Three Phase Neutral Grounding Transformer Supplier 15kV-36kV

The optional 0.4 kV auxiliary winding enables dual‑function operation of the earthing transformer.

Besides its core duty of creating artificial neutral‑point for MV‑network earth‑fault protection, this winding can output low‑voltage power and act as a station‑service transformer to supply local auxiliary loads inside substation sites.

Its maximum available capacity is up to 500 kVA. Please note this auxiliary winding is for station‑service supply only and cannot take priority over the earthing‑protection function under earth‑fault conditions.

If you require this dual‑use function, specify auxiliary‑winding kVA rating during technical clarification phase.

Every Rockwill earthing transformer is manufactured and tested complying with IEC 60076‑6, IEC 60076‑1, IEC 60071‑1 and ISO 9001 quality‑system requirements.

Before shipment, each unit completes a full set of routine factory tests including winding‑resistance measurement, ratio‑and‑vector‑group verification, zero‑sequence‑impedance measurement, no‑load and load‑loss test, dielectric withstand tests and sealing‑leakage inspection.

Upon customer request, we can provide complete type‑test reports covering short‑time fault‑current withstand, temperature‑rise test and insulation‑co‑ordinatio

Yes, the JDS series supports both indoor and outdoor installation. For outdoor deployment, the fully‑sealed mineral‑oil tank structure works well under all‑weather conditions, and we can supply IP‑rated protective enclosures, external CT/VT and isolating‑switch assemblies as factory‑integrated packages.

If installed indoors, users must guarantee sufficient ventilation for heat dissipation of radiators and comply with local fire‑safety rules for oil‑filled electrical equipment.

Standard environmental baseline covers altitude ≤ 1000 m, pollution class II, ambient temperature from -25 °C to +40 °C. For high‑altitude, heavy salt‑fog coastal or heavily‑polluted sites, please notify us in advance so we can upgrade insulation, creepage distance, anti‑corrosion coating and perform necessary thermal derating design.

Absolutely. The JDS‑series zig‑zag earthing transformer is purpose‑built to create an artificial neutral point for delta‑connected or ungrounded medium‑voltage grids.

Its externally‑brought‑out neutral terminal can be connected either to a Petersen coil for resonant‑earthing schemes or to neutral‑grounding resistors (NGR) for resistive‑earthing networks.

When placing an order, please share your system earthing philosophy, target fault‑current magnitude and required short‑time withstand duration. Our engineering team will tune zero‑sequence impedance, rated neutral‑current and short‑time rating to perfectly match your selected neutral‑earthing device.

The specially optimized ZNyn11 zigzag winding structure features low and controllable zero-sequence impedance. When a single-phase earth fault occurs, it can form a smooth fault current loop. This characteristic ensures the relay protection device can detect faults sensitively and act reliably.

Compared with using ordinary power transformers for grounding purposes, this dedicated winding avoids uncontrolled zero-sequence current, extra stray loss and unexpected local overheating risks under earth fault conditions.