Patented product for two weeks to eliminate spread 30ms grounded arc voltage, the highest domestic standards, microcomputer control devices is currently the only one relay test center by the four state-level anti-jamming test and type test, the use of special depth of unsaturated PT, able to withstand 4 times the working voltage is not saturated, thus virtually eliminating the hidden system resonance over-voltage! Welcome to the owners and friends to switch manufacturers, after the company investigated the specific order! Thank you.