Data records
Each statement in Protective Relay Reference is recorded as a data record with its source, verification date, review status and history. The index lists 199 records by subject.
Test methods
Bolted connection resistance
| Record | Statement |
|---|---|
| tests.bolted-connection-resistance.equipment.relay.acceptance | Bolted Connection Resistance is specified for low-voltage ground-fault protection systems in acceptance testing at clause 7.14.B.1 of ANSI/NETA ATS-2025. Value: low-voltage ground-fault protection systems. |
| tests.bolted-connection-resistance.equipment.relay.maintenance | Bolted Connection Resistance is specified for low-voltage ground-fault protection systems in maintenance testing at clause 7.14.B of ANSI/NETA MTS-2023. Value: low-voltage ground-fault protection systems. |
Control and functional verification
| Record | Statement |
|---|---|
| tests.control-and-functional-verification.equipment.relay.acceptance | Control and Functional Verification is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.4 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.control-and-functional-verification.equipment.relay.maintenance | Control and Functional Verification is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.4 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
Ground fault protection performance
| Record | Statement |
|---|---|
| tests.ground-fault-protection-performance.equipment.relay.acceptance | Ground Fault Protection Performance is specified for low-voltage ground-fault protection systems in acceptance testing at clause 7.14.B.4 of ANSI/NETA ATS-2025. Value: low-voltage ground-fault protection systems. |
| tests.ground-fault-protection-performance.equipment.relay.maintenance | Ground Fault Protection Performance is specified for low-voltage ground-fault protection systems in maintenance testing at clause 7.14.B of ANSI/NETA MTS-2023. Value: low-voltage ground-fault protection systems. |
Insulation resistance
| Record | Statement |
|---|---|
| tests.insulation-resistance.equipment.relay.acceptance | Insulation Resistance is specified for low-voltage ground-fault protection systems in acceptance testing at clause 7.14.B.2 of ANSI/NETA ATS-2025. Value: low-voltage ground-fault protection systems. |
| tests.insulation-resistance.equipment.relay.maintenance | Insulation Resistance is specified for low-voltage ground-fault protection systems in maintenance testing at clause 7.14.B of ANSI/NETA MTS-2023. Value: low-voltage ground-fault protection systems. |
Polarity test
| Record | Statement |
|---|---|
| tests.polarity-test.equipment.relay.acceptance | Polarity Test is specified for low-voltage ground-fault protection systems in acceptance testing at clause 7.14.B.5 of ANSI/NETA ATS-2025. Value: low-voltage ground-fault protection systems. |
| tests.polarity-test.equipment.relay.maintenance | Polarity Test is specified for low-voltage ground-fault protection systems in maintenance testing at clause 7.14.B of ANSI/NETA MTS-2023. Value: low-voltage ground-fault protection systems. |
Protective Relay Element Tests
| Record | Statement |
|---|---|
| tests.protective-relay-element-tests.equipment.drive.acceptance | Protective Relay Element Tests is specified for adjustable-speed drive systems in acceptance testing at clause 7.17.B.5 of ANSI/NETA ATS-2025. Value: adjustable-speed drive systems. |
| tests.protective-relay-element-tests.equipment.drive.maintenance | Protective Relay Element Tests is specified for adjustable-speed drive systems in maintenance testing at clause 7.17.B.5 of ANSI/NETA MTS-2023. Value: adjustable-speed drive systems. |
| tests.protective-relay-element-tests.equipment.generator.acceptance | Protective Relay Element Tests is specified for engine-generator emergency systems in acceptance testing at clause 7.22.1.B.2 of ANSI/NETA ATS-2025. Value: engine-generator emergency systems. |
| tests.protective-relay-element-tests.equipment.generator.maintenance | Protective Relay Element Tests is specified for engine-generator emergency systems in maintenance testing at clause 7.22.1.B.2 of ANSI/NETA MTS-2023. Value: engine-generator emergency systems. |
| tests.protective-relay-element-tests.equipment.motor.acceptance | Protective Relay Element Tests is specified for low-voltage motor starters in acceptance testing at clause 7.16.1.1.B.3 of ANSI/NETA ATS-2025. Value: low-voltage motor starters. |
| tests.protective-relay-element-tests.equipment.motor.maintenance | Protective Relay Element Tests is specified for low-voltage motor starters in maintenance testing at clause 7.16.1.1.B.4 of ANSI/NETA MTS-2023. Value: low-voltage motor starters. |
| tests.protective-relay-element-tests.equipment.network-protector.acceptance | Protective Relay Element Tests is specified for low-voltage network protectors in acceptance testing at clause 7.8.B.10 of ANSI/NETA ATS-2025. Value: low-voltage network protectors. |
| tests.protective-relay-element-tests.equipment.network-protector.maintenance | Protective Relay Element Tests is specified for low-voltage network protectors in maintenance testing at clause 7.8.B.10 of ANSI/NETA MTS-2023. Value: low-voltage network protectors. |
| tests.protective-relay-element-tests.equipment.relay.acceptance | Protective Relay Element Tests is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.2 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.protective-relay-element-tests.equipment.relay.maintenance | Protective Relay Element Tests is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.2 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.protective-relay-element-tests.governed-by.ansi-neta-ats | Protective Relay Element Tests is addressed in ANSI/NETA ATS-2025. |
