Thank guys for your replies .Some of them i have to study first

Let me make some things clear about the circuit and values chosen

1. I've measured turn-on , turn-off delay at 3.3 ms for the driver relay.All
results are
after calculating this delay .So what is see on the scope is at the moment
i'm explaining
2. the arc is across the driver relay .The power board is inside a control
unit box so
i have to leave with small distances and cpu disturbances.Its actually a
microcontroller
having the problem .Driver relay contact current rating is 5A at 220V
.Power relay coil is rated is 6
watts consumption at 220V.
3. Using large value capacitors over 33 nf was causing sometimes latch of
the power relay so i have
value limitation here
4. The capacitors i've chosen are X2 self healing 275VAC. With no ZC control
they are blown
to 0 nf value (some of them) after 10-12 months of operation.
5. I don't have the space or budget to use large sized capacitors rated at
higher voltages or SSR .
The idea was to use ZC to avoid using expensive and large size protection
snubber
So the question is .

Does the relay On/OFF time differs with time .If it's 10% it's not a
problem since again
the arc will not be so high .Since its the current break that causes the
arc i must switch off at Peak of the
ac voltage .This is what my reading confirmed .In this case switching a
resistive load must i change the driver
algorithm ???

Any helpful comments will be apreciated



The circuit below simulates fairly well. You don't want to use a
conventional snubber across the contacts because on opening the relay
coil voltage reverses and adds to the 220VAC source. Placing a snubber
in shunt with the coil with peak current limiting resistor as shown
increases operating power by about 10% but tends to maintain the contact
voltage and results in a very slew rate limited 0.5V/us contact voltage
peaking in the 450V range. There should be no arc at all with this
circuit, with or without zero crossing logic. K1 are the 12V relay
contacts and K2 is the 220VAC coil. I did not consider contact bounce on
closure, will leave that to you.
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