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