| tests.protective-relay-element-tests.governed-by.ansi-neta-mts | Protective Relay Element Tests is addressed in ANSI/NETA MTS-2023. |
| tests.protective-relay-element-tests.governed-by.faa-ac-150-5345-10h | Protective Relay Element Tests is addressed in FAA AC 150/5345-10H. |
| tests.protective-relay-element-tests.governed-by.ieee-946 | Protective Relay Element Tests is addressed in IEEE 946-2020. |
| tests.protective-relay-element-tests.ieee1547-1.commissioning-criteria | The criteria for commissioning test CT3 in clause 8.2.3.3 of IEEE 1547.1-2020 are the limits of IEEE 1547-2018 and its clearing-time tables for the applicable abnormal performance category, applied as defaults unless the Area EPS operator specifies otherwise; a prerequisite is that the installation evaluation has already confirmed the settings that the AGIR or the Area EPS operator requires. |
| tests.protective-relay-element-tests.ieee1547-1.commissioning-trip-test | Commissioning test CT3 in clause 8.2.3.3 of IEEE 1547.1-2020 verifies cease to energize for undervoltage, overvoltage, underfrequency and overfrequency, each at the magnitude and clearing time that IEEE 1547-2018 and the AGIR specify, with the procedure being whatever the Area EPS operator requires and the details settled by mutual agreement. The clause observes that field tests of the abnormal voltage and frequency responses are complicated, so those responses are usually verified by type test, and it allows signal injection on a unit that has provisions for it. |
| tests.protective-relay-element-tests.ieee1547-1.commissioning-verification | Clause 8.2.3 of IEEE 1547.1-2020 makes verification of the DER's voltage and frequency tripping functions and of its cease-to-energize behavior mandatory at commissioning, and it allows signal injection where actual adjustment of the voltage and frequency is impractical. |
| tests.protective-relay-element-tests.ieee1547-1.poc-unit-verification | Table 72 of IEEE 1547.1-2020 shows that, for a fully compliant PoC unit, the mandatory voltage tripping requirement of IEEE 1547-2018 is verified through the design evaluations and the applied-settings read-back rather than through a field trip test, while a field frequency trip test depends on the outcome of the design evaluation. |
| tests.protective-relay-element-tests.ieee1547-1.production-trip-test | The production trip tests in clauses 7.2.2 and 7.3.2 of IEEE 1547.1-2020 connect the unit per the manufacturer, apply and record the manufacturer's trip and time settings with other settings at factory values, select one function at a time, move the source beyond the setting by a margin tied to the minimum required measurement accuracy so that only the selected function causes the trip, record the RMS magnitude or frequency and the clearing time, drive each phase in turn on multiphase units, and repeat for every function. |
| tests.protective-relay-element-tests.title | The test method is named Protective Relay Element Tests. Value: Protective Relay Element Tests. |
Relay 21 Distance Test
| Record | Statement |
|---|---|
| tests.relay-21-distance-test.equipment.relay.acceptance | Relay 21 Distance Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.2 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-21-distance-test.equipment.relay.maintenance | Relay 21 Distance Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.2 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-21-distance-test.governed-by.ansi-neta-ats | Relay 21 Distance Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-21-distance-test.governed-by.ansi-neta-mts | Relay 21 Distance Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-21-distance-test.title | The test method is named Relay 21 Distance Test. Value: Relay 21 Distance Test. |
Relay 25 Sync Check Test
| Record | Statement |
|---|---|
| tests.relay-25-sync-check-test.equipment.relay.acceptance | Relay 25 Sync Check Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.4 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-25-sync-check-test.equipment.relay.maintenance | Relay 25 Sync Check Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.4 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-25-sync-check-test.governed-by.ansi-neta-ats | Relay 25 Sync Check Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-25-sync-check-test.governed-by.ansi-neta-mts | Relay 25 Sync Check Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-25-sync-check-test.ieee1547.synchronization | For distributed energy resources that produce a fundamental voltage before connecting, such as synchronous generators, grid-forming inverters and self-excited induction generators, clause 4.10.4 and Table 5 of IEEE 1547-2018 set maximum frequency, voltage and phase angle differences at the moment of paralleling, tiered by aggregate DER rating, and limit the voltage step the paralleling may cause at the point of common coupling; the area electric power system operator may waive the differences where paralleling meets the rapid voltage change limit of clause 7.2. |
| tests.relay-25-sync-check-test.title | The test method is named Relay 25 Sync Check Test. Value: Relay 25 Sync Check Test. |
Relay 27 Undervoltage Test
| Record | Statement |
|---|---|
