Surge Protection Performance of Metal Oxide Varistor in Low Voltage Circuits

초록

Damage and upset of control and communication equipment due to transient over-voltages which caused primarily to internal switching surge and external lightning surge are important problems in electromagnetic compatibility(EMC). This paper analyses operation characteristics of metal oxide varistor widely used in low voltage ac line with EMTP, and compares them with experimental results. In addition, we model combination generator producing 1.2/50㎲ open circuit voltage and 8/20㎲ short circuit current as a source which is critical in calculating operation characteristic. Results of the simulation showed that most of transient energy are consumed at MOV located in service entrance side than load side, and they were similar to experimental results. Therefore, it was proved that MOV at the entrance side has more energy capacity than that of MOV at the load side.