECTION ot 25

4.2.12.2 OPEN sump drain valve.

4.2.12.3 WHEN only nitrogen gas is being expelled from valve, mech THEN CLOSE sump drain valve.

4.2.12.4 Slowly OPEN transformer feeder valve to admit gas to mech transformer.

4.2.12.5 MONITOR transformer pressure gauge for reading mech between 0.5 psi and 3.0 psi maximum.

4.2.12.6 INDICATE "YES" on Inspection Data Sheet for Oil mech Vapor Check.

4.2.12.7 RECORD results on Inspection Data Sheet.

NOTE

Location of fans, pumps, and flow gauge is indicated on Attachment 2.

4.2.13 RECORD if both fan banks are on or off.

ON I_I OFF I_I

4.2.14 RECORD if bot h oi! pumps are on or off.

YES I_I NO I_I

4.2.15 RECORD if oi! flow is indicated on flow gauge(s).

YES I_I NO '_I

-



NOTE

Oil Pump operation is indicated via mounted gauges. Fans/pump operate in Group 1 and/or Group 2.

4.2.16 CHECK that bot h bank fans/pumps in operating group are running. IF both fans/pumps in operating group are NOT running, THEN CONTACT Operations to operate the non operating group to verify the operability.

NOTE

Transformer yard is NOT to be used as a storage area for tools or equipment.

4.2.17 INSPECT transformer yard for the following as a minimum: mech

• Debris, rodents, bird nesting, etc.

• Unauthorized equipment or vehicles.

• Any condition that may present a safety hazard to personnel or equipment.

mech 4.2.17.1 DOCUMENT any undesirable conditions in Remarks.

4.2.17.2 RESOLVE undesirable conditions or initiate a WRT as mech applicable.

4.2.18 CHECK oillevel in tap changer compartment and selector switch mech compartment from respective oil level gauge.

4.2.18.1 RECORD oil level in transfer switch compartment in mech AUachment 1 .

4.2.18.2 RECORD oil level in selector switch compartment in mech AUachment 1 .



4.2.19

4.2.20

4.2.21

NOTIFY Maintenance Supervisar ar Responsible Engineer of any unacceptable items AND RECORD corrective action taken:

YES I_I NO I_I


Visually INSPECT 138KV bushings on Station Aux Transformer for the following:

• Dust or dirt accumulation

• Obvious chips or cracks

• Any possible heat or corona damage

• Any oil leaks

Visually INSPECT 138KV arrestor on Station Aux Transformer for the following:

• Dust or dirt accumulation

• Obvious chips or cracks

• Possible heat or corona damage

4.2.22 OPEN AND INSPECT control cabinet, gas cabinet and load tap changer control cabinet to verify the following:

4.2.22.1 Strip heaters working.

4.2.22.2 Lights AND receptacles working.

4.2.22.3 No sign of corrosion, water, OR oil in the cabinet.

4.2.22.4 INSPECT for loose, missing, OR broken hardware.

4.2.22.5 INSPECT all gas tubing.

ACC. I_I UNACC. I_I



4.2.23 ENSURE the following are removed from each transformer yard: mech

• Tools

• Cleaning Cloths

• Other Material

4.2.24 INSPECT/CLEAN heat exchangers (radiators) as follows:

4.2.24.1 INSPECT heat exchangers (radiators) for damage OR mech oilleaks.

4.2.24.2 IF any accumulated debris has formed, THEN CLEAN mech the cooling surfaces by using forced air.

4.2.25 NOTIFY Shift Supervisor that inspection is complete. mech

STATION OR UNIT AUXILlARY TRANSFORMER NO. O-XFR-407 -ELC


4.3 Procedure Complete

4.3.1 The Maintenance Supervisor shall record any known CRs generated during and against this maintenance activity.

List of written CRs:

REV. O

--------------------------------

Maintenance Supervisor/Oate

4.3.2 The personnel listed below have performed signoffs in this procedure:

Print Name (First, Last)

Signature Initials

4.3.3 Procedure complete; Acceptance Criteria, if applicable, has been met.

Maintenance Supervisor/Oate



5.0 REFERENCES 5.1 Commitment Documents

5.1.1 None

5.2 Development Documents

5.2.1 Westinghouse Instruction Manual, Type SL core Form Substation Transformer With Type URT Load Tap Changer, I.B. RHR-6940 (WE-125)

5.2.2 WE-46, Type SL Core Form Substation Transformer

5.2.3 49CFR172.1 01, Hazardous Materials Table Special provisions, Hazardous Materials Communications, Emergency Response Information, Training Requirements, Subpart B, Table of Hazardous Materials and Special Provisions.

