Electrical – Simple soft start for high power mains device

current-limitingpower

I have seen, but cannot find again, a really simple implementation of a mains soft start circuit.
The thing I'm thinking of involves a power resister inline of the mains. When the device is started, current is restricted until a relay is energised, which shorts out the resistor allowing full power

The thing is, I can't remember (and so can't decide on) a good way to energise the relay after a second or so.

Does anyone know of a link to a reference implementation for such a circuit?

Cheers

Best Answer

I have seen, but cannot find again, a really simple implementation of a mains soft start circuit. The thing I'm thinking of involves a power resister inline of the mains. When the device is started, current is restricted until a relay is energised, which shorts out the resistor allowing full power

Something like this: -

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Or maybe like this: -

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Or just use one of these: -

enter image description here

It's a thermistor that when cold has a resistance of tens of ohms and rapidly warms down to a low on resistance but it's slow enough to take the edge of the inrush current.

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