How to switch on a POWER SUPPLY w/o sparks

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izeman   100 GW

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How to switch on a POWER SUPPLY w/o sparks

Post by izeman » Oct 22 2020 9:17am

I got some of those AC/DC supplies for charging big batteries. Those Kingpan, whatsoever named types. I guess most of you know them. Come in different wattages and are quite capable.

I now use one to power a programmable desk power supply that takes 60V as input and needs up to 600W, so the PS is ideal for that.

But I don't want it powered on all day long. They have a little switch on the side, but this is bad quality and tends to melt. The PS has big capacitors that cause my USV to start when I plug it into the wall socket. The power surge seems to be quite immense.

So I'm looking for a proper way to turn those on and off.

Any ideas?

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fechter   100 GW

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Re: How to switch on a POWER SUPPLY w/o sparks

Post by fechter » Oct 22 2020 11:49am

Normally I see a NTC inrush limiter in series with the bridge rectifier or AC line to soften the turn-on.

Here is an application note:
https://product.tdk.com/info/en/product ... miter.html
"One test is worth a thousand opinions"

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izeman   100 GW

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Re: How to switch on a POWER SUPPLY w/o sparks

Post by izeman » Oct 22 2020 1:02pm

Thanks fechter. How would I size this NTC? We got 220V and the PS has a 800W rating. So the NTC has to withstand 5A?

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izeman   100 GW

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Re: How to switch on a POWER SUPPLY w/o sparks

Post by izeman » Oct 23 2020 1:26am

This one is ONE Ohm and 20A. Would that suit? It's quite pricey though as well ;)

https://www.conrad.at/de/p/tdk-b57464s0 ... 19752.html

or 10pcs of it from aliexpress for the same price ;)

https://www.aliexpress.com/item/1047795 ... hweb201603_

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fechter   100 GW

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Re: How to switch on a POWER SUPPLY w/o sparks

Post by fechter » Oct 24 2020 12:55pm

There are some formulas you can use to see what size is recommended. I think the one you linked to will work but may be overkill size wise, which would be OK. The thing I linked to had a PDF link but you need to request it with a form.

Here is another selection guide:
https://www.powerelectronics.com/commun ... plications
"One test is worth a thousand opinions"

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