Transformer Testing Reference

Leakage Reactance

Updated 2026-10-24

RelationshipsLeakage Reactance is governed by IEEE/IEC C57.15-2017, IEEE C57.12.90-2021 and applies to no listed equipment.IEEE/IEC International Standard: Power transformers, Part 21: Standard requirements, terminology, and test code for step-voltage regulatorsIEEE/IEC C57.15-2017IEEE Standard Test Code for Liquid-Immersed Distribution, Power, and Regulating TransformersIEEE C57.12.90-2021Leakage ReactanceLeakage Reactance
Relationships. Governing standards on the left, equipment classes the test applies to on the right, as recorded for this entry.
Relationships: relationships recorded for this entry.
RelationshipEntry
Governing standardIEEE/IEC C57.15-2017 (IEEE/IEC International Standard: Power transformers, Part 21: Standard requirements, terminology, and test code for step-voltage regulators)
Governing standardIEEE C57.12.90-2021 (IEEE Standard Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers)

Data records

  • Leakage Reactance is specified for step voltage regulators in acceptance testing at clause 7.12.1.1.B.7 of ANSI/NETA ATS-2025. Value: step voltage regulators. Source: ANSI/NETA ATS-2025, clause 7.12.1.1.B.7. Verified 2026-10-13. Record tests.leakage-reactance.equipment.regulator.acceptance
  • Leakage Reactance is specified for liquid-filled transformers in acceptance testing at clause 7.2.2.B.10 of ANSI/NETA ATS-2025. Value: liquid-filled transformers. Source: ANSI/NETA ATS-2025, clause 7.2.2.B.10. Verified 2026-10-13. Record tests.leakage-reactance.equipment.transformer-fluid.acceptance
  • Leakage Reactance is specified for liquid-filled transformers in maintenance testing at clause 7.2.2.B.10 of ANSI/NETA MTS-2023. Value: liquid-filled transformers. Source: ANSI/NETA MTS-2023, clause 7.2.2.B.10. Verified 2026-10-13. Record tests.leakage-reactance.equipment.transformer-fluid.maintenance
  • Leakage Reactance is addressed in ANSI/NETA ATS-2025. Source: ANSI/NETA ATS-2025, clause 7.12.1.1.B.7. Verified 2026-10-13. Record tests.leakage-reactance.governed-by.ansi-neta-ats
  • Leakage Reactance is addressed in ANSI/NETA MTS-2023. Source: ANSI/NETA MTS-2023, clause 7.2.2.B.10. Verified 2026-10-13. Record tests.leakage-reactance.governed-by.ansi-neta-mts
  • Leakage Reactance is addressed in IEEE/IEC C57.15-2017. Source: IEEE/IEC C57.15-2017, clause 9.6.4.3.2. Verified 2026-10-13. Record tests.leakage-reactance.governed-by.ieee-c57-15
  • Clause 9.2 of IEEE C57.12.90-2021 notes that the tap position changes both the load losses and the impedance, that a rise in temperature raises the resistive loss and lowers the stray loss, and that, because the test runs at a low power factor, a phase-angle error in the metering instruments materially affects the measured loss. Source: IEEE C57.12.90-2021, clause 9.2. Verified 2026-10-24. Record tests.leakage-reactance.ieeec57-12-90.factors
  • IEEE C57.12.90-2021 defines impedance voltage as the voltage required to circulate rated current through one winding while the other winding is short-circuited, with the windings connected for rated voltage; it is stated relative to the energized winding's rated voltage and resolves into an in-phase resistance drop and a quadrature reactance drop that combine as a phasor sum. Source: IEEE C57.12.90-2021, clause 9.1. Verified 2026-10-24. Record tests.leakage-reactance.ieeec57-12-90.impedance-voltage-definition
  • Clause 9.4.3 of IEEE C57.12.90-2021 separates impedance voltage into a resistance component, which is corrected to the reference temperature, and a reactance component, which is independent of temperature, and recombines them as a phasor sum. Source: IEEE C57.12.90-2021, clause 9.4.3. Verified 2026-10-24. Record tests.leakage-reactance.ieeec57-12-90.reactive-component
  • The test method is named Leakage Reactance. Value: Leakage Reactance. Source: Electrical Testing Reference editorial taxonomy, 2026-10 edition. Verified 2026-10-13. Record tests.leakage-reactance.title

Sources

  • ANSI/NETA ATS-2025, Acceptance Testing Specifications for Electrical Power Equipment and Systems, 2025 edition, NETA. Cited: clause 7.12.1.1.B.7; clause 7.2.2.B.10. Held as: Purchased single-user copy. Publisher page
  • ANSI/NETA MTS-2023, Maintenance Testing Specifications for Electrical Power Equipment and Systems, 2023 edition, NETA. Cited: clause 7.2.2.B.10. Held as: Purchased single-user copy. Publisher page
  • Electrical Testing Reference editorial taxonomy, Electrical Testing Reference editorial taxonomy of test methods, 2026-10 edition, Electrical Testing Reference. Held as: Own observation.
  • IEEE C57.12.90-2021, Test Code for Liquid-Immersed Distribution, Power and Regulating Transformers, 2021 edition, IEEE. Cited: clause 9.2; clause 9.1; clause 9.4.3. Held as: Purchased single-user copy.
  • IEEE/IEC C57.15-2017, Requirements, Terminology and Test Code for Step-Voltage Regulators, 2017 edition, IEEE. Cited: clause 9.6.4.3.2. Held as: Purchased single-user copy. Publisher page

Obtaining the documents

Changelog (15 entries)
DateRevisionChange
2026-10-24created (tests.leakage-reactance.ieeec57-12-90.factors)
2026-10-24revised (tests.leakage-reactance.ieeec57-12-90.factors)
2026-10-24review_status unreviewed -> software_reviewed (tests.leakage-reactance.ieeec57-12-90.factors)
2026-10-24created (tests.leakage-reactance.ieeec57-12-90.impedance-voltage-definition)
2026-10-24revised (tests.leakage-reactance.ieeec57-12-90.impedance-voltage-definition)
2026-10-24review_status unreviewed -> software_reviewed (tests.leakage-reactance.ieeec57-12-90.impedance-voltage-definition)
2026-10-24created (tests.leakage-reactance.ieeec57-12-90.reactive-component)
2026-10-24review_status unreviewed -> software_reviewed (tests.leakage-reactance.ieeec57-12-90.reactive-component)
2026-10-13created (tests.leakage-reactance.equipment.regulator.acceptance)
2026-10-13created (tests.leakage-reactance.equipment.transformer-fluid.acceptance)
2026-10-13created (tests.leakage-reactance.equipment.transformer-fluid.maintenance)
2026-10-13created (tests.leakage-reactance.governed-by.ansi-neta-ats)
2026-10-13created (tests.leakage-reactance.governed-by.ansi-neta-mts)
2026-10-13created (tests.leakage-reactance.governed-by.ieee-c57-15)
2026-10-13created (tests.leakage-reactance.title)

Cite this page

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

"Leakage Reactance." Transformer Testing Reference. 2026-10-24. https://www.transformertestingreference.com/tests/leakage-reactance/.