Notification 642 -–– MOV Clamping Current too low  

CATEGORY

ISSUE / RESULT

FIX / REFERENCE(S)

Information

Clamping current of Varistor is too low. This may cause the voltage on the primary Switch to rise above the breakdown Voltage.  

  • Use MOV with higher clamping current.  

 

The clamping current of a Varistor is the current that will flow through it when the voltage at the terminals of the MOV is at a certain level (for 275V MOVs this voltage is typically 710V). A lower clamping current means that the voltage at the varistor will actually rise more than a MOV with a higher clamping current (for the same surge event).