Hello everyone, I am trying to develop a small solution for soft switching power capacitors.

I will share some background on the solution required.
In our power control panels we have power capacitors of 100 Kvar i.e. 25Kvar x 4 Nos for power factor correction.

We are using special capacitor contactors from Merlin Gerin, but we have observed 'sometimes' due to high in rush currents when all four are switched ON simultaneously these contactors give way.

The solution to this problem is switching each one after a certain time delay.

I was planning to use LPC922 for this and have triacs (BT136)at output to turn ON 230V AC coils of the contactor after some time duration.

Now the coming to issue, recently in one of our developments I have seen the relay beign ON even when I had turned off the Triac, we solved this by putting a 40W bulb in parallel to coil, though this problem was solved I cannot do the same in this application.

Now I am in a dilema should I use a relay ( which does not have a predicatble turn On time) or use a triac.

I will not be able to use expensive snubber as it is cost sensitive and cannot wait for a long time for RS to quote and deliver.

SSRs at Rs.200 are out of question.

So how do I solve the issue in these limitations.

Thanking you

Deepak