In the power grid with no neutral grounding, when the grounding capacitive current is too large, it will cause a serious threat to be the safe operation of the system, so the Regulations provide that if the grounding capacitive current is greater than a certain value, arc-suppression coil shall be installed for compensation. To select the appropriate capacity of arc-suppression coils or adjust the installed old arc-suppression coil, the system shall first be measured for its grounding capacitive current.

The measurement methods for grounding capacitive current include direct grounding and indirect measurement. The direct grounding method means that an artificial single-phase grounding fault is produced in the system to directly measure the current through the grounding line. This method features more operation, complex wiring and higher degree of risks, and it may easily lead to breakdown of the poor insulation to result in two-phase short-circuit accident, so it is generally not used. The indirect measurement, namely, the use of external capacitors, can avoid the drawbacks of the direct grounding method, but the measurements are still related to the primary side, so it also features more operation, complex wiring and higher degree of risks. To eliminate the above-mentioned problems, our company’s technical staff has successfully produced a “THT-DRC type capacitive current tester” after years of hard work. If this tester is used, you only need to connect the two terminals of the bus PT open delta to the two signal output terminals of the instrument, and press the “Measure” button, and you can accurately measure the system grounding capacitive current quickly, conveniently and safely.