| tests.relay-27-undervoltage-test.equipment.relay.acceptance | Relay 27 Undervoltage Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.5 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-27-undervoltage-test.equipment.relay.maintenance | Relay 27 Undervoltage Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.5 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-27-undervoltage-test.governed-by.ansi-neta-ats | Relay 27 Undervoltage Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-27-undervoltage-test.governed-by.ansi-neta-mts | Relay 27 Undervoltage Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-27-undervoltage-test.ieee1547-1.type-test | The undervoltage trip type test in clause 5.4.3 of IEEE 1547.1-2020 applies the Annex A.3 step function to voltage: the function is set to the end of its adjustable range closest to nominal with the trip time at its minimum, the source is held just short of the set point on its non-trip side and then stepped past it, the voltage at trip is recorded, and the sequence is repeated for each phase and for all phases together, at the opposite end of the magnitude range, at the maximum trip time and for each undervoltage trip region. |
| tests.relay-27-undervoltage-test.ieee1547-1.type-test-criterion | Clause 5.4.3.4 of IEEE 1547.1-2020 passes the undervoltage trip type test when the equipment under test stops energizing and trips inside the clearing time that IEEE 1547-2018 sets for each range, and when its evaluated adjustment ranges for magnitude and for duration cover the allowable ranges of that standard. |
| tests.relay-27-undervoltage-test.ieee1547.trip-requirements | For distributed energy resources, clause 6.4.1 of IEEE 1547-2018 sets mandatory undervoltage tripping through two functions, UV1 and UV2, each with a default voltage, a default clearing time and a range of allowable settings that depends on the abnormal performance category (Table 11, Table 12 or Table 13, the last as amended by IEEE 1547a-2020). Under clause 4.3 the undervoltage functions respond to whichever applicable voltage is lowest in relation to nominal. |
| tests.relay-27-undervoltage-test.ieee2800.no-mandatory-settings | IEEE 2800-2022 states no undervoltage trip setting for a transmission-connected inverter-based resource plant, as clause 7.2.1 makes explicit; clause 9.3 requires any voltage protection that is applied to permit the voltage ride-through of clause 7.2.2, so the setting against which an undervoltage element is tested is a project value coordinated with the transmission system owner rather than a value from the standard. |
| tests.relay-27-undervoltage-test.title | The test method is named Relay 27 Undervoltage Test. Value: Relay 27 Undervoltage Test. |
Relay 32 Directional Power Test
| Record | Statement |
|---|---|
| tests.relay-32-directional-power-test.equipment.relay.acceptance | Relay 32 Directional Power Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.6 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-32-directional-power-test.equipment.relay.maintenance | Relay 32 Directional Power Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.6 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-32-directional-power-test.governed-by.ansi-neta-ats | Relay 32 Directional Power Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-32-directional-power-test.governed-by.ansi-neta-mts | Relay 32 Directional Power Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-32-directional-power-test.title | The test method is named Relay 32 Directional Power Test. Value: Relay 32 Directional Power Test. |
Relay 40 Loss of Field Test
| Record | Statement |
|---|---|
| tests.relay-40-loss-of-field-test.equipment.relay.acceptance | Relay 40 Loss of Field Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.7 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-40-loss-of-field-test.equipment.relay.maintenance | Relay 40 Loss of Field Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.7 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-40-loss-of-field-test.governed-by.ansi-neta-ats | Relay 40 Loss of Field Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-40-loss-of-field-test.governed-by.ansi-neta-mts | Relay 40 Loss of Field Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-40-loss-of-field-test.title | The test method is named Relay 40 Loss of Field Test. Value: Relay 40 Loss of Field Test. |
Relay 46 Current Balance Test
| Record | Statement |
|---|---|
| tests.relay-46-current-balance-test.equipment.relay.acceptance | Relay 46 Current Balance Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.8 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-46-current-balance-test.equipment.relay.maintenance | Relay 46 Current Balance Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.8 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-46-current-balance-test.governed-by.ansi-neta-ats | Relay 46 Current Balance Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-46-current-balance-test.governed-by.ansi-neta-mts | Relay 46 Current Balance Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-46-current-balance-test.title | The test method is named Relay 46 Current Balance Test. Value: Relay 46 Current Balance Test. |
Relay 46n Negative Sequence Test
| Record | Statement |
|---|---|
| tests.relay-46n-negative-sequence-test.equipment.relay.acceptance | Relay 46n Negative Sequence Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.9 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-46n-negative-sequence-test.equipment.relay.maintenance | Relay 46n Negative Sequence Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.9 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-46n-negative-sequence-test.governed-by.ansi-neta-ats | Relay 46n Negative Sequence Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-46n-negative-sequence-test.governed-by.ansi-neta-mts | Relay 46n Negative Sequence Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-46n-negative-sequence-test.title | The test method is named Relay 46n Negative Sequence Test. Value: Relay 46n Negative Sequence Test. |