5.2.4 No. 70B, Electrical Equipment Maintenance

5.2.5 Standards for Maintenance of Power Apparatus (10/94).

5.2.6 ACT #01 ~57819, Maintenance Feedback Form 2001-56.

5.2. 7 XFR-009~ELC, Station or Unit Auxiliary Transformer Annual InService I nspection

5.3 Inteńace Documents

5.3.1 IP-SMM-IS-103, Electrical Safety

5.3.2 IP-SMM-IS-104, Electrical Safety Program

5.3.3 IP-SMM-MA-106, Housekeeping Policy

5.3.4 IP-SMM-MA-118, Foreign Materiał Exclusion

5.3.5 IP-SMM-IS-123,

5.3.6 EN-IS-101, Industrial Safety and Health Program

5.3.7 EN-IS-111, Generallndustrial Safety Requirements

STATION OR UNIT AUXILlARYTRANSFORMER NO. O-XFR-407-ELC REV.O


6.0 RECOROS ANOOOCUMENTATION

6.1 Records

The following required records are generated by this procedure and SHALL be maintained in accordance with Records Retention Schedule:

6.1.1 Complete O-XFR-407-ELC Procedure and associated forms are a part of the Maintenance Work Package.

6.2 Documentation

The following documentation resulting from this procedure are NOT required to be controlled and maintained in accordance with the Records Retention Sched ule:

None

STATION OR UNIT AUXILlARY TRANSFORMER NO. O-XFR-407 -ELe REV. o ANNUAL IN-SERVICE INSPECTION of 25

ATTACHMENT 1 ANNUAL INSPECTION DATA SHEET

(Page 1 of 3)

Annual Inspection Data Sheet COMPONENTS WR No. ---------------------

STEP PARAM ETER UNIT AUX STAAUX ACTION/LIMIT 4.2.3 Ambient Air Temperature oc oc Record reading 4.2.4 Transformer Oil Temperature , oc oc Record reading 4.2.5 'Winding Temperature 1 oc oc Record reading 4.2.6 Oil Temperature greater than Ambient YES NO YES NO Circle One 4.2.7 Exterior Inspection ACC UNACC ACC UNACC Circle One 4.2.9 i Bushing Oil Level ACC UNACC ACC UNACC Circle One 4.2.10 Transformer Oil Level ACC UNACC ACC UNACC Circle One 4.2.11 Transformer Gas Pressure psi psi 0.5 - 7.5 psi 4.2.12 Vapor Found YES I NO I N/A YES l NO l N/A Circle One 4.2.13 Fans Operating ON OFF ON OFF Circle One 4.2.14 Pumps Operating I ON OFF ON OFF Circle One 4.2.15 Flow Indicated YES NO YES NO Circle One 4.2.16 Fan/Pumps Inspection ACC UNACC ACC UNACC Circle One 4.2.17 Yard Inspection ACC UNACC· ACC UNACC Circle One 4.2.18.1 Tap Chan~er Compartment Oil Level ACC UNACC ACC UNACC Circle One 4.2.18.2 : Selector Switch Compartment Oil ACC IUNACC ACC UNACC Circle One

Level 4.2.20 138KV Bushing Inspections N/A ACC UNACC Circle One 4.2.21 138KV Lightening Arrestors N/A ACC UNACC Circle One 4.2.22 Contra I Cabinet Inspection ACC UNACC ACC IUNACC Circle One 4.2.23 Ensure yard is clean YES NO YES NO Circle One 4.2.24.1 Inspection of Heat Exchanger ACC UNACC ACC !UNACC Circle One 4.2.24.2 Clean by forced alr YES NO YES NO i Circle One 4.2.25 Notified Shift Supervisor YES NO YES NO Circle One I nspected by: Init/Date


ANNUAL IN-SERVICE INSPECTION ot 25

ATTACHMENT 1 ANNUAL INSPECTION DATA SHEET

(Page 2 of 3)

COMPONENTS ____________ __ WR No. _________ _

4.1.2. Record results of inspection (as found condition):

Sketch a diagram in the frame below of inspection points wit h damage or potential damage locations identified.

