Megger Testing of Busses, MCCs, and Distribution Panels ...



Effective Date: TBDPrepared by:Jerry WayneDate: ____________________Reviewed by: Gwen Holladay_________________________________ Date: ____1/25/11______Approved by: ___________________________________________________ Date: ____________________Required review frequency: TBDTable of Contents TOC \h \z \t "Heading 1,1,Heading 2,2,Attachment,3" 1.Purpose and Scope PAGEREF _Toc283296345 \h 42.Acceptance Criteria PAGEREF _Toc283296346 \h 43.Special Tools and Materials PAGEREF _Toc283296347 \h 43.1Tools PAGEREF _Toc283296348 \h 43.2Materials PAGEREF _Toc283296349 \h 44.Precautions, Limitations, and Notes PAGEREF _Toc283296350 \h 54.1Precautions PAGEREF _Toc283296351 \h 54.2Limitations PAGEREF _Toc283296352 \h 54.3Notes PAGEREF _Toc283296353 \h 55.Prerequisites PAGEREF _Toc283296354 \h 65.1Planner PAGEREF _Toc283296355 \h 65.2Electricians PAGEREF _Toc283296356 \h 66.Definitions and Acronyms PAGEREF _Toc283296357 \h 77.Instructions PAGEREF _Toc283296358 \h 77.1Busses / Motor Control Centers / Distribution Panels PAGEREF _Toc283296359 \h 77.2Loads PAGEREF _Toc283296360 \h 9HYPERLINK \l "_Toc283296361"8.References PAGEREF _Toc283296361 \h 1098.1Development References PAGEREF _Toc283296362 \h 108.2Performance References PAGEREF _Toc283296363 \h 109.Attachments PAGEREF _Toc283296364 \h 10Attachment A:Megger Test Data Sheet PAGEREF _Toc283296365 \h 11 List of Tables TOC \h \z \c "Table" Table 1: Signature Box PAGEREF _Toc283296366 \h 7Table 2: Test Voltages PAGEREF _Toc283296367 \h 8ReviewsWriter completes this section and deletes from final version after approval. Review comments are stored in <type location where comments are stored.>.< In the Name column, list the names of reviewers you plan to review your document.>Internal ReviewStakeholder ReviewPurpose and ScopeThe purpose of this procedure is to provide instructions for performing insulation resistance (megger) testing of busses, motor control centers (MCCs), and distribution panels. This procedure provides the minimum guidelines and acceptance criteria necessary to ensure that you perform meggering is performed in a safely and consistently manner.Acceptance CriteriaThe following acceptance criteria must be met to complete the procedure. The minimum acceptable value for insulation resistance (R min.) in megohms between phase-to-phase (busses and feeder cables) and phase-to-ground should equal or exceed one of the following values:R min. should be equal to or greater than one megohm per KV of rated voltage of equipment plus one megohm.The the minimum value specified by the equipment manufacturer if different from above, as specified on the applicable Work Order.Special Tools and MaterialsUse the following special tools and materials to perform this procedure.ToolsThe following special tools are required:Statascope Statoscope (hot stick) (as required)Ground stick (as required)Ground straps/jumpersClass II Rrubber insulated gloves (600V or greater) with leather protectorsFire retardant coverallsVoltmeterContinuity checkerMeggerMaterialsThe following special tools materials are required:NonePrecautions, Limitations, and NotesBefore performing the procedure, ensure you understand the following precautions, limitations, and notes.Precautions The following precautions shall be followed:To ensure the safety of personnel and accuracy of the test, Gground the test specimen to discharge the accumulated charges after application ofapplying 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 or component damage when working on energized equipment.Ensure that designed protection features are not defeated during performance of the work. Wear Class II rubber gloves and fire retardant coveralls when meggering at 1001 volts or greater, including when connecting and disconnecting meggering equipment. Connect ground lead first, and then HV lead. Disconnect ground lead last.Ensure thatUse a good connection to earth ground is used for both meggering and discharge of equipment under test.Warn and keep other personnel away from equipment during insulation testing and a capacitance discharge. Utilize safety barriers and flagging when appropriate.Do not perform insulation test in a flammable or explosive atmosphere.LimitationsNoneNotesThe following information may be used while performing the procedure:Do not record readings within the body of this procedure if you are meggering is being performed to obtain "Information Only" type data, as in case of trouble shooting.Do not record readings here if you are meggering is being performed as part of another approved procedure. Report discrepancies or unsatisfactory results to the Work Group Supervisor for follow-up actions. Record problems found in the "Remarks" section of work package.Read the analog megger on the scale giving best resolution, and record. 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 on the highest available range), erratic, or in transit.Record the actual value displayed value on the digital megger, except that the word "Infinity", "INF" or the infinity symbol should be used when the display shows the digit "1" in the first (left hand) position with the other positions blank.If an MCC drawout unit is removed, 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. They should be less than 10 ohms resistance.Inspect breaker stabs for signs of overheating by looking for discoloration or signs of arcing. PrerequisitesThe following prerequisites must be met before performing this procedure.PlannerThe planner must enter the following information:Work Order No.: __________________________________Component Tag No.: ______________________________Unit No.: ____________________________________________Serial