Snubber CCT on DC Shunt Motor

[ElecEIT]

Hello,

A 440V shunt field DC lathe motor is powered from a three phase rectifier circuit. The motor was previously powered from a m-gen set until it burnt up a few years ago. The motor is equiped with dynamic braking. The rectifier was equipped with 1000V diodes. All six diodes blew whenever the dynamic brake was applied. The diodes were upgraded to 1600V and now an internal regulator blows when the brake is applied. A snubber network is required at the output of the regulator to supress the transient spike. Any suggestions on where to look for R and C calculations.

Thanks

 

[illiterate]

use a varistor rated for the correct voltage

If dynamic braking is being used ensure the supply is
disconnected before the braking resistor is applied. If not the supply will see a spike of current as it tries to supply the Dynamic braking resistor.