Comments:

Mechanic/Date

STATION OR UNIT AUXILlARY TRANSFORMER NO. 0-XFR-407-ELC REV.O


ATT ACHMENT 1 ANNUAL INSPECTION DATA SHEET

(Page 3 ot 3)

WRNo. COMPONENTS ______________ _ --------------------Ali personnel who perform portions ot this procedure shall print name, sig n initials, and date below.

Prinłed Name Signałure Init/Dałe

Acceptance Verification Note all corrective actions performed and record WRTs in Remarks Section. (Add additional sheets, it required)

Remarks:


Responsible Engineer review and approval.

Ensure procedure has been properly completed.

Ensure WRTs were written, as required, and WRT numbers recorded.

Responsible Eningeer/Date



ATTACHMENT 2 TRANSFORMER OUTLINE AND EQUIPMENT LOCATION

FAULT PRESSU----, RELAY

Oll lEVEl

"-,,"",,-,,,-"E

JUNCTION BOX

(Page 1 of 1)

COOllNG SECTION

6·COOllNG FANS

SUPPlY GAS

I"'-+--ł- PRESSURE GAUGE

FROM NITROGEN CYLINDER lOCATED IN TU RB. BlDG. BEHIND 6.9KV SWITCHGEAR ElV.15'·0"

Oll SAMPlE NITROGEN GAS VALVE CONTROl CABINET

Oll FlOW

GAUGE

Oll PUMP



ATTACHMENT 3 INDUSTRY EXPERIENCES

(Page 1 of 3)

NOTE

This Attachment shall be used to add Industry Experiences as they occur or are found.

1) Cracked Connection Block on Station Auxiliary Transformer

On June 13, 1998, with Braidwood Units 1 and 2 at fuli power, a routine maintenance inspection revealed a crack in the connection block (Delta Uni-bus Corp., Type SBT block connector for 4-inch maximum stud) between the flexible link and low voltage bushing on station auxiliary transformer (SAT) 242-2. The connector is fabricated of two half shelIs that clamp around the insulator-to-conductor connection and is tightened using four corner bolts. Cracking was noted at the mid-span of the connector and some material flaws were also noted. By design, the two halves of the connector do not contact when installed, and a bending stress is exerted over the mid-span of each half when the bolts are tightened. However, the connector face is silver coated to improve conductivity, which minimizes the potential for complete loss of surface contact. A new replacement connector will be machined from a solid block of wrought copper. This event was attributed to equipment design. The original connector was fabricated from sand-cast copper and may have been defective as manufactured. This event is not significant. The problem was discovered during routine maintenance.

2) Loss Of Off-Site Power To The Station Auxiliary Transformer On January 26, 1994, oft-site power source to the Indian Point 2 auxiliary transformer was lost due to a phase to ground fault. This fault deenergized two of six 6.9 Kv buses resulting in the loss of two circulating water pumps and the subsequent slight reduction in vacuum, and a load reduction of approximately 60 MWe. The emergency power sources auto-started and the two buses were reenergized enabling restoration of necessary equipment. An alternate feed of oft-site power was established, lo ad on the two buses was transferred ba ck to oft-site power, and the diesels were secured.

3) Cracked Transformer Insulators On May 23, 1995, the station reported that during an outage on the station auxiliary transformer, the support insulators for the 6.9 kV and 4 kV grounding resistor boxes were cracked. The resistor assemblies dissipate energy from any transformer case-to-ground fault currents that may occur. The cracks were noted to be on the outside of the insulator, on the porcelain materia\. Further inspection revealed that several insulators were broken. The most likely cause is atiributed to moisture entering between the porcelain and steel insert and then freezing.

STATION OR UNIT AUXILlARYTRANSFORMER NO. O-XFR-407 -ELC REV.O


ATTACHMENT 3 INDUSTRY EXPERIENCES

(Page 2 of 3)

4) OE7868 - U-1 System Auxiliary Transformers (SAT's) isolated due to a phase a and Phase B Current Oifferential

ABSTRACT:

On 5/23/96 at 08:04 U-1 System Auxiliary Transformers (SAT's) isolated due to a Phase A and Phase B Current Differential. This de-energized ali 4 kv and 6.9 kv buses on Unit 1. Both 1A and 1 B Diesel Generators auto started and loaded on to Bus 141 and 142.

