How to test if the VFD works well by multimeter

How to check if the inverter is OK with multimeter ?
To check input is OK or not .
Black pen on+. Red pen on R, S, T
Red pen on -, Black pen on R, S, T
Compare the values and see if they are nearly the same. If not, there's problem with the rectifier.

To check output is OK or not .
Black pen on+. Red pen on U,V, W
Red pen on -, Black pen on U,V, W
Compare the values and see if they are nearly the same. If not, there's problem with the igbt or driver board.

[Rajat-hs]

bhai ye + or - terminal ka naam kya hai