Need Help with EMI/RFI Line Filter - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 26th August 2006, 05:14 PM   #1
auric is offline auric  Canada
diyAudio Member
 
Join Date: Aug 2006
Default Need Help with EMI/RFI Line Filter

Hi:

I 'm wondering if someone could give me some pointers on how to wire a high current EMI/RFI Line Filter.

A while back I found a large (8"X15"X2") West-Cap AC EMI/RFI Line Filter. It is specified as 250 VAC 2X30AMP.

The filter is a large square tin box with 2 screw terminals on the input side and 2 screw terminals on the output side. There is no terminal for ground; I assume that it is just the metal case.

Some questions:

1) This appears to me as a "single phase" line filter. Live + Neutral for the input terminals and the case is ground.

Why is it specified as 2X30 AMP?

Many filters that I have seen including the ones built into the IEC modules are just specified as 10 AMPs.

2) How do I wire this filter?

Smaller EMI/RFI filters are wired "Live" to one terminal and "Hot" to the other terminal with "Ground" to the case.

When I wire this filter in this configuration, I get a sizable current draw even when there is no load on the filter.

Any ideas?

Many Thanks!

Derek
  Reply With Quote
Old 27th August 2006, 03:22 PM   #2
BWRX is offline BWRX  United States
diyAudio Moderator Emeritus
 
Join Date: Jan 2005
Location: Pennsylvania
2 input terminals and 2 output terminals sure sounds like line and neutral in and line and neutral out.

How much current is "sizeable"? Can you open it up and snap a photo or draw up a quick schematic?

The common mode choke in most filters is two windings (line side and neutral side) on the same core. 2x30A most likely means that both sides of the filter are rated for 30A.
__________________
Brian
  Reply With Quote
Old 27th August 2006, 04:20 PM   #3
auric is offline auric  Canada
diyAudio Member
 
Join Date: Aug 2006
Hi Brian:

Thanks for your reply.

When testing "unknown" devices I wire a 100watt light bulb in series with the load to provide current limiting.

With the neutral connected to one terminal and live to the other the bulb glows about 35-50% brightness. There is no load on the filter.

Derek
Attached Images
File Type: jpg p1070670.jpg (53.3 KB, 190 views)
  Reply With Quote
Old 27th August 2006, 04:55 PM   #4
BWRX is offline BWRX  United States
diyAudio Moderator Emeritus
 
Join Date: Jan 2005
Location: Pennsylvania
I'm a little confused because you said you wired the light bulb in series with the load but you also said there was no load on the filter.

Did you mean you put the light bulb in series with the line input to the module and left the output terminals open and the light bulb was lighting up?
__________________
Brian
  Reply With Quote
Old 27th August 2006, 05:07 PM   #5
auric is offline auric  Canada
diyAudio Member
 
Join Date: Aug 2006
Hi Brian:

When I wrote wiring a load in series with the light bulb, I was referring to the Line Filter as the "load."

To clarify, the "input" of the line filter is wired in series with the 100 Watt light bulb.

There is no load attached to the output of the line filter.

When I power the line filter up with the light bulb in series, the 100 Watt light bulb glows to about 30-50% brightness which is a good current draw with nothing attached to the output of the line filter.

Thanks,

Derek
  Reply With Quote
Old 27th August 2006, 05:11 PM   #6
BWRX is offline BWRX  United States
diyAudio Moderator Emeritus
 
Join Date: Jan 2005
Location: Pennsylvania
The only way to find out for sure is to open up that sucker and see what's inside

Most filters have a large value resistor between the line and neutral but that sure shouldn't cause a light bulb to illuminate as much as you saw. Maybe some cap inside has shorted out? How old is that monster?
__________________
Brian
  Reply With Quote
Old 27th August 2006, 08:16 PM   #7
auric is offline auric  Canada
diyAudio Member
 
Join Date: Aug 2006
Hi Brian:

From the schematics online of similar filters, I have noted a 470K bleeder resistor between the live and neutral to discharge the capacitors.

I don't know how old it is, but probably a few years. I picked it up in "new" condition at a surplus store. It was in a card board box without notation.

When I put an ohm meter across the input I can see the caps charging up.

I'm still a little bit thrown off by the 2X30 amp designation. I understand your explanation, but not sure why nobody else such as Corcom etc... expresses it this way.

Can this thing be used "single ended?" Perhaps just leave one set of input/output terminals disconnected. And then feed the live in series with the with filter on the other set of terminals?

Derek
  Reply With Quote
Old 27th August 2006, 08:27 PM   #8
BWRX is offline BWRX  United States
diyAudio Moderator Emeritus
 
Join Date: Jan 2005
Location: Pennsylvania
It looks like it could be more than a few years old. Even so, you're going to have to open it up to figure out why it's doing that.

I searched a little using the numbers on the case in the picture and found nothing of value.
__________________
Brian
  Reply With Quote
Old 27th August 2006, 09:04 PM   #9
auric is offline auric  Canada
diyAudio Member
 
Join Date: Aug 2006
Hi Brian:

My friend thinks this it is designed for 240 V or 208 V feeds like the ones coming into our houses and which power the stoves and dryers. I.e. Two out of phase hots at 240/208V, but 120/104V from eithr hots to neutral.

There is no neutral connection on the filter. The terminals are both for the hots and the case is grounded.

If the two inputs to the filters are driven out of phase, the current draw may drop.

The question then is, can it be used in single ended mode for 120 V operation?

What do you think?

If I open it up, I'll learn something but then I won't be able to use it anymore

Derek
  Reply With Quote
Old 29th August 2006, 04:22 PM   #10
BWRX is offline BWRX  United States
diyAudio Moderator Emeritus
 
Join Date: Jan 2005
Location: Pennsylvania
I think your friend is right.

As for using it single ended - I wouldn't just because it was not intended to be used like that. Like I said before, I wouldn't feel comfortable using it how you want to without knowing what's inside first. There's no easy way to open it up without destroying the enclosure?

You could always use it between a 240V outlet and a 240V appliance and see if it cuts down on junk spit out on to the other AC lines in your house.
__________________
Brian
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Which line filter is best? Stu_M Parts 51 15th June 2009 12:34 PM
hi-end Line filter umut1001 Power Supplies 10 27th June 2008 12:30 PM
60hz Line filter for PSU triden Power Supplies 3 25th November 2007 08:58 AM
line filter design. AudioGeek Power Supplies 3 9th April 2007 07:20 PM
Line Filter for Gainclone Bassterror Chip Amps 2 1st October 2006 11:23 AM


New To Site? Need Help?

All times are GMT. The time now is 01:01 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2