42Vac Input power supply

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Haha that's the easy part.. :-)

Output 50V 1.2Adc (regulated, can drop 1 or 2V at full load) centre tapped (+ and -25V), current draw can vary from almost 0 to full. Again not too hard.

Input range 35Vac-46Vac, no sweat.

Isolated-Sine wave current draw and unity power factor (or close) :shock: well at least for me. No large input caps for starter as I understand.

This project has been on and off for several years, now it seems back on. I have looked at National switchers and a few will handle the input and output voltage and current requirements but ideally I would need a similar device as those used in universal power supplies with 90-230Vac inputs but for lower voltages in.

Have tried Power Integration but they are really not that interested. May have several hundred unit per year sale.

Did I mention it should not cost much more that the current 240V 50VA transformer?....

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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The input frequency is 50/60Hz? What outputs/generates 42VAC?

What about a standard 1:1 isolation transformer like this one?

I guess the transformer does not really care when it's fed 42 or 230VAC.

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The input frequency is 50/60Hz?
50 Hz
Quote:
What outputs/generates 42VAC?
A dirty big transformer (240V-42V) feeding equipment.
Quote:
What about a standard 1:1 isolation
That's what we have used in the past, the power factor correction and the sine wave current draw requirements are not met, therefore the need for some form of fancy regulated supply.

Maybe we will end up using the transformer for isolation and some other fancy regulated supply to meet the above, I don't have much of a clue what though. Using a SM supply we could get rid of the bulky (and expensive) transformer and use a higher frequency type.

The transformes CARES if you feed 230V or 42V if you want to get least power waste. We have specially designed transformers with 42V primary (thick wires, less turns etc.)

Funnily enough it seems that the Netherlands started the ball rolling with their 42V traffic light systems and other industries have followed. This is in order not to distribute mains around where people could get hurt in case of accidents.

Think of a car accident knocking down a traffic light pole and having live wiring around. it seems that welding equipment, lifts (elevators for some) and others are moving away from having mains spread everywhere. 24Vac, 42Vac, 48Vac and 56Vac are being used.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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An AC fed PS includes a rectifier followed by a bulk capacitor, then a DC/DC converter. The power factor and harmonic distortion will be horrible.

You need some form of power factor correction circuit, can be passive or active.

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You need some form of power factor correction circuit,
Hints? :-) That's the bit I don't quite understand as I have never done it before.

I know I can't have a bulk cap after the bridge and I know of some chips (ST??) that will do PFC but I have put the info in a safe place so I would not lose it...if I can only remember the safe place! :evil: Maybe got wiped out in the last HDD changeover.

Some application notes would come in handy.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Look up the L6562A. IIRC that's a widely used FPC controller.