Capacitance Current Tester

Currently, the neutral point of our country's power system is generally not directly grounded, so when a line has a single-phase grounding, the current flowing through the fault point is actually capacitive current generated by the line-to-ground capacitance. According to statistics, a large proportion of power system faults are caused by excessive capacitive current during single-phase grounding, leading to arc formation and the inability of the arc to extinguish itself. Therefore, our country's power regulations stipulate that whenWhen the capacitive current in a 10kV and 35kV system exceeds 30A and 10A respectively, an arc suppression coil should be installed to compensate for the capacitive current, which requires measuring the capacitive current to make the decision. Additionally, the ground capacitance of the power system and the parameters of the PT can cause magnetic resonance overvoltage in the PT. To verify whether the distribution system will experience PT resonance and what type of resonance it will be, it is also necessary to accurately measure the ground capacitance value of the power system.

Traditional methods for measuring capacitance current include direct methods with single-phase metal grounding and indirect measurement methods using additional capacitors. These methods require contact with primary equipment, thus posing risks of testing hazards, complex operations, and low work efficiency. Consequently, the need arose for...PT secondary side injection signal method for measuring grid capacitive current; compared to traditional measurement methods, the test instrument does not requireConnected directly to the side, the test is non-hazardous; thus, there's no need for complex safety procedures or to wait for lengthy scheduling commands. Simply connect the measuring line.PT's open triangle terminal can measure the data of capacitance current. The weak heterodyne test signal is injected from the PT's open triangle, ensuring it does not affect the relay protection or the PT itself, while avoiding the 50Hz power frequency interference signal.

However, the existing ones based onThe PT secondary side injection signal tester is bulky and heavy, which hinders portability and is not suitable for large-scale testing conditions. Additionally, such testers have limited measurement accuracy for power grids connected in a 4PT configuration.Extreme.Low, difficult to meet user needs; requires change.Only PT connections can accurately measure the system's capacitance current.

To address these issues, our company has developed the previous generation based on...Based on the PT Secondary Side Injection Signal Tester, we have developed a new generation of product, the Capacitance Current Tester, through a redeveloped and redesigned approach. It incorporates a brand new hardware structure, a faster ARM processor, and an AD converter, and features an all-digital variable frequency inverter power supply, which is efficient, generates less heat, is compact, and lightweight. Compared to the previous generation, the new model significantly reduces both size and weight, making it more portable and convenient for on-site testing. It also introduces a new measurement method to address the issue of low accuracy in grid capacitance current testing for 4PT connection methods. Zero sequence 3U0 voltage can be accurately measured at any time (including during the measurement process), facilitating users in judging the system's operational status; and during testing, if the zero sequence 3U0 voltage is too high, the measurement process can be automatically stopped.

The test instrument features an industrial color LCD screen (readable under bright light), Chinese menu, and a more user-friendly human-machine interaction, and is equipped withUSB drive storage and data printing functions. Easy to connect, with fast testing speed, high stability, and accuracy in data, significantly reducing the labor intensity of testers and improving work efficiency.