A Novel Restoring Over-voltage Protection Equipment for Power Frequency Insulation Experiments

A protection equipment of restoring over-voltage is presented based on theoretical analysis when a flashover of tested equipment occurs in power frequency insulation experiments, to which the testing voltage is applied from a testing transformer. The main circuit of protection equipment is a group of fast power electronics switches reversely paralleled on the side of testing transformer's primary winding. The control part is mainly composed of input circuit, amplifier, electrical level comparator, timer, forming pulse circuit and strong trigger. In the interest of enhancing the anti-interference capability and reliability of restoring over-voltage protection equipment, the techniques of the potential suspension, shield, analogical isolation, photoelectric isolation, signal conversion, optical cable transmission and so on are adopted. When the flashover or breakdown of tested equipment occurs, the fast power electronics switches of protection equipment make the primary winding be a short circuit and secondary winding be power off. This equipment can effectively restrain the repeated flashovers and the restoring over-voltages on tested equipment. The restoring over-voltage protection equipment has been used successfully on some site two years