11kV 15kV 20kV 22kV Three-Phase Oil-Immersed Earthing/Grounding Transformer China Manufacturer

Description

Earthing transformers are classified as standard reactors. An earthing transformer (neutral coupler) is a three-phase transformer connected to the power system to provide a neutral connection for earthing, either directly or via impedance. The earthing transformers may, in addition, supply a local auxiliary load.

During single-phase faults, the reactor limits the fault current in the neutral, and the restoration of the power line is improved. According to the IEC 60076-6 standard, the neutral-earthing reactor is connected between the neutral of a power system and the earth to limit the line to earth current under system earth fault conditions to the desired value. 

The earthing transformer creates a neutral point for a network. ZN connection is usually applied. Z connection provides linear and specified zero sequence impedance. YN + d can also be applied. 

Features

Functional Uniqueness:

• Constructing an Artificial Neutral Point: Provides a reliable neutral point connection for systems with ungrounded or high-impedance grounded neutrals (such as IT systems and resonant grounded systems).

• Grounding Path Management: The neutral point can be directly grounded or grounded via a reactor/resistor, precisely limiting single-phase ground fault current (in line with IEC 60076-6).

Fault Current Control:

• Suppressing Fault Current: Limits the ground fault current to a safe valuev by connecting a neutral reactor in series, preventing equipment damage.

• Accelerating System Recovery: Reducing the magnitude of the fault current helps the arc self-extinguish, shortens power outage duration, and improves power supply continuity.

Winding Connection Methods:

• ZN Type (Zigzag Connection): A mainstream design that provides linear zero-sequence impedance, with strong magnetic circuit balance and anti-saturation capability.

• YN+d (Star + Delta): The secondary delta winding can supply auxiliary loads (doubling as a station service transformer function).

• Controllable Zero-Sequence Impedance: Impedance values can be customized to ensure precise matching with the system protection strategy.Safety and Standard Compliance:

• Following IEC 60076-6: Regulates the temperature rise, insulation, and short-circuit withstand capability of neutral reactors.

• Overvoltage Suppression: Limits transient overvoltages caused by ground faults, protecting equipment insulation.

Main Technical Parameters

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.

Main Application Areas

• Industrial Power Distribution: Grounding protection for plant electrical systems in petrochemical, metallurgical, and mining industries

• Grid Infrastructure: Neutral grounding retrofits for urban distribution substations and switching stations

• New Energy Stations: Grounding systems for grid-connected sides of distributed photovoltaic plants and biomass power generation

• Transportation Power: Grounding devices for electrified railway traction substations and metro power supply networks