Non-ESF Buses 143 and 144 both remained de-energized. The previously running Non-Essential Service Water (WS) pumps and Station Air Compressors (SAC's) were powered from Buses 143/144 (Non-ES F equipment buses). (The Unit 2 WS Pump was out of service for a major overhaul.) Without WS pumps (Non-Essential cooling water is a unit common system), Unit 2 did not have cooling water to many loads including Generator Auxiliaries, SAC's, Feedwater/Condensate Pumps, etc. Because there was no cooling to secondary systems, the Unit 2 Reactor was manually tripped at approximately 08:06. Unit 2 responded normally from a manual Reactor trip with the exception of Source Range N-31 failing to indicate and some secondary problems.

EVENT DESCRIPTION:

Yard breakers OCB 5-6 and ACB 6-7 feed the Unit 1 SAT. The Unit 1 SAT consists oftwo transformers 142-1 and 142-2. Each provides a 4 kv and 6.9 kv feed to Unit 1. These feeds are further subdivided inside the Auxiliary Building (AB) into two 4 kv buses

(one SR and one NSR) and two 6.9 kv buses (one of which is usually powered from the Unit Auxiliary Transformer). The buses coming from each SAT transformer into the AB are run in 2 non-segregated bus ducts, one for the 4 kv and one for the 6.9 kv. The 3 phases of 4 kv are all in the same duet (non-segregated), separated from each other by about 4 inches, supported from the top of the bus duet by insulators. The 6.9 kv bus is similar.

The Unit 1 SAT 142-2 underwent a phase to ground short at the middle insulator (at the 14th duet cover, or about halfway between the SAT and the Auxiliary Building). Upon flashing, the arc perpetuated down the bus bar, increasing in breadth until it involved the other phases. The specific evidence which supports this conclusion is: Insulator damage; Water was found still dripping through the bus duet on to the insulator (several hours after the last rain shower); Initial point of arcing was at this insulator and subsequent splatter of bus material could be folIowed from this point. As the arc heated the air and water in the duet, the duet pressurized which caused the bottom paneis to bulge until the pressure was relieved through smali vent holes in the bottom paneis of the duet. The bus ducts were manufactured by H K Porter/Delta Unibus.


ANNUAL IN-SERVICE INSPECTION of25

ATTACHMENT3 INDUSTRY EXPERIENCES

(Page 3 of 3)

CAUSE(S):

The primary reason for the event was chronic water leakage through the insulator mounting holes. This lead to the failure of the bus through one of two mechanisms;

1) A layer of condueting contaminants on this insulator and bus was built up over time.

2) The water caused the degradation of the insulator metal inserts and insulator material between these inserts.

In either case, eventually the current flashed to ground (the duet is grounded) and initiated the event. The specific mechanism of insulator failure is still under investigation.

The cause of the water leakage has two components:

1) There is a weld axially down the center of the top of the duet, that the center insulator mounting bolts must straddle. This did not allow the channel-to-duct seal to be compressed properly.

2) The caulk put on the channel-to-duct interface to supplement sealing this barrier is very thin in the area of leakage on this insulator. There are two other contributing factors that make this specific insulator more susceptible to leakage;

1) The ductwork next to the thin caulk slopes toward the channel directing the water into the caulk.

2) The duet above this duet directs run-off water onto this area.

CORRECTIVE ACTION:

The damage is easily repairable and this event will have no impact on future bus performance once the duet is repaired, the damaged insulators replaced, and the leakage stopped.

Based on the initial findings from this event, the other energized ducts were remotely spot checked on 5/27/96 for ad



ATTACHMENT 4 IPEC MAINTENANCE FEEDBACK FORM

(Page 1 of 1) Fili out all the shaded boxes. If it is a request for a new procedure, insert "new procedure" in the b k' f th d t b A I t b d ox as Ing or e ocumen num er. n e ec ronlC verslon may e use .

IPEC MAINTENANCE DOCUMENT FEEDBACK FORM

TO: PRIORITY:

DATE: 1. HIGH () Procedure Sponsor/Location 2. MEDIUM ()

FROM: EXTENSION: 3. LOW() Originator/ Dept LOG NUMBER:

The following discrepancy was found with

Document Number

Revision , during: Outage Related

No ()

Enter peRS No. CTS No. MOD No., or other source information Yes () Discrepancy:

I propose the following resolution:

CC; Supervisor (ATTACH ADDITIONAL SHEETS OR ACTUAL DOCUMENT IF NECESSARY)

TO: DATE: FROM:

Your information has been received, and will be incorporated. O Yes O No

O Next Revision O Immediately O Other

( ) as you proposed ( ) as described

**REASON/COMMENTS: I I ENGINEER COMMENTS: I

Original: Procedure File I CC; Originator Thanks! We appreciate your feedback!

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