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Field Testing & Twin SaaS
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#07Power & Distribution Transformer Inspection

Project Framework (report reference): IEC 60364-4-41Applicable Standard: IEC 60076 / NFPA 70B
Module Field Guides, Standard Selection & Tutorials (3)Browse All 93+ Guides →
1 · Field Measurement ProcedureHow to Measure & Test Transformer Inspection on Site: Step-by-Step Field Procedure (IEC 60076 / NFPA 70B)2 · Standards & Limit TablesWhich Standard Applies to Transformer Inspection? Acceptance Limits, Annex Tables & Regional Equivalents (IEC 60076 / NFPA 70B)3 · OhmCert Tutorial & Case StudyHow to Complete a Transformer Inspection Certificate in OhmCert: Worked Case Study & Troubleshooting

Multi-Asset / Multi-Point Equipment Schedule

Inspect multiple transformers, panels, rooms, motors, or RCDs in this module without overwriting previous assets. Each item receives a permanent QR Sticker UID preserved across annual audits.

Sticker UID: OC-TRAN-3A5D
Plant & SLD (Auto-SLD)

Standard Limits, Equations & Space Presets

IEC 60076, IEEE C57.104-2019 Dissolved Gas Analysis (DGA) Condition 1-4 thresholds, NETA ATS Turns Ratio (+/-0.5%), Winding Resistance Imbalance (<=2%), and Oil Breakdown Voltage (ASTM D877).

One-Click Normative Presets (Auto-fills Target Limits)

Measured Inputs

Calculated / Evaluated Results

Acceptance: TTR within +/-0.5% of nameplate (NETA ATS 7.2.2), insulation resistance >= 1 MOhm per kV of rated voltage (IEEE 43 / NETA ATS Table 100.5), top-oil rise within the nameplate class (IEEE C57.12.00) and dissolved gas condition per IEEE C57.104-2019.

Pending / Not tested — results stay neutral until valid measured values are entered.

  • Rated HV Current & Actual Load

    -

    Three-phase primary nominal current In = kVA / (sqrt(3) x kV) per IEC 60076-1.

    Pending

  • Loading Level

    - %

    Not tested - enter the measured value. Acceptance: Continuous loading <= 80% of rating preserves insulation life (IEC 60076-7 / IEEE C57.91 loading guide) [IEEE C57.91 / IEC 60076-7]

    Pending

  • Top Oil Rise over Ambient

    - degC

    Not tested - enter the measured value. Acceptance: Rise <= 65 degC per the nameplate temperature rise class [IEEE C57.12.00 / IEC 60076-2]

    Pending

  • Turns Ratio (TTR) Deviation

    - %

    Not tested - enter the measured value. Acceptance: Within +/-0.5% of the nameplate ratio on every tap [NETA ATS 7.2.2 / IEEE C57.12.90]

    Pending

  • Winding Resistance Imbalance

    - %

    Not tested - enter the measured value. Acceptance: Phase-to-phase deviation <= 1-2% of the average (NETA field criterion) [NETA ATS 7.2.1.2 / IEEE C57.152]

    Pending

  • Insulation Resistance vs (kV + 1) MOhm Minimum

    -

    Not tested - enter the measured value. Acceptance: IR_min = (Rated kV + 1) MOhm, corrected to 20 degC [IEEE 43 / IEEE C57.152 / NETA ATS Table 100.5]

    Pending

  • Oil Dielectric Breakdown

    - kV

    Not tested - enter the measured value. Acceptance: In-service mineral oil >= 26 kV (ASTM D877, 0.1 in gap) [IEEE C57.106 / ASTM D877]

    Pending

  • Dissolved Gas Condition (TDCG)

    -

    Not tested - Condition 1 (<= 720 ppm): normal operation. [IEEE C57.104-2019]

    Pending

Verification Checklist (0 / 18)

Pending

  • 1Nameplate kVA, vector group (e.g. Dyn11), impedance %Uk and tap voltages verified against SLD [IEC 60076-1]

  • 2Main tank, conservator, radiator fins, drain valves and flange gaskets free of oil seepage

  • 3Conservator oil level gauge (MOG) and low-oil alarm contact tested

  • 4Dehydrating silica gel breather active (blue/orange, < 30% saturated) and oil seal cup filled

  • 5Buchholz gas/surge relay float alarm and flap trip contacts proven to trip HV breaker

  • 6Pressure Relief Device (PRD) / sudden pressure relay micro-switch and visual flag verified

  • 7Oil Temperature Indicator (OTI) and Winding Temperature Indicator (WTI) alarm/trip stages calibrated

  • 8Forced cooling fans (ONAF) and oil pumps tested in manual and automatic WTI start modes

  • 9De-energised (DETC) or On-Load Tap Changer (OLTC) operation counter, oil diverter and tap position recorded

  • 10Turns Ratio (TTR) measured on all taps within +/-0.5% of nameplate ratio [NETA ATS 7.2.2]

  • 11Winding DC resistance measured on all phases (imbalance <= 1-2%) and core demagnetised after test

  • 12HV-to-LV, HV-to-E, and LV-to-E Insulation Resistance and Polarization Index (PI) tested [IEEE C57.152]

  • 13HV and LV porcelain/polymer bushings clean, free of cracks, corona tracking, or oil weeping

  • 14Transformer star-point neutral bushing earthing conductor and frame dual-earth bonds verified (<= 0.2 Ohm)

  • 15HV plug-in elbows / cable terminations and LV busbar flags torque-checked and IR thermography scanned

  • 16Insulating oil sample drawn for ASTM D877/D1816 breakdown, moisture (ppm), acidity, and IEEE C57.104 DGA

  • 17Oil containment bund pit (>= 110% oil volume), flame-trap gravel bed, and fire deluge/barriers intact

  • 18Transformer bay interlock keys (Castell/Kirk key scheme between HV CB, LV ACB and door) verified

General Notes

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Free plan: 5 of 5 inspections / calculations left this month.