AC Line Filter-Parts Recommendations

[croy00]

I'm building an ac line filter. I'm looking for recommendations on:

1. make/model/spec of a common mode nanocrystalline choke (like the one PS Audio uses in its Duet/Quintet). Really searching on this one in terms of size, and how many winds, etc.;

2. What make/model/spec do you consider the "best" sounding X and Y value capacitors for voltage regulation;

That's about it. You can email me direct if you do not wish to post info here: croy0000@gmail.com

I would really appreciate any input.

 

[nigelwright7557]

Heres one I designed into pro equipment for EMC regs.
Worked very well even upto 30 amps.

An externally hosted image should be here but it was not working when we last tested it.

 

[kheng69]

To make a AC line Filter, can a pcb take high current 240 voltage for distribution?

 

[Mooly]

Heres one I designed into pro equipment for EMC regs.
Worked very well even upto 30 amps.

An externally hosted image should be here but it was not working when we last tested it.

Nigel... this might be a typo but if not you might want to recheck those 2u2 (2.2uf) values.

2.2uf as common mode caps (line and neutral to earth) are lethal in fault conditions such as an open circuit ground. Somewhere around 2200 or 4700pf would be more usual and even less than this for medical equipment.

They would also trip many an rcb

As line filters (line to neutral) they are still massive in value and pose a shock risk if the 1M bleed resistor went OC. Typically 0.1uf would be used for these.

 

[Mooly]

To make a AC line Filter, can a pcb take high current 240 voltage for distribution?

Yes of course as long as it's designed correctly with regard to track width and spacing. For high current tracks it's common to see all part of the track heavily tinned.

 

[DF96]

Maybe that filter would satisfy the EMC regs, but get into trouble with safety and the Low Voltage Directive? Was it really intended to be a filter, or power factor correction too?

 

[Speedskater]

While we are on the subject. Jim Brown of Audio Systems Group and the Chair of the AES committee on EMI/RFI has several papers on power line filters.

Audio Systems Group, Inc. Publications

 

[marce]

Tinning wont add alot to the track current capacity, and is not common with todays ROHS finishes such as ENIG, though it will provide a bit of protection if you dont have a solder resist (not from the voltages, the copper from oxidising, but again it aint much of a problem).
I would use a 70micron 2oz copper PCB minimum, the following is what the tracks will carry in terms of current, all figures based on a 10deg temp rise above ambient and an ambient temp of 20 deg C.
2mm = 4A
5mm = 7A
10mm = 10.5A
12mm = 12A
15mm = 14A
20mm = 17.4A
These are conservative figures, they can be calculated for 20 deg above ambient, but I prefer to have as big a margin for safety as possible, especialy as mains and high current is one of the main causes of house fires.

 

[marce]

Some EMC/RF related info
A Practical Interference Free Audio System (Part 2)

Designing for Interference-free Audio System Components

 

[Speedskater]

Any papers by Tony Waldron and/or Keith Armstrong are well worth reading.

 

[marce]

My hero's, well two of them, also been lucky in the past to work at firms that have had EMC training conducted by Mr Armstrong...
A lot of thier articles apear here, there is also a USA version of the site:
EMC Information Centre - The EMC Journal (Free in the UK)
Cheers for the other link Speedskater, I've posted it home so I can have a browse as I am always interested in any info on EMC and EMI etc

 

[beetel]

http://classicvalve.ca/docs/CK-39_Power_Line_Filter_PCB.pdf