| Brand | ROCKWILL |
| Model NO. | 35kV 36kV 44kV 66kV Three Phase Cast Resin Dry Type Zigzag (Z-Type) Grounding Transformer |
| Rated capacity | 400kVA |
| Phases | Three phase |
| Series | DKSC |
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.
application |
power |
coil structure |
toroidal |
place of origin |
china |
model number |
DKSC10-400/35 |
off-load loss |
1500w |
neutral point current |
20A |
phase |
three |
coil number |
autotransformer |
brand name |
rockwill |
rated capacity |
400kVA |
zero sequence impedance (zn) |
170 |
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
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
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.
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.
Continuous neutral current refers to the small current flowing through the neutral line of the earthing/grounding transformer due to factors such as three-phase load imbalance and harmonics during normal system operation, which is not a fault current. Its common range is 100A-400A, and this parameter is an important indicator for operation and maintenance monitoring: ① The three-phase balance of the system can be judged by monitoring the continuous neutral current. If the current suddenly increases, it may be a signal of load imbalance or equipment abnormality; ② Its design value directly affects the iron loss and temperature rise of the earthing/grounding transformer. During selection, it must be determined in combination with the historical unbalanced data of the system to avoid equipment aging caused by long-term overcurrent.
Application scenarios are highly bound to voltage levels and insulation types, with specific matches as follows:
