In article .com,
"Pete C." wrote:

Ignoramus24925 wrote:

Joe, I will get a shielded cable for the motor leads, and will ground
the cable, and will also add those filters. If I recall correctly, the
cables from the motors connected to the main terminal block, are not
that shielded, so if I shield the cables going from drives to terminal
block, it is only half the battle.

i

You can get flexible metal conduit (Greenfield) at Depot or Lowe's and
fish your motor (both spindle and servos) through the conduit to provide
shielding. It's cheap stuff, I just got a 25' roll of 1/2" FMC at Depot
for $10. They also have 3/8" size which may be better for the servo
power leads.

Either will work. As will regular conduit in areas not requiring flexibility.
Nor is there any harm in doing both shielded wire and conduit, although there is
no electrical advantage either. Greenfield and conduit are immune to hot chips
melting a hole, though.

It's important to ground the shield where it passes through a shield wall, like
the motor case and the cabinet where the VFD lives. If the VFD isn't in a metal
cabinet, then ground the VFD end to the frame of the VFD.

For the record, this VFD ground is an extension of the safety (green/bare)
ground system, and not the neutral (white).

I'm suspicious of the VFD terminal block - it may be the power neutral, versus
the safety ground. The VFD frame ground (usually with green screw) is safe and
correct.

They also make line inductors that go between VFD and motor that reduce
interference by reducing the edge speed of the switched waveform that the motor
sees as a varying-frequency sine wave. However, such inductors are very big and
expensive, and very unlikely to be needed for such a small motor. (I have no
such thing on my VFDs.)

Joe Gwinn