Protective Relay Reference

Relay 51 Time Overcurrent Test

Updated 2026-10-24

RelationshipsRelay 51 Time Overcurrent Test is governed by IEEE C37.112-2018 and applies to no listed equipment.IEEE Standard for Inverse-Time Characteristics Equations for Overcurrent RelaysIEEE C37.112-2018Relay 51 Time Overcurrent TestRelay 51 Time Overcurrent Test
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 C37.112-2018 (IEEE Standard for Inverse-Time Characteristics Equations for Overcurrent Relays)

Data records

  • Relay 51 Time Overcurrent Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.15 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. Source: ANSI/NETA ATS-2025, clause 7.9.1.B.3.15. Verified 2026-10-13. Record tests.relay-51-time-overcurrent-test.equipment.relay.acceptance
  • Relay 51 Time Overcurrent Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.15 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. Source: ANSI/NETA MTS-2023, clause 7.9.1.B.3.15. Verified 2026-10-13. Record tests.relay-51-time-overcurrent-test.equipment.relay.maintenance
  • Relay 51 Time Overcurrent Test is addressed in ANSI/NETA ATS-2025. Source: ANSI/NETA ATS-2025, clause 7.9.1.B.3.15. Verified 2026-10-13. Record tests.relay-51-time-overcurrent-test.governed-by.ansi-neta-ats
  • Relay 51 Time Overcurrent Test is addressed in ANSI/NETA MTS-2023. Source: ANSI/NETA MTS-2023, clause 7.9.1.B.3.15. Verified 2026-10-13. Record tests.relay-51-time-overcurrent-test.governed-by.ansi-neta-mts
  • A timing check that uses the conformance criteria of IEEE C37.112-2018 places its test points inside the range of multiples of pickup that clause 3.4 names and judges the shape of the curve against the conformance bands, while timing accuracy is judged against the relay manufacturer tolerance because the bands are not accuracy limits. Source: IEEE C37.112-2018, clause 3.4. Verified 2026-10-24. Record tests.relay-51-time-overcurrent-test.ieeec37-112.conformance-check
  • For a time-overcurrent element set to one of the standard characteristics of IEEE C37.112-2018, the expected operate time at a test multiple of pickup is computed from the trip equation of clause 3.2 with the relay time dial, which gives the reference against which a measured operate time is compared. Source: IEEE C37.112-2018, clause 3.2. Verified 2026-10-24. Record tests.relay-51-time-overcurrent-test.ieeec37-112.expected-time
  • Tables A.1 and A.2 of IEEE C37.112-2018 record measured constants for two induction relay models that differ from the Table 1 values, which shows that the standard characteristics are mean shapes rather than the exact curve of any particular electromechanical relay. Source: IEEE C37.112-2018, clause Annex A, Tables A.1 and A.2. Verified 2026-10-24. Record tests.relay-51-time-overcurrent-test.ieeec37-112.induction-relay-curves
  • When a relay provides the optional reset characteristic of IEEE C37.112-2018, reset timing is checked at multiples of pickup below pickup, over the band that clause 3.4 names, using the reset equation of clause 3.2 with the reset constant scaled by the time dial. Source: IEEE C37.112-2018, clause 3.2, 3.3, 3.4. Verified 2026-10-24. Record tests.relay-51-time-overcurrent-test.ieeec37-112.reset-check
  • The test method is named Relay 51 Time Overcurrent Test. Value: Relay 51 Time Overcurrent Test. Source: Electrical Testing Reference editorial taxonomy, 2026-10 edition. Verified 2026-10-13. Record tests.relay-51-time-overcurrent-test.title

Sources

  • ANSI/NETA ATS-2025, Acceptance Testing Specifications for Electrical Power Equipment and Systems, 2025 edition, NETA. Cited: clause 7.9.1.B.3.15. 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 7.9.1.B.3.15. 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 C37.112-2018, IEEE Standard for Inverse-Time Characteristics Equations for Overcurrent Relays, 2018 edition, IEEE. Cited: clause 3.4; clause 3.2; clause Annex A, Tables A.1 and A.2; clause 3.2, 3.3, 3.4. Held as: Purchased single-user copy.

Obtaining the documents

Changelog (14 entries)
DateRevisionChange
2026-10-24created (tests.relay-51-time-overcurrent-test.ieeec37-112.conformance-check)
2026-10-24review_status unreviewed -> software_reviewed (tests.relay-51-time-overcurrent-test.ieeec37-112.conformance-check)
2026-10-24created (tests.relay-51-time-overcurrent-test.ieeec37-112.expected-time)
2026-10-24review_status unreviewed -> software_reviewed (tests.relay-51-time-overcurrent-test.ieeec37-112.expected-time)
2026-10-24created (tests.relay-51-time-overcurrent-test.ieeec37-112.induction-relay-curves)
2026-10-24review_status unreviewed -> software_reviewed (tests.relay-51-time-overcurrent-test.ieeec37-112.induction-relay-curves)
2026-10-24created (tests.relay-51-time-overcurrent-test.ieeec37-112.reset-check)
2026-10-24revised (tests.relay-51-time-overcurrent-test.ieeec37-112.reset-check)
2026-10-24review_status unreviewed -> software_reviewed (tests.relay-51-time-overcurrent-test.ieeec37-112.reset-check)
2026-10-13created (tests.relay-51-time-overcurrent-test.equipment.relay.acceptance)
2026-10-13created (tests.relay-51-time-overcurrent-test.equipment.relay.maintenance)
2026-10-13created (tests.relay-51-time-overcurrent-test.governed-by.ansi-neta-ats)
2026-10-13created (tests.relay-51-time-overcurrent-test.governed-by.ansi-neta-mts)
2026-10-13created (tests.relay-51-time-overcurrent-test.title)

Cite this page

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

"Relay 51 Time Overcurrent Test." Protective Relay Reference. 2026-10-24. https://www.protectiverelayreference.com/tests/relay-51-time-overcurrent-test/.