A tap-changing arc-suppression coil is equipped with multiple taps. A load-tap changer is used to adjust these taps, thereby altering the inductance value and controlling the ground inductive current output, thus achieving automatic tracking compensation.  

Working principle:

When the power grid is operating normally, the microcomputer controller of the arc-suppression coil calculates the ground capacitance current under the current grid configuration by performing real-time measurements and computations. Based on a pre-set small residual current value or detuning degree, the controller determines the tap position at which the arc-suppression coil should be set. The controller then controls the on-load tap changer to adjust the coil to the required compensation tap position. After a ground fault occurs, the residual current at the fault point can be limited within the preset range, thereby effectively extinguishing the arc.

  Performance features:  

The compensation adjustment method of the tap-changing arc-suppression coil complete set of equipment is a pre-adjustment approach. That is, before a single-phase-to-ground fault occurs, the arc-suppression coil has already been adjusted to an optimal compensation state based on the system’s capacitive current in the power grid. The response time for ground fault compensation is determined by the thyristor short-circuit damping resistor time, ensuring a fast response.

The core and coil structure is stable and reliable in operation, free from nonlinear harmonic interference and noise. It can be manufactured with very large capacities, features a simple design, boasts extensive operational experience, and enjoys widespread use.

The device can be optionally equipped with a low-current ground-fault line selection function. Leveraging the structural characteristics of tap-changing arc-suppression coils, it can employ the active power method, the standard comprehensive line-selection method, and the parallel-resistor line-selection method for ground-fault line selection. Among these methods, the parallel-resistor line-selection method is currently the most accurate, thereby significantly improving the accuracy of ground-fault line selection.  

Technical specifications:  

Applicable voltage levels: 6kV, 10kV, 35kV, 66kV

Rated frequency: 50 Hz

Compensation and adjustment method: Pre-adjustment

Capacitance current measurement error ≤ 2%

Number of adjustment levels ≤ 25 levels

During a single-phase ground fault, the residual current ≤ 5A.

During system operation, the displacement voltage ≤ 15%.

Grounding response time: ≤60 ms

Control method for grounding systems: real-time online monitoring and automatic compensation.  

Structural components of a tap-changing arc-suppression coil:

A complete set of tap-changing arc-suppression coils typically consists of a grounding transformer, the main body of the tap-changing arc-suppression coil, a on-load tap-changer switch, a microcomputer controller, a control panel, a damping resistor box, current transformers, voltage transformers, surge arresters, and isolating switches. The overall structural diagram is shown below: