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Instructions for use of varistor
In order to avoid fire or damage deterioration to the equipment caused by the MOV,please refer to and abide by the following principles:
1) When the varistor is inflowed of high current or high voltage,the MOV itself may be damaged, heating-up , smoke, fire and explosion.       
Varistor or fuse breaker can be assembled at the MOV ends or at both ends of the power supply to avoid this situation.
The following Varistors specification used for reference only:
Diameter:               05D      07D       10D      14D         20D        
Rated current:       1-2A     2-3A      3-5A     3-10A     5-15A
2) Do not allow the inflow current and energy exceeds rated value of varistors. 
3) 200V voltage may be produced between the live line and ground line if grounding fault occurs in 100V three-phase circuit.
4) The varistor is suggested be installed in the 220V power line if it is used in high voltage lines similar to withstand lightning.
5) Other accidents maybe occured due to the effects of fever caused by capacitive impedance of varistor in high frequency applications.
6) Be direct sun exposure or to the ambient temperature of a heater adjacent may exceed the varistor can bear the operation temperature.
7) Varistor need be storaged in a clean, dry environment, avoid being contacted with corrosive or salts.
8) Storage temperature: -10 ~ 40 ℃, ≤ 75% R.H.; avoid varistor temperature changing dramatically.
9) Scaling powder can be removed by alcohol if it exists on surface of varistor.Avoid contact with acetone, thinner or other strong through the larger solvent.
10) Please choose the appropriate resin coating. Some resin coating may influence the properties of varistor.
11) Prohibit the beat or weight pressure.
12) Do not put varistor nearby flammable substances.
13) Please make the pin ends of varistor fixed before cleaning them.
14) When welding, please pay attention to welding points and resin coating of varistors not be melted.
15) Determine the heat dissipation capability of the varistor:
As in the instant of time has great heat effect on the varistor, a heat pulse may therefore not be emited in time and lead to varistor damage.
Varistor can only emit small amount of heat energy, so not suitable for frequent sudden heat generating device.
The higher heat of the working environment,the less proportion of its heat emitting.
Small tip of MOV
Metal oxide varistor is a part for suppressing surge voltage change.
There are polycrystalline ceramic semiconductor particles in the internal structure of MOV,similar as series parallel many "small lightning suppressor."
The resistor value of varistor with very high resistance will fall rapidlly to close to zero when the circuit is opened instantly.