Is a neutral required on the line side of a wye 3 ph line filter

[MSASTEEL10]

Hello!! I need some help here...We are using a 3 phase, 5 wire line filter in front of an industrial PC control power supply. We have contactors on the 3 phase load side after the filter that we believe are causing some issues with the control. We do not use the neutral on the Load side, so we do not require the neutral on the Line side. I believe this to be degrading the load voltage because the the capacitors in the filter couple each of the lines to the neutral and ground. Is my rationale valid or does it not matter since we do not have a load connected to the neutral on the load side?

 

[al hildenbrand]

Are you connecting the filter to the Equipment Grounding Conductor?

 

[zbang]

If you think of the filter as a load and it needs a neutral, then whether or not you take a neutral from the filter, you need to bring one to it.

You might also look at the manufacture's instructions- if they say to connect the neutral, you need one.

 

[synchro]

I agree with zbang's comments.
What is the nature of the problem you are seeing? For example, is there a problem when the contactors first close and then it settles down? Or does the problem persist? Also, is the reason you are filtering the line to clean up the line for the supply input, or do you want to reduce any noise that the supply itself may be creating on the line inputs?

 

[jaggedben]

To concur with other posts: how do the capacitors couple line to neutral if there is no neutral brought to the equipment? It seems to me that both of those things cannot be right.