I want to design a suitable RC snubber across the motor to protect two HFKA/012-2ZST relays, which are used to control its two terminals. I don’t know how the formulas in equation (4) are proven—does anybody know? Also, what current should I use in the equation C=I210C = \frac{I^2}{10}C=10I2? I have the motor physically, but I don’t have any part numbers or specifications.

 

If you look at the circuits in that attachment, the snubber goes across the contacts, NOT across the motor!! Is it an AC motor or a DC motor??

 

The current in the equation is the load current. i.e. the motor running current.