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relay / zero crossing problem

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baba_sanfur

New Member
Hi,
I would like to switch on/off relay for 16A(rms), voltage of 230v. the switching must take action as close as possible to the zero-crossing point. I cannot use SCR relays, because of the price / heat.

So I build a simple relay driver – using transistor. The problem is that all simple relays (the cheap relays..) have tolerance of 10-20 ms operation time.
I built a zero – crossing detector and it works great – but since the tolerance of the relay is >10ms, ant the line frequency is 50hz (20ms), all the design is useless.

I have two questions:
1. How can I reduce the time to operate the relay, or at least stable it to constant value?
2. Is it possible to put protection element (like move) in parallel to the output pins of the relay, to protect the appliance from spikes (if the zero cross detection doesn’t work properly)

Thanks,
Nir
 
Hi,
I would like to switch on/off relay for 16A(rms), voltage of 230v. the switching must take action as close as possible to the zero-crossing point. I cannot use SCR relays, because of the price / heat.

So I build a simple relay driver – using transistor. The problem is that all simple relays (the cheap relays..) have tolerance of 10-20 ms operation time.
I built a zero – crossing detector and it works great – but since the tolerance of the relay is >10ms, ant the line frequency is 50hz (20ms), all the design is useless.

I have two questions:
1. How can I reduce the time to operate the relay, or at least stable it to constant value?
2. Is it possible to put protection element (like move) in parallel to the output pins of the relay, to protect the appliance from spikes (if the zero cross detection doesn’t work properly)

Thanks,
Nir

This is a double post.:)
 
Find a Zero Crossing Triac.
 
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