A dry-type reactor acceptance test is a field protocol that verifies a shunt or current-limiting reactor has the winding and insulation condition its factory test report claims, before it is energized. It records the identification (manufacturer, model and catalog number, serial number, reactor type as shunt or current-limiting, kVAR rating, rated voltage and current, basic impulse level, phase configuration, insulation class, temperature rise, and equipment designation) with the as-found and as-left tap positions. The inspection covers nameplate data against the drawings, physical and mechanical condition, anchorage, alignment and grounding, cleanliness, insulation power-factor testing of all windings, bolted-connection tightness, tap connections as specified, and a thermographic survey. The electrical work covers bolted-connection resistance, winding-to-ground insulation resistance with temperature correction, winding resistance compared against the factory values, an optional dielectric withstand test winding to ground, and optional insulation power factor corrected to the reference temperature. On maintenance visits an online partial-discharge survey may be added under the maintenance edition of the standard. NETA ATS-2025 section 7.20.3.1 lists this as the standard acceptance sequence.
A reactor is a deliberately inductive winding, and that makes its acceptance test a comparison exercise rather than a search for absolute values. Winding resistance is the most direct evidence of a manufacturing or shipping defect: a turn-to-turn short or a damaged lead moves the resistance away from the factory value, and because a reactor has no secondary to check against, the factory number is the reference. Insulation resistance and power factor answer the dielectric question, which on a dry-type unit is largely about contamination and moisture on accessible surfaces rather than about a liquid. The tap connection check exists because a reactor is often supplied with taps to set the reactance, and a unit energized on the wrong tap does not fail, it simply does the wrong job: a current-limiting reactor set too low does not limit fault current to the value the study assumed.
Acceptance: after installation and before the reactor is energized, as part of the standard acceptance sequence, with the factory test report in hand so the winding resistance comparison can be made on site. The same form carries a maintenance service type, since bolted-connection resistance, insulation resistance, winding resistance, and power factor are repeated on a periodic basis, and the maintenance edition also offers an online partial-discharge survey for units in service. Insulation resistance is taken before any dielectric withstand test, and tap positions are recorded as found and as left because a tap change is the one adjustment most likely to be made and forgotten.
With the reactor de-energized, isolated, and grounded per site safety procedures, the identification data and the as-found tap position are recorded, and the inspection is worked through: condition, anchorage, alignment and grounding, cleanliness, the tap connections against the specification, and bolted connections verified with a calibrated torque wrench or by resistance measurement. Bolted-connection resistance is measured phase by phase with a low-resistance ohmmeter. Winding-to-ground insulation resistance is then measured on each winding at the test voltage the standard's table assigns to the reactor's rating and corrected to a common temperature. Winding resistance is measured on each winding and set against the factory value so the deviation can be calculated. Where a dielectric withstand test is in scope, an ac or dc voltage is applied winding to ground for one minute at a level referenced to the factory test voltage, and the unit is watched for distress. Where power factor is in scope, it is measured on each winding at the stated test voltage and corrected to the reference temperature. The as-left tap position, ambient temperature, relative humidity, and the test equipment with its calibration due date are recorded with the results.
The identification (manufacturer, model and catalog number, serial number, reactor type, kVAR rating, rated voltage and current, basic impulse level, phase, insulation class, temperature rise, and equipment designation); the as-found and as-left tap positions; the result of each visual and mechanical item, including the tap connection check and the thermographic survey; bolted-connection resistance per phase; the insulation-resistance test voltage and the winding-to-ground readings as measured and temperature corrected; the measured and factory winding resistance per winding with the deviation; the dielectric withstand test type, applied voltage, duration, and per-winding result where performed; the power-factor test voltage with the measured and temperature-corrected values per winding; the partial-discharge survey result and notes on a maintenance visit; and the ambient temperature, relative humidity, test equipment with calibration due date, comments, and deficiencies.
Bolted-connection resistance readings are compared with similar connections and a reading well above the lowest is investigated. Winding-to-ground insulation resistance must meet the manufacturer's published data or, in its absence, the minimum the standard's insulation-resistance table gives for the reactor's nominal rating, with lower values investigated. Winding resistance must stay within the published percentage of the factory results, which is the tightest criterion in this sequence and the reason the factory report has to be on site. The dielectric withstand test has its applied voltage expressed as a fraction of the factory test voltage, ac and dc treated differently, and passes only if no distress or insulation failure appears through the full application time. Power factor corrected to the reference temperature is judged against the manufacturer's published maximum; the standard's power-factor table is scoped to liquid-filled apparatus and has no dry-type column, so for a dry-type reactor the manufacturer's data is the operative limit. Tap connections must be as specified, bolt torque follows the manufacturer's data with the standard's torque table used in its absence, and the thermographic survey is judged under its own section. On maintenance, partial-discharge results follow the manufacturer's data or the maintenance standard's survey table, read against established background levels. See the purchased NETA standard for the table values and the unit's factory test report for its reference values.
UltraDb references ASTM, ANSI, IEEE, and NETA standards descriptively, to identify the published methods its forms are built from. UltraDb and Entigy Solutions are not affiliated with, endorsed by, certified by, or licensed by NETA, ASTM, ANSI, IEEE, or Megger. Standard names and section numbers are the property of their respective organizations. Always test to the edition your contract specifies.