Bouncing time of mains contactor?

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treez

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Hello,
We will use a contactor to switch our circuit on and off every second at mains (230vac) peak to note its resilience to inrush.
Do you know what is the bouncing time of a typical contactor? say one of the ~£20 ones.
Our circuit draws only 600mA RMS, however, due to the two 100n x2 capacitors, there is an inrush caused at mains peak, decaying sinusoid ring of peak 50Amps. Its decayed away after some 60us.....the period of the ring about 7us.

They dont seem to give the bounce time...

https://www.tlc-direct.co.uk/Produc...=finalurl_v2&gclid=CPLn9q7Wy9QCFegp0wodEUkBAw

https://www.schneider-electric.com/...t-subcategory-id=1510&parent-category-id=1500
 
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Hi,

This is a mechanical relay. For sure it needs some time to switch ON/OFF. 20ms is a common value for such relays. (I'd even say it's rather fast)

Switch ON:
* apply voltage to the coils
* current rises relatively slowly due to coil inductance
* at a certain current level the contacts start to move. Here you have mechanical inertia that makes it slow
* then the contact touches for the first time..now bouncing begins
* bouncing ends. Stable ON condition.

The time from applying voltage to stable ON condition varies a lot. It depends on (with same relay type):
* applied voltage and it's waveform
* temperature
* age
* switching cycles
* OFF time
* mechanical vibration
* dirt
* mounting position
*...

I'd say it is impossible to switch a load ON (somhow precise) at peak mains voltage.

Use a triac instead.

Klaus
 
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or maybe instead of finding the peak of the sine wave, use a square wave instead, you get an inrush at every cycle that way. For testing your circuits you can probably use a low frequency switched from a ~340V DC supply, maybe 10Hz or less.

Hint: generating 340V DC (peak sine 240V RMS) is rather easy as long as you are careful with safety isolation.

Brian.
 
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