| Brand | ROCKWILL |
| Model NO. | 6-35KV 33KV oil-immersed neutral grounding resistance to transformer (earthing transfoemer) |
| Rated voltage | 33kV |
| Rated frequency | 50/60Hz |
| Rated capacity | 800kVA |
| Series | JDS |
Product Introduction
With decades of focused expertise in the field of grounding transformers, we have built end-to-end independent capabilities—from core R&D to scaled mass production—through sustained technological depth. Leveraging industry-leading product performance and long-term reliability, we have established the technical benchmark in this field domestically, becoming a core force driving the advancement of grid safety.
Our 6-35kV (including 33kV) oil-immersed neutral grounding resistance transformers, also known as earthing transformers, are designed for medium-voltage grids. Using oil cooling technology, they safely dissipate heat. By creating a neutral point connection with a grounding resistance, these transformers quickly detect and limit ground faults. Ideal for enhancing grid reliability, they offer robust protection against electrical failures, ensuring stable power supply for industrial and commercial applications.
Performance Advantages
Energy-Efficient & Eco-Friendly: Low-loss, low-noise, and high-efficiency design reduces energy consumption and environmental impact.
Fully Sealed & Maintenance-Free: No oil storage tank required. Corrugated tank design automatically adjusts for oil volume changes, eliminating leakage risks.
Extended Lifespan: Sealed structure isolates oil from air, slowing degradation and insulation aging. Reduces maintenance costs and extends operational life.
Main technical specifications
The following table details the key technical specifications of the product, comprehensively covering electrical performance, mechanical characteristics, and dimensional parameters to provide a clear reference for technical selection and application scenarios.
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.
Parameter |
Specification |
Use |
Power |
Number of phases |
Three |
Coil structure |
Toroidal transformers |
Number of coils |
Autotransformers |
Model |
SJD - 800/33 |
Authentication |
ISO9001 |
Material |
Copper/aluminum/customized |
Frequency |
50Hz/60Hz |
Application |
Industrial power supplies |
Standard |
IEC60076 |
Rated capacity |
30-3000kva/customized |
Warranty |
1 year |
Input voltage |
400v/6kv/11kv/35kv |
Output voltage |
200v/220/240/380v/400v/415v/440v |
Operating Conditions
Altitude:≤1,000 meters
Ambient Temperature:
Maximum ambient temperature: +40°C
Maximum daily average temperature: +30°C
Maximum annual average temperature: +20°C
Minimum outdoor temperature: -25°C
The characteristics of the marine environment such as salt spray, humidity, vibration, and limited space require earthing/grounding transformers to meet special design requirements: ① Insulation protection: Use salt spray and mold resistant insulation materials (such as salt spray resistant cast resin), and coat the winding surface with anti-corrosion coating; ② Structural design: Adopt a compact modular structure to adapt to the narrow space of ships/platforms; dry-type (oil-free) is preferred to avoid oil leakage polluting the marine environment; ③ Vibration resistance: Enhance the winding fixing and core clamping structure to meet the mechanical requirements of ship sway and vibration (vibration grade ≥ IEC 60076-5 Class 3); ④ Voltage and frequency: Need to adapt to ship-specific voltage (such as 6.6kV) and frequency (such as 60Hz), and the auxiliary winding needs to meet the power demand of the ship's power station (such as 440V/220V); ⑤ Cooling method: Adopt natural air cooling (KNAN) to avoid fan failure affecting operation and adapt to the closed cabin environment.
Six core parameters must be checked one by one during replacement to avoid compatibility issues: ① System line voltage: Must be consistent with the original (for example, 110kV grade must be replaced for the original 110kV); ② Zero-sequence impedance: The deviation from the original value must be ≤ ±10% to ensure that the protection setting value does not need to be adjusted; ③ Short-time capacity and fault withstand time: Must not be lower than the original grade (for example, the original 30 seconds/5MVA, the new product must meet or be better than this index); ④ Winding structure: Must be consistent with the original type (for example, the original zigzag type cannot be replaced with the wye-delta type) to avoid changes in grounding performance; ⑤ Insulation and cooling method: Must adapt to the original installation scenario (for example, the original outdoor oil-immersed type cannot be replaced with the indoor dry-type); ⑥ Auxiliary winding specifications (if any): The voltage level and capacity must match the original (for example, the original 400V/200kVA, the new product must be consistent) to ensure the normal power supply of the auxiliary load of the substation.
