mains filter

[pooge]

I use Corcom filters -- easier than assembling the parts -- they work quite well (very well indeed). In fact, the price of a corcom filter is about what you would expect to pay if you had to assemble the parts from scratch.
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Any info on picking an appropriate Corcom for the job, i.e., for DAC vs. low level analog appliance?

 

[abraxalito]

now he has two "live" lines, where there has only been one before, and a floating earth tied to a home power socket. That doesn't fills me with confidence.

Can't see the 'floating' bit on his schematic - that's definitely an earth symbol he's drawn. Each wire is only half as live as the previous single live wire. Works for me, I get a reduction in 50Hz leakage around 20dB by using such an arrangement.

 

[Speedskater]

Probably the big difference is the the GFCI's are more sensitive. They trip at 5 ma. leakage rather than 30 ma. So some power conditioners on some noisy power lines that dump the noise current to the safety ground (PE, EGC) will trip the GFCI.

But my question really was, how would you mount a RCBO and RCCB breaker inside a piece of equipment? Mounting a GFCI breaker would be ugly,

 

[macboy]

Pick a filter with appropriate current/wattage rating for the component/device for which it is filtering the power. Don't put a 10 A filter on a component that draws 100 W. You will get generally get better filtering from a 2 A rated filter than the 10 A one. This is mainly because the inductors can be of higher inductance on the lower current filter; on higher current filters, the inductance needs to be reduced to prevent saturation. OTOH, a physically very large 10 A filter may have much better filtering than a physically small (IEC socket sized) 2 A one. For a given size (and price range), the lower the current rating, the better the attenuation of noise. A quick scan of a manufacturer's product line data sheets or brochure will confirm this.

 

[Juergen Knoop]

Can't see the 'floating' bit on his schematic - that's definitely an earth symbol he's drawn.

ah, I see...but where is that earth connected to? The incoming PE seemed connected to the transformers static shield only.

 

[abraxalito]

A quick scan of a manufacturer's product line data sheets or brochure will confirm this.

I wholeheartedly second your comments about picking the current rating of filter which applies to the particular unit. Worth bearing in mind that manufacturers want their filters to be shown in the best light (who wouldn't? ). That means they'll show HF attenuaton with a ground-plane earth - read clean, low inductance. In reality the HF rejection of filters is fairly sensitive to inductance in the ground lead and, naturally enough to noise carried on it. This is most especially true of filters relying on Y-caps for their effectiveness.

 

[jrockhead]

Any info on picking an appropriate Corcom for the job, i.e., for DAC vs. low level analog appliance?

Check out the 6EHQ1 Corcoms. They have attenuation specs down to 10 Khz.
I use them in almost everything in my setup.

 

[abraxalito]

http://www.corcom.com/PDF/HQ.pdf

More impressive is the 30dB typical common-mode performance at 30MHz. Looks like an excellent choice for digital kit though it would be nice to see how they get on above 30MHz.

 

[mavallarino]

RCBO and RCCB are mains electricity safety devices.
Residual Current Breaker means much the same as Earth Leakage Breaker.

If mains current is leaking to earth the device notices that the Live current is not the same as the Neutral current and opens the contacts to isolate the apparent fault (current leaking to earth).

These devices were not intended to be fitted to the secondary side of an isolating transformer.

Remember they measure the difference between the Live current and the Neutral current and when that difference exceeds a preset threshold the breaker opens.

Thanks AndrewT. What you're suggesting, then, is to place the RCBO before?
The secondary will be balanced (115 - 0 - 115) and I was wondering how the device would correctly on this.

 

[mavallarino]

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

Thanks, I was thinking a balanced setup.

 

[mavallarino]

now he has two "live" lines, where there has only been one before, and a floating earth tied to a home power socket. That doesn't fills me with confidence.

It's not exactly clear what your concern is. I need to ground the primary side to the secondary side? I wouldn't think so. If not, what are you suggesting?

 

[mavallarino]

Probably the big difference is the the GFCI's are more sensitive. They trip at 5 ma. leakage rather than 30 ma. So some power conditioners on some noisy power lines that dump the noise current to the safety ground (PE, EGC) will trip the GFCI.

But my question really was, how would you mount a RCBO and RCCB breaker inside a piece of equipment? Mounting a GFCI breaker would be ugly,

You're right Speedskater. It's an ugly installation and I already have a solution. (more to come). It isn't impossible and since I already have one I would like to know where the best place to place it (prim. or sec. side).

The difference in sensitivity depends on the rating of the device. Mine is 30mA, model ABB DS202C.
Thanks

 

[mavallarino]

Hello all, two points to highlight:

1. this is a balanced output
2. the tx is shielded and isolated with balanced output (115 - 0 - 115)

Since the tx is already filtering DC is it really necessary so much additional filtering, and if so, for what devices?

My amps on commercial power conditioners/filters sound worse, any ideas why?

 

[Speedskater]

I think that I would use the RCBO as the very first thing on the primary side as a multifunction device.
It's not as ugly as US GFCI breakers.

 

[wwenze]

It's not exactly clear what your concern is. I need to ground the primary side to the secondary side? I wouldn't think so. If not, what are you suggesting?

The major issue is what does the 3-line triangle mean in your drawing.

If it is earth, as in the concrete you are standing on, you will die if you hold the L and stand on the same concrete. And it won't trip the RCD on the primary side.

 

[mavallarino]

The major issue is what does the 3-line triangle mean in your drawing.

If it is earth, as in the concrete you are standing on, you will die if you hold the L and stand on the same concrete. And it won't trip the RCD on the primary side.

Now I understand what you mean. Yes, you are right. The 3-line triangle symbol is in fact destined to the building earth (not ground as in diagram).
The diagram is incorrect and now I will amend it for the next version. In this case the yellow/green wire since this is arriving from a standard plug. If the earth stays constant from building to primary it will trip the RCD, and, on both sides because they are mechanically coupled to each other.

However, I'm not sure how I will connect this on the transformer (in arrival in the next couple of days) since there will also be a shield to contemplate.

Thanks!