Relay 47 Phase Sequence Test
| Record | Statement |
|---|---|
| tests.relay-47-phase-sequence-test.equipment.relay.acceptance | Relay 47 Phase Sequence Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.10 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-47-phase-sequence-test.equipment.relay.maintenance | Relay 47 Phase Sequence Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.10 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-47-phase-sequence-test.governed-by.ansi-neta-ats | Relay 47 Phase Sequence Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-47-phase-sequence-test.governed-by.ansi-neta-mts | Relay 47 Phase Sequence Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-47-phase-sequence-test.title | The test method is named Relay 47 Phase Sequence Test. Value: Relay 47 Phase Sequence Test. |
Relay 49r Thermal Replica Test
| Record | Statement |
|---|---|
| tests.relay-49r-thermal-replica-test.equipment.relay.acceptance | Relay 49r Thermal Replica Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.11 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-49r-thermal-replica-test.equipment.relay.maintenance | Relay 49r Thermal Replica Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.11 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-49r-thermal-replica-test.governed-by.ansi-neta-ats | Relay 49r Thermal Replica Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-49r-thermal-replica-test.governed-by.ansi-neta-mts | Relay 49r Thermal Replica Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-49r-thermal-replica-test.title | The test method is named Relay 49r Thermal Replica Test. Value: Relay 49r Thermal Replica Test. |
Relay 49t Temperature Test
| Record | Statement |
|---|---|
| tests.relay-49t-temperature-test.equipment.relay.acceptance | Relay 49t Temperature Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.12 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-49t-temperature-test.equipment.relay.maintenance | Relay 49t Temperature Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.12 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-49t-temperature-test.governed-by.ansi-neta-ats | Relay 49t Temperature Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-49t-temperature-test.governed-by.ansi-neta-mts | Relay 49t Temperature Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-49t-temperature-test.title | The test method is named Relay 49t Temperature Test. Value: Relay 49t Temperature Test. |
Relay 50 Instantaneous Overcurrent Test
| Record | Statement |
|---|---|
| tests.relay-50-instantaneous-overcurrent-test.equipment.relay.acceptance | Relay 50 Instantaneous Overcurrent Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.13 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-50-instantaneous-overcurrent-test.equipment.relay.maintenance | Relay 50 Instantaneous Overcurrent Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.13 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-50-instantaneous-overcurrent-test.governed-by.ansi-neta-ats | Relay 50 Instantaneous Overcurrent Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-50-instantaneous-overcurrent-test.governed-by.ansi-neta-mts | Relay 50 Instantaneous Overcurrent Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-50-instantaneous-overcurrent-test.title | The test method is named Relay 50 Instantaneous Overcurrent Test. Value: Relay 50 Instantaneous Overcurrent Test. |
Relay 50bf Breaker Failure Test
| Record | Statement |
|---|---|
| tests.relay-50bf-breaker-failure-test.equipment.relay.acceptance | Relay 50bf Breaker Failure Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.14 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-50bf-breaker-failure-test.equipment.relay.maintenance | Relay 50bf Breaker Failure Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.14 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-50bf-breaker-failure-test.governed-by.ansi-neta-ats | Relay 50bf Breaker Failure Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-50bf-breaker-failure-test.governed-by.ansi-neta-mts | Relay 50bf Breaker Failure Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-50bf-breaker-failure-test.title | The test method is named Relay 50bf Breaker Failure Test. Value: Relay 50bf Breaker Failure Test. |
Relay 51 Time Overcurrent Test
| Record | Statement |
|---|---|
| tests.relay-51-time-overcurrent-test.equipment.relay.acceptance | 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. |
| tests.relay-51-time-overcurrent-test.equipment.relay.maintenance | 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. |
| tests.relay-51-time-overcurrent-test.governed-by.ansi-neta-ats | Relay 51 Time Overcurrent Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-51-time-overcurrent-test.governed-by.ansi-neta-mts | Relay 51 Time Overcurrent Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-51-time-overcurrent-test.ieeec37-112.conformance-check | 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. |
| tests.relay-51-time-overcurrent-test.ieeec37-112.expected-time | 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. |
| tests.relay-51-time-overcurrent-test.ieeec37-112.induction-relay-curves | 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. |
