The acceptance test for a direct-current system charger is a field inspection and functional measurement suite that verifies the charger meets its nameplate output ratings and design parameters before it is placed into service to supply battery banks or other DC equipment. NETA ATS-2025 7.18.2 requires verification of the charger's identity, input phase configuration (single or three-phase AC input), charger type, and equipment designation, followed by measurement of the output voltage under no-load and full-load conditions, verification of the current-limit setting and its measured response, and confirmation that the unit's regulation and protective functions operate as designed. The test covers both the AC side (input supply adequacy and phase balance) and the DC side (output voltage stability, current capacity, and regulation).
A charger that supplies a critical battery bank or DC control system must deliver stable, regulated voltage within specification from the moment the bank is first placed under charge, and must not allow output current to exceed the setting intended to protect the battery and the charger itself. Testing before energization confirms that the charger's internal components (transformer, rectifier, filter, regulation circuits, and current-limit protection) are wired correctly, not damaged by manufacturing or shipping, and responding to control inputs as the design requires. A charger that cannot hold its output voltage or whose current limit is stuck open, stuck closed, or misadjusted will either overcharge the battery (shortening its life or causing a thermal runaway in certain chemistries) or fail to charge it, and both failures go undetected if testing is deferred until the bank is already in service.
Acceptance: run before a new or reconditioned charger is first energized and connected to its battery bank or load, as part of the initial commissioning sequence and before the unit is left unattended in automatic charge mode. Maintenance: periodic re-verification is not a NETA standard requirement for chargers already in service, but field testing may be repeated if the charger's output drifts, the current-limit function fails to respond, or the battery is observed charging more slowly or faster than normal.
With the charger de-energized and isolated, the input supply voltage and phase configuration (single or three-phase) are verified to match the charger's nameplate. Once supply is confirmed adequate, the charger is energized under no load and the output voltage is measured at the charger's terminals; the regulation (the change in output voltage from no load to full load) is then observed by applying a resistive or battery load equal to the charger's rated full-load current and re-measuring the output voltage. The current-limit adjustment (if present as a user-accessible control) is set to its intended value, the limit function is triggered by attempting to draw more current than the limit setting, and the response (a voltage drop, a current plateau, or an alarm) is observed and compared against the design expectation. All measurements are made with calibrated DC volt and ammeter equipment.
For each charger tested: the equipment designation, manufacturer, model / catalog number, input phase configuration (1 or 3 phase), charger type (constant-voltage, constant-current, or two-stage), the measured no-load output voltage, the rated full-load output current in amperes and the measured full-load output current, the current-limit setting in amperes and the measured current limit in amperes, the output voltage at full load, the calculated regulation percentage or absolute voltage change, any ambient temperature or supply condition anomalies, and the test-instrument identification (make, model, serial, calibration due date). A pass / fail determination for each function tested is recorded alongside the raw data so commissioning can proceed or service actions triggered.
NETA ATS-2025 section 7.18.2 establishes that the charger's output voltage under full load must remain stable and within the range the charger's design or the battery manufacturer specifies; a deviation outside that band is grounds for investigating the charger's regulation circuit or transformer tap before the unit is left in service. The current-limit function must respond to an overload attempt by limiting output current to the set threshold or less, halting further charging until the load is reduced; failure to limit indicates a stuck or miscalibrated protective circuit. The full-load output current must match the charger's rated capacity within the tolerance the standard establishes for the equipment class and input supply voltage, confirming that transformer and rectifier sizing are correct and that loading has not degraded performance. See the purchased standard for the complete acceptance criteria and any equipment-type-specific limits.
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