No.: __________________________________________ElectriciansPersonnel 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 NameSign NameInitialsRACF IDTable 1: Signature BoxEnter following information on REF _Ref283209354 \r \h Attachment A: REF _Ref283209373 \h Megger Test Data Sheet:.Equipment Rated VoltageTest VoltageM&TE numbers and Calibration Due DatesDefinitions and AcronymsCR (from bottom of page 9)Live-Dead-Live (L-D-L)Motor Control Centers (MCCs)InstructionsThe procedures below contain instructions for the following tasks:Busses / MCCs Motor Control Centers / Distribution PanelsLoadsBusses / Motor Control Centers / Distribution PanelsUse this section to perform megger testing of load center busswork that has been isolated from all of its respective loads. Refer to Section 7.2 for megger testing of individual loads.Ensure Switch power supply breaker to is in "Open" or "Off" position.Use L-D-L method to de-energize Ensure load side connections of power supply breaker are de-energized by electrical measurements. Use L-D-L method.Isolate Ensure all loads associated with buss to be tested. have been isolated.Disconnect high high-voltage sensitive devices and potential transformers from buss to be tested.Record and verify leads lifted, and fuses removed on Verification Sheet. Verify that information is correct, and have a Use second person man as verifyier the information.Use table below for appropriate Test Voltages.Bus VoltageTest Voltage DC4805002500250041605000690050001380010000 the information is correct. ms?ine. "Hot sticks" seems to be more commonly used. CCs he following signature box Table 2: Test VoltagesMegger busswork phase-to-phase then phase-to-ground for one minute, until readings are stable, or until acceptance criteria is reached.Record readings on REF _Ref283209354 \r \h Attachment A: REF _Ref283209373 \h Megger Test Data Sheetthe Data Sheet.Ground and discharge each phase pare readings taken with the acceptance criteria given in Section 2.Remove all test leads and grounding devices. Record on REF _Ref283209354 \r \h Attachment A: REF _Ref283209373 \h Megger Test Data SheetMegger Test Data Sheet.Connect high voltage sensitive devices, and potential transformers.Record and verify leads landed and fuses installed on REF _Ref283209354 \r \h Attachment A: REF _Ref283209373 \h Megger Test Data SheetVerification Sheet. Have a Use second personman as verify the informationier.Perform a post work close-out inspection to ensure that all tools and foreign material have been removed.LoadsMegger testing is only required for power circuits. Megger testing instrument and control circuits is not required, or desirable.Use applicable electrical drawings to determine what loads to megger test.Record tag numbers and test connections for each load to be meggered on REF _Ref283209185 \r \h Attachment A: REF _Ref283209199 \h Megger Test Data Sheet.Ensure Switch circuit breaker for each load tois in "Open" or "Off" position.Use L-D-L method to de-energize Ensure load side connections of each breaker are de-energized by electrical measurements. Use L-D-L method.For motors only, perform phase-to-phase continuity checks between each phase and record "Sat" or "Unsat" on REF _Ref283208797 \r \h Attachment A: REF _Ref283208827 \h Megger Test Data Sheet.Phase-to-phase megger readings are only required for feeder cables to other MCCs or distribution panels. The breaker on the opposite end of the feeder cable must be open to obtain satisfactory readings.Megger each load phase-to-ground and, only if required, phase-to-phase for each load for approximately one minute or until acceptance criteria is reached.Ground and discharge each load tested.Remove all test leads and grounding devices. Record on REF _Ref283209004 \r \h Attachment A: REF _Ref283209016 \h Megger Test Data Sheet.Review all readings taken and determine if they meet acceptance criteria as given in Section 2.Contact your supervisor and report any equipment deficiencies. Write a CR for repair or evaluation of the equipment.ReferencesDevelopment references are documents used to develop the procedure. Performance references are documents referenced within the procedure.Development ReferencesIEEE Std 43-2000 Recommended Practice for Testing Insulation Resistance of Rotating MachineryIEEE Std 62-1974 Guide for Field Testing Power Apparatus InsulationPerformance ReferencesGeneration Safety HandbookLUM-FFA-REL-0014 Standard of Human Performance Improvement (LUM-FFA-REL-0014)LUM-FFA-SAF-0002 Hazardous Energy Control Program: LOTOV-Lockout/Tagout /Verify (MSDS) Material Safety Data Sheet (MSDS)Attachments The following attachments are appended to this procedure. REF _Ref283208797 \r \h Attachment A: REF _Ref283208797 \h Megger Test Data SheetMegger Test Data Sheet5.2Equipment Rated Voltage: __________ VACTest Voltage: ___________ VDC7.1Busses / Motor Control CentersMCCs / Distribution PanelsEquipment 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.Megger Test Data Sheet7.2 LOADS Loads (Tag No.) Continuity (Motors Only) Test Connections MegohmsAcceptance 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.Megger Test Data SheetRemarks: ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Test Personnel: ____________________________________________________________Date: ______________________Test Personnel: ____________________________________________________________Date: ______________________Data Reviewed and Approved: ___________________________________________Date: ______________________Work Group SupervisorRevision HistoryRevision NumberApproval DateNameChangesR 0TBDJerry WayneInitial DraftR 0TBDGwen HolladayEdits ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download