| Brand | ROCKWILL |
| Model NO. | Customization 15kV 30kV 33kV 34.5kV 36kV Three Phase Neutral Grounding/earthing Transformer direct supply |
| Rated voltage | 36kV |
| Rated normal current | 3000A |
| Rated frequency | 50/60Hz |
| Series | JDS |
Description
As a pioneer and the first dedicated original equipment manufacturer (OEM) in China's earthing transformer industry, we have laid the original benchmark for the industry's development with our profound technical strength accumulated through decades of intensive cultivation. From the independent R&D of core technologies to large-scale mass production, we have built a full-process independently controllable system. Relying on stable and leading product performance and unparalleled reliability, we have become a preferred partner in the field of power grid construction.
This grounding transformer, suitable for systems up to 36kV, is a specialized electrical device. It creates an artificial neutral point in power grids, playing a crucial role in grounding protection. By effectively handling single - phase ground faults, it ensures the stable operation of medium - voltage power systems, whether in urban distribution networks or industrial power setups.
Feature
Voltage Adaptability：Designed for up to 36kV systems, it matches the common voltage levels of medium - voltage power grids, ensuring wide - ranging applicability.
Fault Handling：Efficiently suppresses arc - grounding overvoltages during single - phase ground faults. It helps reduce ground fault currents, minimizing damage to power grid equipment and enhancing system reliability.
Robust Construction：Built with high - quality materials like premium magnetic cores and durable windings. The enclosure is sturdy, resisting harsh environmental factors such as moisture and dust, ensuring long - term stable performance.
Safety Enhancement：Provides a reliable neutral grounding solution, preventing abnormal voltage fluctuations and equipment insulation damage, thus safeguarding the safety of the entire power grid and connected electrical devices.
Main technical parameter
Some of these earthing transformers cover voltage levels including：3.3kV / 6kV / 11kV / 15kV / 20kV / 22kV / 30kV / 33kV / 34.5kV / 36kV / 44kV / 66kV / 88kV / 110kV / 132kV / 145kV / 150kV / 220kV / 275kV / 330kV / 400kV, etc. The current withstand time ranges from 1s, 2s, 3s, 5s, 6s, 8s, 9s, 10s, 30s, 60s, 1hour to 2hours, and customization is available.
Types |
oil-immersed [ZN(Zig-zag), ZNyn] |
Voltage |
Up to 36kV |
Current |
Up to 3000A |
Duty (seconds) |
10 / 30 / 60 or others |
Cooling method |
ONAN, ONAF; AN, AF |
Frequency |
50 / 60Hz |
Installation |
Indoor / Outdoor |
Ambient Temperature |
-25°C to 40°C |
Standards |
IEC 60076-6 IEC 60076-1 |
Enclosure Options |
Transformer cabinets for any IP degreess with: -CT -VT -Isolation switch |
Note: This parameter table is for reference. We can offer customize production tailored to client specifications.
Scope of Application
Suitable for scenarios with varying capacities and voltage levels.
35kV and Above Distribution Networks: Transformer windings typically adopt a star (Y) connection with an accessible neutral point, eliminating the need for grounding transformers.
6kV and 10kV Distribution Networks: Transformer windings mostly use delta (Δ) connections without accessible neutral points, requiring grounding transformers to provide a neutral point.
Special Scenarios: When system unbalanced voltage is high, Z-type transformers can meet measurement requirements through balanced design of their three-phase windings. When system unbalanced voltage is low (e.g., fully cable-based networks), the neutral point of Z-type transformers must generate an unbalanced voltage of 30-70V to satisfy measurement criteria.
Purpose and Function: Provides a return path for fault currents, ensuring safety and stability during ground faults.
Operating Principle During Faults: During a ground fault, fault current flows through the transformer’s neutral point. The counteracting magnetic flux generated by reverse current neutralizes impedance.
Voltage and Current Ratings: Rated voltage matches the system’s line voltage. Capable of withstanding maximum fault currents for up to 30 seconds.
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.
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.
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.
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
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.
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