Metal oxide varistor (MOV) is a semiconductor element with a unique grain boundary structure. Its resistance value decreases sharply with the increase of voltage. It has excellent nonlinear volt-ampere characteristics, as well as high current capacity, the lower residual voltage, no freewheeling and lower cost. That’s why mov has been the first choice to be used in power and signal ports as over-voltage protection components.

Although the current capacity of the MOV itself is large, the energy capacity is not large, that is, its rated continuous power is very small. The commonly used MOV rated power is generally mW level, which cannot withstand the constant current. For example, when a MOV runs in a U=53V circuit, a leakage current of 100μA is generated due to aging. According to P=UI, substituting U=53V and I=100μA, the calculated heating power consumption is 5.3mW, which is the same level as the power of the MOV itself. When the MOV leakage current reaches the milliampere level, it is enough to exceed the continuous power that it can withstand, causing combustion problems.

In view of the burning problem caused by the failure of MOV, the current mainstream industry adopts the blocking method, which has many shortcomings and cannot achieve the purpose of truly solving the burning problem of MOV. The latest research technology adopts sparse methods to prevent warnings and deal with them in advance, so as to truly eliminate the burning problem of MOV. At present, Anhui Jinli which is one of the best spd (surge protective device) manufactures in China conducts in-depth experimental research on two aspects of abnormal temperature and abnormal leakage current.