Sequential soft start PSU ideas

[chris ma]

Power interuption happens a lot in my area. I am planning to build 8 to 10 channels using 4 or 5 Tor.transformers of 22-0-22 400VA each, and I would like to install 4 or 5 power switchs to power them up as I want. I know how to build a soft start from Rod. E' site. But when the mains power interupts at the time that all channels are on the inrush current for all 4 or 5 transformers is a bad thing I think.

Do you think I need a soft start circuit for each transformer? But I still prefer them to power up sequentially when the mains power come back on after the interuption. Any ideas are welcome.

The Butcher

[Peter Daniel]

You can easily put two of those transformers on a same line without any problems.

How about building instead, a dedicated power lines, just for your stereo, separate for left and right channels on opposite phases?

Appart from not loading your lines at powering on, you will get benefits of dedicated AC power, much better than any soft circuit will provide. And the costs would be negligable, if you do the work yourself.

[jwb]

Why not use 12V remote turn-on system, with each amp activating the next one?

Edit: another idea just occurred to me. In my server room we have a power distribution unit that always applies power in sequence to each outlet after a power failure. It prevents massive inrush condition when the power is restored. You can just buy these on the open market and it sounds like it would be perfect.

[AndrewT]

Hi,
carefull with different phases for the left & right stereo channels.
This means you have 410Vac in the same room and maybe closer than the regs allow.
Lighting & power sockets on two phases in the same room is more acceptable.
regards Andrew T.

[audio-kraut]

This means you have 410Vac in the same room and maybe closer than the regs allow

Not in canada, dear sir - here we run 115/120 or so volts, so split receptacles have a max. of 240V.
By the way, peter daniel - if you do not install the outlets correctly phased - the inspector will be on your case.

Or - did you mean by "phase" the single phase 220V supply coming into your house? - which is split at the house transformer into two 120V legs? they are of the same phase as I was told.

[audio-kraut]

There was a misunderstanding on my part - polarity/vs. phase - although those expressions are used interchangeably..

a dedicated power lines, just for your stereo, separate for left and right channels

If you run separate amps for each channel. But even under conditions where you run more than one amp - active loudspeakers for example, separate lines can only be recommended. I would not like to drive my bryston 4B's on the same leg, so I have installed two dedicated lines from each leg (bus) of the panel box.

There is one problem though - when for reasons unknown the common neutral in the panelbox gets loose in its connector - big mess. This way I had suddenly 220V on each 110V leg - and blew up an adcom line conditioner.

[AndrewT]

Hi,
now I think it's me that has misunderstood.
By phase I mean 3 phase 230/410Vac.
Opposite polarity would be like a bridged amp, with two ac voltages varying either side of neutral.
It is 3 phase that needs safety consideration when the unaware can end up with unintentional 410Vac between live conductors.
regards Andrew T.

[audio-kraut]

Maybe a little better explanation: All receptacles here in canada are "polarized" in the sense that each of the three wires: hot, neutral and ground have marked connectors on the receptacle. The inspector coming to your new installation then checks the receptacles with a "phase tester" to check for the proper connection (no voltage between neutral and ground) The pinsof the plug (cord end) are in a pattern that a plug can be plugged in only one way, so polarity is maintained under all normal circumstances.

The incoming power from the ss (somewhere around 25 kV) gets transformed at the house transformer to so called 220V single phase, balanced power. That means we have two 110 - 120 V legs coming into the house from each tranformer. You are then permitted to run a four conductor wire into a receptacle box - typically all dual receptacles in canada and us - with two hot, one ground one neutral. At the receptacle you then cut the built in jumper between the hot of the dual receptacle. This gives you a full 1500 W available at each part of the dual receptacle instead of the usual combined load of 1500 W for a dual not "split" receptacle. The neutral is still common to both parts of the split dual receptacle.

Some appliances here run also on 220V, so you supply balanced power to a special receptacle - but no neutral in this case.

I hope that lets yuo understand a little better our peculiarities in NA.

[AndrewT]

Hi audio-kraut,
thanks for that. I now understand the references to two supply voltages I have seen in the past in US literature.
regards Andrew T.

[chris ma]

Originally posted by jwb
Why not use 12V remote turn-on system, with each amp activating the next one?

Edit: another idea just occurred to me. In my server room we have a power distribution unit that always applies power in sequence to each outlet after a power failure. It prevents massive inrush condition when the power is restored. You can just buy these on the open market and it sounds like it would be perfect.

Hi,

Can you give more detail about the power distribution unit in your server room, like make and model please?

Hi AndrewT,

Any info regarding those latching switches that have been mentioned lately in the forum. Are they automobile parts?

The Butcher