EMI mitifation

Hi,

I am running three NEMA23 format steppers ( 3A rated ) and a three phase VFD. I will be using shielded cable for the VFD to spindle but wanted to use flat ribbon cable for the motors.

The reason for that is that flat cable from forklift trucks can act as it's own guide, if it has a flat support ( no guide chan etc. ) and has good gauge copper stranded wire.

I have enough conductors to alternate each motor wire with a grounded wire.

max x rate is about 3600 mm/min = 60 mm/sec ; at 80 half steps / mm it will max under 500 pulse / second with harmonics running much higher than 500Hz.

Will that kind of transmission line format be sufficient to control EMI ?

I am currently running a 32V supply to the motor drivers.

Thanks for any advise.

Your post has lots of disjointed subjects. What has a 3-phase VFD to do with your project? Basically you need to determine If your EMI control is for radiation or susceptibility. In other words, is your problem in RFI generation or reception?

Paul

Good point. My main concern is EM interference with other equipment, eg. neighbour's radio etc.

I should also mention length: the longest run of the ribbon type cable will be under 2 meters long.

ardnut: Good point. My main concern is EM interference with other equipment, eg. neighbour's radio etc.

I should also mention length: the longest run of the ribbon type cable will be under 2 meters long.

If it doesn't bother your radio, it won't bother the neighbor's. Use your radio as a test instrument.

Paul

ardnut: Hi,

I am running three NEMA23 format steppers ( 3A rated ) and a three phase VFD. I will be using shielded cable for the VFD to spindle but wanted to use flat ribbon cable for the motors.

Never seen ribbon cable with thick enough strands for non-toy motors - I'm intrigued by this cable from fork-lifts - is it available somewhere online? Sounds useful if its happy with 3A.

With ribbon without twists you'll always get more EMI than twisted pair radiated, but you can also get copper-braid screening for ribbon cables which might be an idea?

Basically you need to determine If your EMI control is for radiation or susceptibility

Surprisingly these are normally the mirror image of each other according to the compliance department of where I worked. If you get one under the limit then it is more than likely both will be under the limit. Of course they are not identical but they are a lot closer than I expected them to be.