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OhmCert2026
Field Testing & Twin SaaS
🇬🇧 Full UI + PDF + National Standard Mapping: UI + PDF in English. Normative references follow international IEC 60364, BS 7671:2018+A2:2022, IEEE, and NFPA 70E/70B.
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#29AC Induction Motor & VFD Field Diagnostic Report

Project Framework (report reference): IEC 60364-4-41Applicable Standard: IEC 60034-1 / NEMA MG-1 / IEEE 43
Module Field Guides, Standard Selection & Tutorials (3)Browse All 93+ Guides →
1 · Field Measurement ProcedureHow to Measure & Test Motor & VFD Diagnostics on Site: Step-by-Step Field Procedure (IEC 60034-1 / NEMA MG-1 / IEEE 43)2 · Standards & Limit TablesWhich Standard Applies to Motor & VFD Diagnostics? Acceptance Limits, Annex Tables & Regional Equivalents (IEC 60034-1 / NEMA MG-1 / IEEE 43)3 · OhmCert Tutorial & Case StudyHow to Complete a Motor & VFD Diagnostics 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-MOTO-AED5
Plant & SLD (Auto-SLD)

Standard Limits, Equations & Space Presets

NEMA MG-1 §14.36, IEC 60034-1, IEEE Std 43, and IEC 60034-25 define field acceptance limits for 3-phase induction motors and VFD drives: even 3.5% phase voltage unbalance increases winding temperature rise by ~25% (2 x %V_unb^2).

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

Measured Inputs

Calculated / Evaluated Results

Evaluates 3-phase industrial motors and Variable Frequency Drives (VFD): terminal voltage unbalance & exact NEMA MG-1 §14.36 thermal derating factor (extra rotor/stator heating ~ 2 x %V_unb^2), phase current unbalance, 3-phase winding DC ohmic resistance balance (<= 2%), IEEE 43 stator insulation R_40C, bearing temperature, and IEC 60034-25 VFD shaft EDM voltage.

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

  • Terminal Phase Voltage Unbalance & NEMA MG-1 Derating

    -

    Not tested - enter the measured value. Acceptance: V_unb <= 1.0% without derating (<= 2.0% max field limit with NEMA MG-1 derating; > 5.0% prohibited) [NEMA MG-1 §14.36 / IEC 60034-1 §7.2]

    Pending

  • 3-Phase Current Unbalance

    - %

    Not tested - enter the measured value. Acceptance: Phase current unbalance <= 10.0% at normal operating load [ANSI/NETA MTS §7.15.1]

    Pending

  • Operating Load Factor vs NEMA Derated Capacity

    -

    Not tested - enter the measured value. Acceptance: I_avg / I_FLC <= 100% x NEMA Derating Factor [IEC 60034-1 / NEMA MG-1]

    Pending

  • 3-Phase Stator Winding DC Resistance Unbalance

    -

    Not tested - enter the measured value. Acceptance: Max deviation from average phase resistance <= 2.0% (detects shorted turns or loose terminal lugs) [IEEE Std 112 / ANSI/NETA MTS §7.15.1]

    Pending

  • Stator Winding Insulation Resistance R_40C

    - MOhm

    Not tested - enter the measured value. Acceptance: R_40C >= 5 MOhm minimum for LV (< 1 kV) stators (>= 100 MOhm recommended for critical drives) [IEEE Std 43-2013 Table 2]

    Pending

  • Bearing Housing Operating Temperature (DE / NDE)

    - degC

    Not tested - enter the measured value. Acceptance: Bearing housing temperature <= 80 degC continuous grease-lubricated limit [IEEE 841 / ISO 10816]

    Pending

  • VFD Shaft-to-Frame EDM Peak Voltage

    - Vpk

    Not tested - enter the measured value. Acceptance: V_shaft <= 5.0 Vpk to prevent capacitive EDM fluting of motor bearings (install AEGIS shaft grounding ring / insulated NDE bearing if exceeded) [IEC 60034-25 / NEMA MG-1 Part 31]

    Pending

Verification Checklist (0 / 12)

Pending

  • 1Motor nameplate data (kW, V, Hz, I_FLC, cos phi, RPM, IE efficiency class, Insulation Class F/H, IP rating) verified against duty

  • 2Motor efficiency class meets IEC 60034-30-1 regulatory minimum (IE3 / IE4) and cooling fan cowl / stator fins unobstructed

  • 3Terminal box gasket intact, brass/EMC cable glands tight, and star/delta link bars torqued evenly without overheating

  • 4Protective earth (PE) terminal inside motor box and external frame supplementary earth lug bonded (< 0.1 Ohm)

  • 5Motor overload protection (MPCB / electronic thermal relay / VFD I^2t parameter) set <= 1.00 x I_FLC (for IEC Service Factor 1.0 motors)

  • 6PTC thermistor / PT100 stator & bearing RTD protection wired to trip VFD/contactor on overtemperature

  • 7For VFD-fed motors: symmetrical 360-degree EMC shielded motor cable terminated with EMC glands at both VFD and motor ends [IEC 60034-25]

  • 8For VFD cable lengths > 50-100 m: dV/dt filter or sine-wave filter installed to limit reflected-wave voltage spikes (< 1300 Vpk on 400 V motors)

  • 9Insulated NDE ceramic/coated bearing and/or carbon-microfiber shaft grounding brush installed on VFD motors >= 75-90 kW

  • 10VFD DC-link capacitors, heatsink cooling fans, and cabinet air filters inspected and free of conductive dust/oil mist

  • 11Mechanical shaft alignment, coupling elastomer condition, and overall vibration velocity (ISO 20816-3 <= 2.8-4.5 mm/s RMS) verified

  • 12Local lockable emergency isolator / maintenance safety switch within sight of the driven machine verified functional

General Notes

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