Overview

As a trailblazer and the first dedicated original manufacturer in China’s earthing transformer sector, decades of focused technical advancement have endowed us with robust capabilities and even laid the foundational standards for industry development. Spanning from breakthroughs in core R&D to large-scale production and delivery, we’ve built an end-to-end independent ecosystem. Boasting leading and stable product performance paired with exceptional reliability, we stand as a trusted partner for power grid construction projects.

Rockwill 35kV 36kV 44kV 66kV Three Phase Cast Resin Dry Type Zigzag (Z-Type) Grounding Transformer  provide a reliable artificial neutral grounding solution for power systems where the neutral point is unavailable, such as delta-connected or ungrounded star systems. These specialized transformers create a stable neutral point for connecting arc suppression coils (Petersen coils) or neutral grounding resistors, ensuring safe and effective system grounding.

Additionally, Rockwill grounding transformers can be equipped with a secondary winding to supply auxiliary power, offering a cost-effective alternative to separate station transformers.

Key attributes

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.

Key Applications

• Substations and distribution networks (35kV and below)

• Industrial power systems requiring a neutral grounding point

• Renewable energy plants (wind/solar farms) with ungrounded sources

Main Technical Specifications

• Rated Capacity: 100kVA to 5500kVA

• Rated Voltage: Up to 35kV

• Insulation Class: Class F (compliant with IEC 60076)

• Connection Type: Zigzag (Z-Type) for optimal zero-sequence performance

• Zero-Sequence Impedance: Low impedance (~10Ω) for efficient fault current handling

Key Features & Benefits

• Advanced Zigzag Winding Design – Unlike conventional transformers, Rockwill’s Z-Type configuration ensures zero-sequence flux circulates within the core, minimizing impedance and enhancing grounding performance.

•  Full-Capacity Arc Suppression Support – Compatible with 90-100% rated capacity arc suppression coils, far exceeding the 20% limit of standard transformers.

• Dual-Purpose Functionality – Optional secondary winding allows the transformer to supply station power, reducing the need for additional equipment.

•  Dry-Type, Cast Resin Construction – Maintenance-free, flame-resistant, and suitable for harsh environments.

• High Efficiency & Reliability – Engineered for stable operation under fault conditions, preventing magnetic saturation.

•  IEC 60076 Compliant – Manufactured to international standards for global reliability.

Why Choose Rockwill?

Rockwill grounding transformers deliver superior performance, safety, and cost savings by combining neutral grounding and auxiliary power supply in a single unit. Their optimized design ensures enhanced system protection, reduced downtime, and lower installation costs—making them the ideal choice for modern power systems.