| tests.relay-51-time-overcurrent-test.ieeec37-112.reset-check | 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. |
| tests.relay-51-time-overcurrent-test.title | The test method is named Relay 51 Time Overcurrent Test. Value: Relay 51 Time Overcurrent Test. |
Relay 55 Power Factor Test
| Record | Statement |
|---|---|
| tests.relay-55-power-factor-test.equipment.relay.acceptance | Relay 55 Power Factor Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.16 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-55-power-factor-test.equipment.relay.maintenance | Relay 55 Power Factor Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.16 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-55-power-factor-test.governed-by.ansi-neta-ats | Relay 55 Power Factor Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-55-power-factor-test.governed-by.ansi-neta-mts | Relay 55 Power Factor Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-55-power-factor-test.title | The test method is named Relay 55 Power Factor Test. Value: Relay 55 Power Factor Test. |
Relay 59 Overvoltage Test
| Record | Statement |
|---|---|
| tests.relay-59-overvoltage-test.equipment.relay.acceptance | Relay 59 Overvoltage Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.17 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-59-overvoltage-test.equipment.relay.maintenance | Relay 59 Overvoltage Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.17 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-59-overvoltage-test.governed-by.ansi-neta-ats | Relay 59 Overvoltage Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-59-overvoltage-test.governed-by.ansi-neta-mts | Relay 59 Overvoltage Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-59-overvoltage-test.ieee1547-1.type-test | The overvoltage trip type test in clause 5.4.2 of IEEE 1547.1-2020 applies the Annex A.3 step function to voltage: the function is set to the end of its adjustable range closest to nominal with the trip time at its minimum, the source is held just short of the set point on its non-trip side and then stepped past it, the voltage at trip is recorded, and the sequence is repeated per phase, at the opposite end of the range, at the maximum trip time and for each overvoltage trip region. Clause 5.4.2.4 passes the test when the unit trips inside the applicable clearing time of IEEE 1547-2018 and its evaluated adjustment ranges cover the allowable ranges. |
| tests.relay-59-overvoltage-test.ieee1547.trip-requirements | For distributed energy resources, clause 6.4.1 of IEEE 1547-2018 sets mandatory overvoltage tripping through two functions: OV1 with a default and a range of allowable settings per abnormal performance category, and OV2 with a fixed voltage and clearing time common to all categories. Under clause 4.3 the overvoltage functions respond to whichever applicable voltage is highest in relation to nominal. |
| tests.relay-59-overvoltage-test.ieee2800.filtered-quantities | Clause 9.3 of IEEE 2800-2022 requires instantaneous overvoltage protection to operate on filtered quantities, with a minimum measurement window for any element that could trip the whole plant, and to be coordinated with the units' transient overvoltage capability, the plant's surge protection and the ride-through of Table 14. |
| tests.relay-59-overvoltage-test.title | The test method is named Relay 59 Overvoltage Test. Value: Relay 59 Overvoltage Test. |
Relay 60 Voltage Balance Test
| Record | Statement |
|---|---|
| tests.relay-60-voltage-balance-test.equipment.relay.acceptance | Relay 60 Voltage Balance Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.18 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-60-voltage-balance-test.equipment.relay.maintenance | Relay 60 Voltage Balance Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.18 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-60-voltage-balance-test.governed-by.ansi-neta-ats | Relay 60 Voltage Balance Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-60-voltage-balance-test.governed-by.ansi-neta-mts | Relay 60 Voltage Balance Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-60-voltage-balance-test.title | The test method is named Relay 60 Voltage Balance Test. Value: Relay 60 Voltage Balance Test. |
Relay 63 Sudden Pressure Test
| Record | Statement |
|---|---|
| tests.relay-63-sudden-pressure-test.equipment.relay.acceptance | Relay 63 Sudden Pressure Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.19 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-63-sudden-pressure-test.equipment.relay.maintenance | Relay 63 Sudden Pressure Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.19 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-63-sudden-pressure-test.governed-by.ansi-neta-ats | Relay 63 Sudden Pressure Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-63-sudden-pressure-test.governed-by.ansi-neta-mts | Relay 63 Sudden Pressure Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-63-sudden-pressure-test.title | The test method is named Relay 63 Sudden Pressure Test. Value: Relay 63 Sudden Pressure Test. |
Relay 64 Ground Detector Test
| Record | Statement |
|---|---|
| tests.relay-64-ground-detector-test.equipment.relay.acceptance | Relay 64 Ground Detector Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.20 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-64-ground-detector-test.equipment.relay.maintenance | Relay 64 Ground Detector Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.20 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-64-ground-detector-test.governed-by.ansi-neta-ats | Relay 64 Ground Detector Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-64-ground-detector-test.governed-by.ansi-neta-mts | Relay 64 Ground Detector Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-64-ground-detector-test.title | The test method is named Relay 64 Ground Detector Test. Value: Relay 64 Ground Detector Test. |
Relay 67 Directional Overcurrent Test
| Record | Statement |
|---|---|
| tests.relay-67-directional-overcurrent-test.equipment.relay.acceptance | Relay 67 Directional Overcurrent Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.21 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-67-directional-overcurrent-test.equipment.relay.maintenance | Relay 67 Directional Overcurrent Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.21 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-67-directional-overcurrent-test.governed-by.ansi-neta-ats | Relay 67 Directional Overcurrent Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-67-directional-overcurrent-test.governed-by.ansi-neta-mts | Relay 67 Directional Overcurrent Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-67-directional-overcurrent-test.title | The test method is named Relay 67 Directional Overcurrent Test. Value: Relay 67 Directional Overcurrent Test. |
Relay 79 Reclosing Test
| Record | Statement |
|---|---|
| tests.relay-79-reclosing-test.equipment.relay.acceptance | Relay 79 Reclosing Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.22 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-79-reclosing-test.equipment.relay.maintenance | Relay 79 Reclosing Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.22 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-79-reclosing-test.governed-by.ansi-neta-ats | Relay 79 Reclosing Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-79-reclosing-test.governed-by.ansi-neta-mts | Relay 79 Reclosing Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-79-reclosing-test.title | The test method is named Relay 79 Reclosing Test. Value: Relay 79 Reclosing Test. |
Relay 81 Frequency Test
| Record | Statement |
|---|---|
| tests.relay-81-frequency-test.equipment.relay.acceptance | Relay 81 Frequency Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.23 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-81-frequency-test.equipment.relay.maintenance | Relay 81 Frequency Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.23 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-81-frequency-test.governed-by.ansi-neta-ats | Relay 81 Frequency Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-81-frequency-test.governed-by.ansi-neta-mts | Relay 81 Frequency Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-81-frequency-test.ieee1547-1.type-test | The overfrequency and underfrequency trip type tests in clauses 5.5.1 and 5.5.2 of IEEE 1547.1-2020 use the rate-limited step of Annex A.4 with frequency as the parameter under test: other control functions are disabled or set so as not to interfere, frequency droop is set to its widest deadband and maximum droop, the magnitude and duration settings start at the minimum of the adjustable range, the source is moved to a starting point and held, then stepped past the set point and held, and the trip frequency and clearing time are recorded, with repeats at the maximum magnitude, at the maximum duration and for each trip region. |
| tests.relay-81-frequency-test.ieee1547-1.type-test-requirements | Clause 5.5.1.5 of IEEE 1547.1-2020 requires that the rate of change of frequency during the test transitions stay below the category limit of IEEE 1547-2018 Table 21 or within the unit's demonstrated capability, and that the power level be high enough to separate the trip response from the frequency droop response; the pass criterion has the same form as the voltage trip criterion, and tripping inside the regions where IEEE 1547-2018 Annex H.3 allows either ride-through or trip is accepted. |
| tests.relay-81-frequency-test.ieee1547.trip-requirements | For distributed energy resources, clause 6.5.1 and Table 18 of IEEE 1547-2018 set mandatory frequency tripping through two overfrequency functions and two underfrequency functions, with one set of defaults and allowable ranges shared by all three abnormal performance categories; the area electric power system operator specifies the settings after coordinating with the regional reliability coordinator, and the function applies only while the fundamental voltage exceeds a threshold the clause states. |
| tests.relay-81-frequency-test.ieee2800.frequency-protection | Clause 9.1 of IEEE 2800-2022 does not require frequency protection on an inverter-based resource plant; where a frequency element is applied it must allow the frequency ride-through of clause 7.3.2 and be coordinated with the transmission system's underfrequency load shedding. |
| tests.relay-81-frequency-test.ieee2800.rocof-protection | Clause 9.2 of IEEE 2800-2022 does not require rate-of-change-of-frequency protection; where it is applied it must permit the rate-of-change-of-frequency ride-through of clause 7.3.2.3.5, and clause 7.3.2 with its footnote 111 has frequency computed with filtering under clause 4.4 and cautions against letting a frequency measured during a fault decide a trip. |
| tests.relay-81-frequency-test.title | The test method is named Relay 81 Frequency Test. Value: Relay 81 Frequency Test. |
Relay 85 Pilot Wire Monitor Test
| Record | Statement |
|---|---|
