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Subject: Megger Testing of Busses, MCCs, and Distribution Panels
Revision Number and Date: R 0 1/17/2011 / Procedure No.: LUM-FFA-MNT-0016
Use:Reference

Effective Date: TBD

Prepared by:Jerry WayneDate: ______

Reviewed by: Gwen Holladay______Date: ____1/25/11______

Approved by: ______Date: ______

Required review frequency: TBD

Table of Contents

1.Purpose and Scope

2.Acceptance Criteria

3.Special Tools and Materials

3.1Tools

3.2Materials

4.Precautions, Limitations, and Notes

4.1Precautions

4.2Limitations

4.3Notes

5.Prerequisites

5.1Planner

5.2Electricians

6.Definitions and Acronyms

7.Instructions

7.1Busses / Motor Control Centers / Distribution Panels

7.2Loads

8.References

8.1Development References

8.2Performance References

9.Attachments

Attachment A:Megger Test Data Sheet

List of Tables

Table 1: Signature Box

Table 2: Test Voltages

Reviews

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Internal Review

Stakeholder Review

1.Purposeand Scope

The purpose of this procedure is to provide instructions for performing insulationresistance (megger) testing of busses, motor control centers (MCCs), and distribution panels.This procedure provides the minimum guidelines and acceptance criteria necessary toensure that you perform meggering is performed ina safely and consistently manner.

2.Acceptance Criteria

The following acceptance criteria must be met to complete the procedure.

The minimum acceptable value for insulation resistance (R min.) in megohms betweenphase-to-phase (busses and feeder cables) and phase-to-ground should equal or exceedone of the following values:

  • R min. should be equal to or greater than one megohm per KV of rated voltage ofequipment plus one megohm.
  • The the minimum value specified by the equipment manufacturer if different fromabove,[D1] as specified on the applicable Work Order.

3.Special Tools and Materials

Use the following special tools and materials to perform this procedure.

3.1Tools

The following special tools are required:

  • Statascope Statoscope (hot stick) [D2](as required)
  • Ground stick (as required)
  • Ground straps/jumpers
  • Class II Rrubber insulated gloves (600V or greater) with leather protectors
  • Fire retardant coveralls
  • Voltmeter
  • Continuity checker
  • Megger

3.2Materials

The following special tools materials are required:

  • None

4.Precautions, Limitations, and Notes

Before performing the procedure, ensure you understand the following precautions, limitations, and notes.

4.1Precautions

The following precautions shall be followed:

  • To ensure the safety of personnel and accuracy of the test, Gground the test specimen to discharge theaccumulated charges after application ofapplying[D3] megger potential., for the safety of personnel, as well as for test accuracy.
  • Grounding should be the test specimen for four times the amount of time you applied the test voltage was applied.
  • Observe electrical safety precautions to prevent personnel injuries orcomponent damage when working on energized equipment.
  • Ensure that designedprotection features are not defeated during performance of the work.[D4]
  • Wear Class II rubber gloves and fire retardant coveralls whenmeggering at 1001 volts or greater, including when connecting and disconnectingmeggering equipment.
  • Connect ground lead first, and then HV lead. Disconnect ground lead last.
  • Ensure thatUse a good[D5] connection to earth ground is used for both meggering anddischarge of equipment under test.
  • Warn and keep other personnel away from equipment during insulation testing and acapacitance discharge. Utilize safety barriers and flagging when appropriate.
  • Do not perform insulation test in a flammable or explosive atmosphere.

4.2Limitations

None

4.3Notes

The following information may be used while performing the procedure:

  • Do not record readings within thebody of this procedure if you are meggering is being performed to obtain "InformationOnly" type data, as in case of [D6]trouble shooting.
  • Do not record readings hereif you are meggering is being performed as part of another approvedprocedure.
  • Report discrepancies or unsatisfactory results to the Work GroupSupervisor for follow-up actions.Recordproblems found in the"Remarks" section of work package[D7].
  • Read the analog megger on the scale giving[D8] best resolution, and record[D9].Use specific measurements rather than descriptions such as "greater than" or "less than." should not be used. Do not take mMegger readings should not be taken while the pointer or display is pegged (unless onthe highest available range), erratic, or in transit.
  • Record the actual value displayed value on the digital megger,except that theword "Infinity", "INF" or the infinity symbol should be used when the display showsthe digit "1" in the first (left hand) position with the other positions blank.[D10]
  • If an MCC drawout unit is removed[D11], ensure the following:
  • Visually inspect all contacts after the bucket has been slid into MCC,tightened down, and seated against the back of the cubicle.
  • Check all draw out contacts for continuity which that have external power cables connected for continuity. Theyshould be[D12] less than 10 ohms resistance.
  • Inspectbreaker stabs for signs of overheating by looking for discoloration orsigns of arcing.

