The capacitance to ground is the key difficulty to measure in resonance grounding system. In this paper
a method of signal injection is proposed to measure capacitance to ground accurately. Neutral-point PT is set up as signal injection PT in arc suppression coil
a 25 Hz current is injected form the secondary of the PT. The voltage of this frequency is measured in the terminals of another PT. Using improved TSC arc-suppression coil
which control system is designed based on microprocessor 80C196KC
the automatic tracing and compensation device is developed. It is proved by the test that this device has many advantages such as simple structure; quick-adjusting; high accuracy compensation; less harmonic and high reliability without mechanical mistake.