Relay
The acceptance test for protective relays - whether electromechanical or solid-state - is a multi-part electrical and functional verification that confirms the relay is sound, correctly connected, and ready to detect faults and signal a breaker trip when called upon. The test battery includes identification of the relay manufacturer, model, type, and associated ratio equipment (such as a current transformer ratio); insulation-resistance measurement between the relay circuits and the relay frame to screen for contamination or moisture ingress; and a functional test that confirms the relay control contacts operate correctly and that connected breaker-trip circuits respond as designed. NETA ATS-2025 Section 7.9.1 lays out the acceptance scope for both relay styles.
A protective relay is a decision-making device: it samples voltage or current from the power system, compares those values against a set of rules (pickup thresholds, time delays, directional criteria), and when conditions match the alarm case, it closes a contact that tells a breaker to trip. If the relay has a high-resistance fault to its frame, a mis-connected input, or a stuck contact, it may fail to trip when the system needs it to, or it may trip falsely, either of which undermines the reliability and safety of the switchgear and the broader network. A pre-energization acceptance test rules out manufacturing defects, shipping damage, loose terminations, and control-circuit open-circuits before the relay is trusted to protect a live circuit.
Acceptance: the test is run before a new or reconditioned relay is first placed in service, as part of the standard switchgear or protection-scheme commissioning sequence. The test may be run at the factory (as a quality check before shipment), in the field on a bench before the relay is mounted, or in the field after the relay is installed but before the breaker and instrument transformers are energized, provided the relay itself is isolated from live circuits.
With the relay de-energized and isolated per the job's safety plan, the technician first identifies and records the relay manufacturer, model, type (electromechanical or solid-state), and any related equipment designations such as a current-transformer ratio or potential-transformer ratio. Next, an insulation-resistance ohmmeter (typically a handheld 500 V or 1000 V megohmmeter) is connected between each relay circuit and the relay frame to measure leakage resistance; the measurement is taken after a timed settling period to allow any absorbed charge to stabilize. Finally, the control contacts are tested by injecting a low-level signal (simulating fault detection) into the relay's trip circuit and confirming that the relay contact closes and the connected breaker-trip solenoid, bell, or test button responds correctly, demonstrating the trip signal path from relay contact to breaker coil.
The relay identification (manufacturer, model, style number, type, and transformer ratios if applicable), the insulation-resistance readings in megohms between each circuit and ground, the date and time of test, ambient temperature, the megohmmeter model and calibration status, and the results of the control-verification and trip-circuit tests (whether each contact operated correctly, whether the breaker responded or the trip signal was confirmed downstream).
NETA ATS-2025 Section 7.9.1.B.1 requires an insulation-resistance measurement between each relay circuit and the relay frame, but the standard does not publish its own numeric minimum for electromechanical relays - acceptance is governed by the relay manufacturer's published data, and any reading below the manufacturer's recommended value calls for cleaning, drying, or replacement before the relay is energized; solid-state relays may require a manufacturer-specified insulation-resistance procedure in place of the standard megohmmeter test. NETA ATS-2025 Section 7.9.1.B.4 requires that control contacts and breaker-trip circuits respond correctly to the test signal without stalling or failing to operate, again evaluated against the relay manufacturer's design data and the owner-supplied coordination study or setting sheet rather than a fixed NETA value. The relay is accepted for service only if all identification fields are correctly recorded, insulation resistance meets the manufacturer's recommendation in every circuit, protection-element calibration matches the specified setting points, and all control and trip functions perform their intended action on command. See the purchased standard for the complete acceptance procedure and any relay-type-specific exceptions.
Reference pages for the tests this form carries.
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