| Brand | ROCKWILL |
| Series | JDS |
| Rated voltage | 24 kV |
| Rated neutral current | Up to 3000 A |
| Rated frequency | 50 / 60 Hz |
Description
As a pioneer and the first dedicated original manufacturer in China's earthing transformer industry, decades of in-depth technical cultivation have enabled us to accumulate strong strength and even establish the original standards for industry development. From breakthroughs in core technology R&D to large-scale mass production and delivery, we have built an end-to-end independent ecosystem. Leveraging leading and stable product performance as well as extremely reliable quality, we have become a trusted choice in the field of power grid construction.
This three - phase 11kV/22kV grounding transformer is tailor - made for medium - voltage power grids. By creating an artificial neutral point, it accurately achieves the grounding protection function and is suitable for various distribution system scenarios. When facing single - phase grounding faults, it can effectively handle them, building a solid defense for the stable operation of urban power grids and industrial power facilities, and ensuring the reliable power supply of the power system.
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.
Number of phases |
Three rows |
Output voltage |
400V |
Frequency |
50/60Hz |
Input voltage |
11kV 20kV 22kV 30kV 33KV 34.5kV 36kV |
High pressure rating |
11KV/22KV/33KV |
Low pressure rating |
0.4 KV |
Number of coils |
Three Windings |
Link category |
Dyn11 Yyno |
Coil structure |
toroidal |
Certification |
IEC60076 |
Insulation level: |
Dyn11 Yyno |
Application |
Industrial Equipments |
Standard |
IEC60076 |
Use |
Power transformer |
Class |
Oil - Immersed Transformer |
Product name |
Grounding Transformer |
Application Environment Description
Neutral Grounding Systems：Suitable for ungrounded, resistance-grounded, or arc-suppression-coil grounded medium-voltage distribution networks. Limits fault current and improves power supply reliability.
Harsh Physical Environments：IP54/IP56 protection rating, resistant to salt mist and dust. Suitable for altitudes up to 3000m and ambient temperatures from -25°C to +45°C.
Space-Constrained Locations：Compact dry-type design suitable for confined spaces such as underground substations, data centers, and ship engine rooms.
New Energy and Industrial Applications：Neutral grounding protection for systems including wind/solar power plants, rail transit, mining facilities, and oil platforms.
Special Electrical Environments：Compatible with systems containing harmonic pollution, frequent start-stop loads, and smart grids requiring coordination with protection devices.
Fault withstand time is the maximum duration an earthing transformer can endure fault-current thermal and mechanical stresses under rated short-time capacity, with standard durations of 10s, 30s, 60s, or 1 hour per IEEE 32/IEC 60076‑5. Selection must ensure withstand time ≥ protection clearing time plus redundancy—e.g., a 15‑second relay trip requires a 30‑second withstand rating to prevent damage.
Rockwill Zig-zag (ZN connection) earthing transformers compete with global leading brands including Hitachi Energy, Schneider Electric and GE Vernova in technology, configuration and package delivery.
Key difference: Rockwill customizes zero-sequence impedance and short-time fault current precisely according to system capacitive current, supporting standalone unit or complete neutral earthing package. Customers select configurations only for actual requirements without overpaying for redundant performance.
Rockwill’s economical earthing transformer variant. It retains the core Zig-zag ZN winding structure to create artificial neutral point, with basic temperature monitoring as standard.
Cost optimization can be achieved via the following downgrade options:
The solution cuts unnecessary features while guaranteeing required neutral earthing function and compliance to reduce capital expenditure.
Rockwill provides industry-leading warranty for earthing transformers:
10-year+ full-unit warranty covering core, ZN windings, tank/enclosure and sealing components.
We offer free repair or replacement of defective parts for failures caused by material or manufacturing defects within warranty period. Damage caused by human error, system overvoltage or operation exceeding the nameplate short-time fault duty is excluded. Terms are clear with no hidden clauses.
This guarantee is backed by years of design and field operation experience for neutral earthing packages. Most competitors only offer standard 1–2 year warranty. Earthing transformers operate under short-time fault duty. Rockwill’s extended warranty demonstrates confidence in winding insulation and structural reliability.
Yes. Rockwill support full OEM / ODM cooperation. We select partners rigorously, prioritizing system integrators with power engineering capability, local delivery and after-sales service. Ideal partners are not only distributors, but also capable of local technical support to jointly deploy neutral earthing packages.
| Item | Rockwill Zig-zag Earthing Transformer | Ordinary 3-phase transformer repurposed for neutral grounding |
|---|---|---|
| Winding | Dedicated Zig-zag ZN winding, high impedance for positive/negative sequence, low & stable zero-sequence impedance; zero-sequence flux closes within core limbs | Standard YNd/YNy winding. Zero-sequence flux travels through tank/clamp, creating extra losses and uncontrolled Z0 |
| Purpose | Designed to create artificial neutral point for short-time single-phase earth fault duty | Designed for power transformation, not earth-fault duty |
| Fault withstand | Custom short-time fault current & duration (typical 10s/30s/60s) per project | Limited zero-sequence loading. Engineering experience shows the matched Petersen coil capacity is generally limited to 20% of transformer rating, with risk of local overheating |
| Package | Native compatible with arc suppression coil / neutral earthing resistor cabinet | Requires heavy modification for neutral earthing, high engineering risk |
| Standard | IEC 60076-6, type test verified for earthing duty | General power transformer standard, no dedicated earth-fault verification |
Summary: Repurposed ordinary three-phase transformers are NOT recommended for MV distribution neutral earthing. Rockwill Zig-zag earthing transformer is purpose-built for short-time single-phase earth faults with stable zero-sequence characteristics, offering reliable artificial neutral point for distribution networks.
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