-
15kV 20kV 22kV 30kV 33kV 35kV oil-immersed neutral grounding resistance to transformer (earthing transfoemer)
-
22kV 30kV 33kV 66kV Three phase Oil Immersed Grounding /Earthing Transformer Manufacturer
-
34.5kV 35KV 88kV 110kV Three Phase Zig-Zag Type Oil-Immersed Earthing Transformer source manufacturer
-
20kV 44kV 145kV 150kV Three Phase Oil-Immersed Neutral Earthing Transformer Custom Factory
-
Customization 15kV 30kV 33kV 34.5kV 36kV Three Phase Neutral Grounding/earthing Transformer direct supply
-
Customization Three - phase 11kV 20kV 22kV 30kV grounding/earthing transformers Original Manufacturer
-
Customization 66kV 88kV 110kV 132kV Three Phase Z-type winding Oil-Immersed Earthing Transformer source manufacturer
-
Single Phase Compact Oil Immersed Power Distribution Transformer
-
1250kVA/20kV Electric Single Phase Oil Immersed Power Distribution Transformer
-
Oil-immersed amorphous alloy distribution transformer
-
Design Solution of 24kV Dry Air Insulated Ring Main UnitThe combination of Solid Insulation Assist + Dry Air Insulation represents the development direction for 24kV RMUs. By balancing insulation requirements with compactness and employing solid auxiliary insulation, insulation tests can be passed without significantly increasing phase-to-phase and phase-to-ground dimensions. Encapsulating the pole column solidifies the insulation for the vacuum interrupter and its connecting conductors.Maintaining the 24kV outgoing busbar phase spacing at 110mm,Rockwill16/08-2025 -
Optimization Design Scheme for the 12kV Air-Insulated Ring Main Unit Isolating Gap to Reduce Breakdown Discharge ProbabilityWith the rapid development of the power industry, the ecological concept of low-carbon, energy-saving, and environmental protection has been deeply integrated into the design and manufacturing of power supply and distribution electrical products. The Ring Main Unit (RMU) is a key electrical device in distribution networks. Safety, environmental protection, operational reliability, energy efficiency, and economy are inevitable trends in its development. Traditional RMUs are primarily representedRockwill16/08-2025 -
Analysis of Common Problems in 10kV Gas-Insulated Ring Main Units (RMUs)Introduction:10kV gas-insulated RMUs are widely used due to their numerous advantages, such as being fully enclosed, possessing high insulation performance, requiring no maintenance, having a compact size, and offering flexible and convenient installation. At this stage, they have gradually become a critical node in urban distribution network ring-main power supply and play a significant role in the power distribution system. Problems within gas-insulated RMUs can severely impact the entire diRockwill16/08-2025 -
SF6-Free Solution for Air-Insulated/Eco-friendly Gas Ring Main UnitsⅠ. Technical Bottlenecks of SF₆ SubstitutionInsulation Medium Performance Gapo Dried Air/N₂ insulation strength is only 1/3 of SF₆, requiring expansion of contact gap from 60mm to ≥150mm.o Conventional spring mechanisms lack energy to drive rapid closure of large gaps, easily causing contact ablation due to pre-strike.o Synthetic gases (e.g., C4+CO₂) decompose under arcing, leading to irreversible insulation degradation.Mechanical Structural Limitationso National Grid standardization fixRockwill16/08-2025 -
Implementation Scheme for Installing Lightning Arresters or Voltage Transformers in Gas-Insulated Ring Main UnitsAccording to insulation type, ring main units (RMUs) can be categorized as gas-insulated or air-insulated. The former installs primary circuit components in a sealed metal enclosure filled with low-pressure gas (primarily SF₆ or mixed gases) as the insulating medium, using cable terminals for incoming and outgoing lines. Due to superior insulation, compact size, and modular design, they are widely used in 10kV outdoor distribution substations and prefabricated transformer stations. However, theiRockwill16/08-2025 -
Pressure Relief Safety Solution for Gas-Insulated Ring Main UnitsⅠ. Problem ContextAs a core component in urban power distribution networks, ring main units (RMUs) are widely used in residential areas, factories, and public buildings due to their compact structure, low cost, and high reliability. However, internal equipment failures or arc faults may generate high-temperature, high-pressure gas, leading to cabinet explosions that endanger personnel and equipment. While traditional sealed designs maintain insulation integrity, they fail to rapidly release sudRockwill16/08-2025
