Help me understand this snubber suggestion

Thread Starter


Joined Mar 17, 2020
Hello All.

I'm using a 3 phase motor amplifier module and the manufacturer suggested I put an rc snubber on each phase, to ground. A 'y' configuration.

I suppose this is supposed to help with ringing in the fets?
How would this look on the schematic. Is it a resistor and capacitor in parallel from each phase to ground?MODULE.jpg
Thank you for looking!


Joined Aug 21, 2008
And yes, the snubber is to take energy from the circuit's inductance and dissipate it in the resistor. It also suppresses ringing in the circuit. That can improve efficiency and keep your circuit from becoming a "radio transmitter" of sorts.

sparky 1

Joined Nov 3, 2018
the capacitor and resistor and there is another component that is across the them called MOV (metal oxide varistor)
it can dissipate heat from over voltage


Joined Jul 18, 2013
For the 3ph motor snubber there are also industrial versions made all in one block by most of the filter suppliers.
If this is a 3ph VFD as @LowQCab surmises, then you should be using a 3ph choke or filter, not a RC snubber, if this is on the motor side of the VFD.
Using the R/C on the output of a VFD can often lead to spurious shut downs.