35kV 36kV 44kV 66kV Three Phase Cast Resin Dry Type Zigzag (Z-Type) Grounding Transformer
Key attributes
| 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 |
Product descriptions from the supplier
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.
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
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.
Application scenarios are highly bound to voltage levels and insulation types, with specific matches as follows:
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Medium voltage (3.3kV-44kV): Dry-type products are mostly used in industrial plant areas (such as 6kV chemical workshops) and urban distribution stations (10kV indoor stations); oil-immersed products are used in outdoor rural power grids and mining area distribution networks (33kV outdoor stations), focusing on solving the protection problem of single-phase ground faults in distribution networks.
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High voltage (66kV-150kV): Mainly oil-immersed type (ONAF cooling), used in regional transmission substations (such as 110kV county-level substations) and main power supply points of large industrial parks to ensure rapid isolation during faults and guarantee power supply reliability.
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Extra-high voltage (220kV-400kV+): All are large-capacity oil-immersed products (5MVA and above), used in cross-regional transmission trunk networks and provincial power grid hub substations. They work synergistically with arresters and grounding resistors to protect the insulation safety of core equipment such as converter valves and transformers.
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.
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Related Knowledges
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Protection Logic Improvement and Engineering Application of Grounding Transformers in Rail Transit Power Supply Systems1. System Configuration and Operating ConditionsThe main transformers at Zhengzhou Rail Transit’s Convention & Exhibition Center Main Substation and Municipal Stadium Main Substation adopt a star/delta winding connection with a non-grounded neutral point operation mode. On the 35 kV bus side, a Zigzag grounding transformer is used, connected to ground through a low-value resistor, and also supplies station service loads. When a single-phase ground short-circuit fault occurs on a line, a pathEcho12/04/2025
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