| tests.relay-85-pilot-wire-monitor-test.equipment.relay.acceptance | Relay 85 Pilot Wire Monitor Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.24 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-85-pilot-wire-monitor-test.equipment.relay.maintenance | Relay 85 Pilot Wire Monitor Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.24 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-85-pilot-wire-monitor-test.governed-by.ansi-neta-ats | Relay 85 Pilot Wire Monitor Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-85-pilot-wire-monitor-test.governed-by.ansi-neta-mts | Relay 85 Pilot Wire Monitor Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-85-pilot-wire-monitor-test.title | The test method is named Relay 85 Pilot Wire Monitor Test. Value: Relay 85 Pilot Wire Monitor Test. |
Relay 87 Differential Test
| Record | Statement |
|---|---|
| tests.relay-87-differential-test.equipment.relay.acceptance | Relay 87 Differential Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.25 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-87-differential-test.equipment.relay.maintenance | Relay 87 Differential Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.25 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-87-differential-test.governed-by.ansi-neta-ats | Relay 87 Differential Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-87-differential-test.governed-by.ansi-neta-mts | Relay 87 Differential Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-87-differential-test.title | The test method is named Relay 87 Differential Test. Value: Relay 87 Differential Test. |
Relay Time-Delay Timing Test
| Record | Statement |
|---|---|
| tests.relay-2-62-timing-test.equipment.relay.acceptance | Relay Time-Delay Timing Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.1 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-2-62-timing-test.equipment.relay.maintenance | Relay Time-Delay Timing Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.1 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-2-62-timing-test.governed-by.ansi-neta-ats | Relay Time-Delay Timing Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-2-62-timing-test.governed-by.ansi-neta-mts | Relay Time-Delay Timing Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-2-62-timing-test.title | The test method is named Relay Time-Delay Timing Test. Value: Relay Time-Delay Timing Test. |
Relay Volts per Hertz Test
| Record | Statement |
|---|---|
| tests.relay-24-volts-per-hertz-test.equipment.relay.acceptance | Relay Volts per Hertz Test is specified for electromechanical and solid-state protective relays in acceptance testing at clause 7.9.1.B.3.3 of ANSI/NETA ATS-2025. Value: electromechanical and solid-state protective relays. |
| tests.relay-24-volts-per-hertz-test.equipment.relay.maintenance | Relay Volts per Hertz Test is specified for electromechanical and solid-state protective relays in maintenance testing at clause 7.9.1.B.3.3 of ANSI/NETA MTS-2023. Value: electromechanical and solid-state protective relays. |
| tests.relay-24-volts-per-hertz-test.governed-by.ansi-neta-ats | Relay Volts per Hertz Test is addressed in ANSI/NETA ATS-2025. |
| tests.relay-24-volts-per-hertz-test.governed-by.ansi-neta-mts | Relay Volts per Hertz Test is addressed in ANSI/NETA MTS-2023. |
| tests.relay-24-volts-per-hertz-test.title | The test method is named Relay Volts per Hertz Test. Value: Relay Volts per Hertz Test. |
Scada and communication verification
| Record | Statement |
|---|---|
| tests.scada-and-communication-verification.equipment.relay.acceptance | SCADA and Communication Verification is specified for microprocessor-based protective relays in acceptance testing at clause 7.9.2.B.10 of ANSI/NETA ATS-2025. Value: microprocessor-based protective relays. |
| tests.scada-and-communication-verification.equipment.relay.maintenance | SCADA and Communication Verification is specified for microprocessor-based protective relays in maintenance testing at clause 7.9.2.B.5.8 of ANSI/NETA MTS-2023. Value: microprocessor-based protective relays. |
Visual and mechanical inspection
| Record | Statement |
|---|---|
| tests.visual-and-mechanical-inspection.equipment.relay.acceptance | Visual and Mechanical Inspection is specified for low-voltage ground-fault protection systems in acceptance testing at clause 7.14.A of ANSI/NETA ATS-2025. Value: low-voltage ground-fault protection systems. |
| tests.visual-and-mechanical-inspection.equipment.relay.maintenance | Visual and Mechanical Inspection is specified for low-voltage ground-fault protection systems in maintenance testing at clause 7.14.A of ANSI/NETA MTS-2023. Value: low-voltage ground-fault protection systems. |
Zone selective interlocking
| Record | Statement |
|---|---|
| tests.zone-selective-interlocking.equipment.relay.acceptance | Zone Selective Interlocking is specified for low-voltage ground-fault protection systems in acceptance testing at clause 7.14.B.8 of ANSI/NETA ATS-2025. Value: low-voltage ground-fault protection systems. |
| tests.zone-selective-interlocking.equipment.relay.maintenance | Zone Selective Interlocking is specified for low-voltage ground-fault protection systems in maintenance testing at clause 7.14.B of ANSI/NETA MTS-2023. Value: low-voltage ground-fault protection systems. |
Standards
IEEE Standard for Inverse-Time Characteristics Equations for Overcurrent Relays
| Record | Statement |
|---|---|
| std.ieee-c37-112.approved | The IEEE-SA Standards Board approved the 2018 edition of IEEE C37.112 on 2018-12-05. Value: 2018. |
