Instrument supporting zero-sequence current transformer transformer manufacturer of professional power meter Overview: zero-sequence current transformer is fully enclosed cast resin structure, small size, climate adaptability, using external capacitor compensation, protection of high sensitivity; there Φ65mm of for a three-phase cable through the window. Zero sequence current transformer is suitable for indoor, rated frequency 50Hz or 60Hz, rated voltage of 35kV and below the small ground current system for cable grounding protection role of the principle of zero sequence current protection is generally suitable for use in TN grounding system. Because the event of a phase to ground when, on the TN-S system Id loop impedance includes a phase line impedance Z1, PE line impedance ZPE and contact impedance Zf, namely Zs = Z1 + ZPE + Zf; for TN-C system, Id loop impedance including the phase line impedance Z1, PEN line impedance ZPEN and contact resistance Zf, namely ZS = Z1 + ZPEN + Zf; for TN-CS system, Id loop impedance includes a phase line impedance Z1, PEN line impedance ZPEN, PE line impedance ZPE and contact resistance Zf, namely ZS = Z1 + ZPEN + ZPE + Zf, single-phase ground fault current Id generated = 220 / ZS, significantly greater than the three-phase current imbalance without fault, as long as the proper setting, you can detect a ground fault occurs zero sequence current, in order to cut off the fault circuit. And for IT systems, generally require the use of high reliability of power supply, single-phase ground immediately cut off the power supply circuit unnecessary, but need to send out a signal to monitor the breakdown, in order to maintain a period of time to continue to supply the mining industry in the unworthiness of the of phase three-wire cable distribution lines when the single-phase ground, the fault line of zero-sequence current flowing through a system-wide non-fault system capacitive currents, which can easily detect the ground fault current, it can be used zero-sequence current protection device to monitor the relative first ground fault.