5.Prerequisites

The following prerequisites must be met before performing this procedure.

5.1Planner

The planner must enter the following information:[D13]

  • Work Order No.: ______
  • Component Tag No.: ______
  • Unit No.:______
  • Serial No.:______

5.2Electricians

Personnel performing this procedure shall review all instructions, and safety requirements prior to performing this procedure.

  • Each personAfter performing work using this procedure,is required to record their your name in the following signature box (see Table 1: Signature Box).If you do not have an RACF ID is unavailable, include your the contact information of the individual.

In the table below,print name, sign name, and initials of the individuals performing this procedure.

Print Name / Sign Name / Initials / RACF ID

Table 1: Signature Box

Enter following information on Attachment A:Megger Test Data Sheet:.

  • Equipment Rated Voltage
  • Test Voltage
  • M&TE numbers and Calibration Due Dates

6.Definitions and Acronyms

CR (from bottom of page 9)[D14]

Live-Dead-Live (L-D-L)

Motor Control Centers (MCCs)

7.Instructions

The procedures below contain instructions for the following tasks:

  • Busses /MCCs Motor Control Centers / Distribution Panels
  • Loads

7.1Busses / Motor Control Centers/ Distribution Panels

Note 1Use this section to perform megger testing of load center busswork that hasbeen isolated from all of its respective loads. Refer to Section 7.2 for megger testingof individual loads.

  1. Ensure Switch power supply breaker to is in "Open" or "Off" position.
  2. Use L-D-L method to de-energize Ensure load side connections of power supply breaker are de-energized byelectrical measurements. Use L-D-L method.
  3. Isolate Ensure all loads associated with buss to be tested. have been isolated.
  4. Disconnecthigh high-voltage sensitive devices and potential transformersfrom buss to be tested.
  5. Record and verify leads lifted, and fuses removed on Verification Sheet[D15]. Verify that information is correct, and have a Use second person man as verifyier the information.
  6. Use table below for appropriate Test Voltages.

Bus Voltage / Test Voltage DC
480 / 500
2500 / 2500
4160 / 5000
6900 / 5000
13800 / 10000

the information is correct. ms?ine. "Hot sticks" seems to be more commonly used. 1111111111111111111111111111111111111111111111
CCs he following signature box 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111Table 2: Test Voltages

  1. Megger busswork phase-to-phase then phase-to-ground for one minute[D16], until readings are stable, or until acceptance criteria is reached.
  2. Record readings on Attachment A: Megger Test Data Sheetthe Data Sheet.
  3. Ground and discharge each phase tested.
  4. Compare readings taken with the acceptance criteria given in Section 2.
  5. Remove all test leads and grounding devices. Record on Attachment A: Megger Test Data SheetMegger Test Data Sheet.
  6. Connect high voltage sensitive devices, and potential transformers.
  7. Record and verify leads landed and fuses installed on Attachment A: Megger Test Data SheetVerification Sheet. Have a Use second personmanas verify the informationier.
  8. Perform a post work close-out inspection to ensure that all tools and foreign material have been removed.

7.2Loads

Note 2Megger testing is only required for power circuits. Megger testinginstrument and control circuits is not required, or desirable.

  1. Use applicable electrical drawings to determine what loads to megger test.
  1. Record tag numbers and test connections for each load to be meggered onAttachment A:Megger Test Data Sheet.
  2. Ensure Switch circuit breaker for each load tois in "Open" or "Off" position.
  3. Use L-D-L method to de-energize Ensure load side connections of each breaker are de-energized byelectrical measurements. Use L-D-L method.
  4. For motors only, perform phase-to-phase continuity checks[D17]between eachphase andrecord "Sat" or "Unsat" on Attachment A:Megger Test Data Sheet.