| std.ieee-c37-112.bands-not-tolerance | IEEE C37.112-2018 states in clause 3.4 that its conformance bands are templates for classifying the shape of a curve and are not tolerance bands for timing accuracy or repeatability; the standard gives no timing-accuracy figure, which remains a manufacturer claim for each relay. |
| std.ieee-c37-112.conformance-bands | Clause 3.4 of IEEE C37.112-2018 requires the operate times of a conforming relay to fall inside the band drawn around each standard characteristic in Figures 2 through 4 over a stated range of multiples of pickup; each band lies a fixed proportion above and below the Table 1 time. |
| std.ieee-c37-112.constants-basis | The constants in Table 1 of IEEE C37.112-2018 represent the mean of the induction-relay characteristics analyzed in Annex A, and their digits are chosen so that a change in the last digit moves the relative operate time by only a small fraction over the stated range of multiples of pickup. |
| std.ieee-c37-112.curve-families | Table 1 of IEEE C37.112-2018 lists the trip constants and the optional reset constant of three standard characteristics named moderately inverse, very inverse and extremely inverse; the standard defines no other curve families, so short-time, definite-time and IEC shapes lie outside it. |
| std.ieee-c37-112.definition.time-dial | In IEEE C37.112-2018 the time dial is the relay setting that fixes the integral quantity at which the relay operates, and so sets the time scale of the whole operate curve. |
| std.ieee-c37-112.designation | IEEE C37.112-2018 is the designation of the document titled IEEE Standard for Inverse-Time Characteristics Equations for Overcurrent Relays. Value: IEEE C37.112-2018. |
| std.ieee-c37-112.dynamic-conformance | Clause 3.4 of IEEE C37.112-2018 makes dynamic behavior part of conformance: a microprocessor relay conforms only when it implements the integral equation with the trip-equation time rather than a static curve fit, so that coordination with induction relays holds while the current changes. |
| std.ieee-c37-112.equation.dynamic-form | The dynamic equation of clause 3.2 of IEEE C37.112-2018 integrates the reciprocal of the trip-equation time over the current history and declares operation when the integral reaches unity, which lets the characteristic follow a changing fault current. |
| std.ieee-c37-112.equation.operate-form | The trip equation of clause 3.2 of IEEE C37.112-2018 expresses operate time as the time dial multiplied by the sum of two terms: an inverse term, in which a curve constant is divided by the multiple of pickup raised to a curve exponent less unity, and a definite-time constant that represents the core saturation component of an induction relay. |
| std.ieee-c37-112.equation.reset-form | The optional reset equation of clause 3.2 of IEEE C37.112-2018 applies while the current is below pickup and gives a negative time, representing the travel of an induction disk back toward its reset position, derived from a reset constant defined as the reset time at zero current. |
| std.ieee-c37-112.iec-relationship | The trip equation of IEEE C37.112-2018 has the same form as the inverse-time characteristic of IEC 60255-151:2009 with a definite-time constant added, the added term modeling the saturation of an induction relay core. |
| std.ieee-c37-112.rationale.fuse-coordination | Clause 3.1 of IEEE C37.112-2018, with Figure 1, presents the close coordination between the extremely inverse characteristic and a high-voltage fuse as the rationale for inverse characteristics in the grounded four-wire distribution practice of North America. |
| std.ieee-c37-112.revision-of | IEEE C37.112-2018 is a full revision of IEEE C37.112-1996. Value: 1996. |
| std.ieee-c37-112.scope | IEEE C37.112-2018 supplies analytic equations for the typical inverse-time overcurrent characteristic shapes so that microprocessor and computer based relays can reproduce the curves of induction-disk relays and coordinate with them. The document covers the equation forms, the constants of three standard characteristics and the conformance criteria for a relay that claims one of those characteristics. |
| std.ieee-c37-112.sponsor | The sponsor of IEEE C37.112-2018 is the Power System Relaying Committee of the IEEE Power and Energy Society. |
| std.ieee-c37-112.structure.annex-a | Annex A of IEEE C37.112-2018 is informative; it derives the trip and reset equations from the dynamics of an induction disk and tabulates measured constants for two induction relay models in Tables A.1 and A.2. |
| std.ieee-c37-112.structure.definitions | Clause 2 of IEEE C37.112-2018 defines the terms inverse-time overcurrent relay, reset characteristic, reset and time dial. |
| std.ieee-c37-112.structure.equations | Clause 3.2 of IEEE C37.112-2018 states three equations: a trip equation for current above pickup, an optional reset equation for current below pickup, and an integral form that governs operation when the input current varies with time. |
| std.ieee-c37-112.time-dial-scaling | Clause 3.3 of IEEE C37.112-2018 states that the time dial scales the two trip constants and the reset constant together, each in direct proportion to the dial setting, and that a microprocessor relay holds the ratio of the two trip constants fixed whereas an induction relay may let it drift somewhat. |
| std.ieee-c37-112.title | The licensed copy of IEEE C37.112-2018 carries the full title IEEE Standard for Inverse-Time Characteristics Equations for Overcurrent Relays. Value: IEEE Standard for Inverse-Time Characteristics Equations for Overcurrent Relays. |