Transformer Testing Reference

Data record tests.insulation-resistance.equipment.transformer-large.acceptance

Verified 2026-10-29 Confidence: High

Insulation Resistance is specified for large air-cooled dry-type transformers in acceptance testing at clause 7.2.1.2.B.2 of ANSI/NETA ATS-2025. The clause calls for insulation-resistance tests winding-to-winding and each winding-to-ground at the manufacturer's test voltage, with the dielectric absorption ratio and the polarization index calculated.

Value: large air-cooled dry-type transformers

ProvenanceANSI/NETA ATS-2025 supports data record tests.insulation-resistance.equipment.transformer-large.acceptance, which is cited on the entry Insulation Resistance.SOURCEANSI/NETA ATS-2025ANSI/NETA ATS-2025Licensed standard, clause 7.2.1.2.B.2DATA RECORDtests.insulation-resistance.equipment.transformer-large.acceptancetests.insulation-resista..Verified 2026-10-29ENTRYInsulation ResistanceInsulation ResistanceNo revisions
Provenance. Where this record comes from and where it is used: the cited source, the record itself and the entry that cites it.
Provenance: the chain from source to entry.
StepItemDetail
SourceANSI/NETA ATS-2025Licensed standard, clause 7.2.1.2.B.2
Data recordtests.insulation-resistance.equipment.transformer-large.acceptanceVerified 2026-10-29
EntryInsulation ResistanceNo revisions
Subject
Insulation Resistance (Test methods)
Kind
Equipment fact
Source
ANSI/NETA ATS-2025, clause 7.2.1.2.B.2, Acceptance Testing Specifications for Electrical Power Equipment and Systems, NETA. Publisher page for ANSI/NETA ATS-2025Publisher information page
Also stated in
  • FIST 4-7, section 6.1.25.1, page 70 (August 2023).
    Read the reference passage

    6.1.25.1 Excitation Transformer

    "Once the visual inspection is complete and no unusual conditions have been identified, the transformer will be ready for the following electrical test. The main electrical test to be performed is the insulation resistance test with phase-to-phase and phase-to-ground."

    FIST 4-7, section 6.1.25.1, page 70, August 2023. Agency copy of FIST 4-7

    The current standard governs; this passage is a public-domain description of the practice dated August 2023.

History

Every recorded change to this data record, oldest first.
DateChange
2026-10-29created

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Cite the governing standard for the fact itself; cite this page as the finding aid.

"Data record tests.insulation-resistance.equipment.transformer-large.acceptance." Transformer Testing Reference. 2026-10-29. https://www.transformertestingreference.com/data/tests.insulation-resistance.equipment.transformer-large.acceptance/.