Note 3Phase-to-phase megger readings are only required for feeder cables toother MCCs or distribution panels. The breaker on the opposite end of the feeder cablemust be open to obtain satisfactory readings.

  1. Meggereach load phase-to-ground and,only if required, phase-to-phase for each load for approximately one minute or until acceptance criteria is reached.
  2. Ground and discharge each load tested.
  3. Remove all test leads and grounding devices. Record[D18]on Attachment A:Megger Test Data Sheet.
  4. Review all readings taken and determine if they meet acceptance criteria as given in Section 2.
  5. Contact your supervisor and report any equipment deficiencies. Write a CR for repair or evaluation of the equipment.

8.References

Development references are documents used to develop the procedure. Performance references are documents referenced within the procedure.

8.1Development References

[1]IEEE Std 43-2000 Recommended Practice for Testing Insulation Resistance of Rotating Machinery

[2]IEEE Std 62-1974 Guide for Field Testing Power Apparatus Insulation

8.2Performance References

[1]Generation Safety Handbook[D19]

[2]LUM-FFA-REL-0014 Standard of Human Performance Improvement (LUM-FFA-REL-0014)

[3]LUM-FFA-SAF-0002 Hazardous Energy Control Program: LOTOV-Lockout/Tagout /Verify

[4](MSDS) Material Safety Data Sheet (MSDS)

9.Attachments

The following attachments are appended to this procedure.

Attachment A:Megger Test Data Sheet

Attachment A:
Megger Test Data Sheet

5.2Equipment Rated Voltage: ______VACTest Voltage: ______VDC

7.1Busses / Motor Control CentersMCCs / Distribution Panels

Equipment Tag Number: ______

A-B ______MegohmsB-C ______MegohmsC-A ______Megohms

A-G ______MegohmsB-G ______MegohmsC-G ______Megohms

======

Equipment Tag Number: ______

A-B ______MegohmsB-C ______MegohmsC-A ______Megohms

A-G ______MegohmsB-G ______MegohmsC-G ______Megohms

======

Equipment Tag Number: ______

A-B ______MegohmsB-C ______MegohmsC-A ______Megohms

A-G ______MegohmsB-G ______MegohmsC-G ______Megohms

Acceptance Criteria: Equal to or greater than one megohms per KV of rated voltage in step 5.2 plus one megohm, or as specified on Work Order.

7.1.11______/______Test leads and ground devices removed.

Attachment Cont'd: Megger Test Data Sheet

7.2 LOADS

Loads (Tag No.) / Continuity (Motors Only) / Test Connections / Megohms

Acceptance Criteria: Equal to or greater than one megohms per KV of rated voltage in step 5.2 plus one megohm, or as specified on Work Order.

7.2.8 ______/______Test leads and ground devices removed.

Attachment Cont'd: Megger Test Data Sheet

Remarks: ______

Test Personnel: ______Date: ______

Test Personnel: ______Date: ______

Data Reviewed and Approved: ______Date: ______Work Group Supervisor

Revision History

Revision Number / Approval Date / Name / Changes
R 0 / TBD / Jerry Wayne / Initial Draft
R 0 / TBD / Gwen Holladay / Edits

[D1]A comma makes this easier to read--is it appropriate?

[D2]Is a statoscope interchangeable with a hot stick? "Hot stick" seems to be more commonly used online.

[D3]Or "after you apply"

[D4]Warning: Do not defeat designed protection features while performing the work.

[D5]Is "good" specific enough?

[D6]"for example if you are"

[D7]Is this the same as the Work Order on p. 4, section 2?

[D8]"that is giving" or "that gives"?

[D9]Where? on the Megger Test Data Sheet?

[D10]unless the value displayed is "1" in the first (left-hand) position and the other positions are blank. In this case, record the value as "Infinity," "INF," or the infinity symbol.

[D11]1. "If you remove an MCC drawout unit" or If an MCC drawout unit has been removed"

2. I included MCC in Sect. 6, Definitions and Acronyms.

[D12]"have"? "display"?

[D13]on the Work Order? For each machine to be tested?

[D14]What does this stand for?

[D15]Should this be Attachment A:Megger Test Data Sheet?

[D16]Is it one minute each or one minute total?

[D17]Does this need to be in boldface?

[D18]"test results"?

[D19]No document number?