Switching on/off devices with Triac+relay

[Zedman]

triac relay

I would like to turn on / off a couple of devices (TV, HiFi) etc with a Triac + Relay combo.
The triac will turn on at zero cross, after that a parallel relay will turn on and after a small time triac will not be triggered anymore.

Same way when turning it off.

I read that there can be problems switching inductive loads with triacs.
This on/off event is going to happen just 0-20 times a day.

Do I need any extra precaution / snubber RC etc, to switch these appliances safely?

thanks,
Zedman

 

[cameo_2007]

triac switching

may i know what your exact logic,with a pictorial representation if possible.
does both triac and relay needed for such a switching application.?

 

[Zedman]

triac or relay

It's quiet simple scenario, just a bistable relay in parallel with a triac. I would like to use the triac to prevent the relay switching on in the middle of a sine wave.
But after that I don't want to use the triac because the relay is bistable and needs no energy to hold the ON state.

thanks,
Zedman

 

[pranam77]

on off con triacs

I guess there will be no problem as you are switching the loads with both the triac and the relay in parellel. The switching of inductive load is a problem with triacs only when you try to control the inductive equipment (Vary the speed for Eg). If you are switching the load On/Off only, i think no problems will be faced. But as a matter of safety for EMI and RFI, use snubbers and MOV's. Hope this helps you. Dont forget the "Helped me" Button. Good luck.

 

[wade_hassler]

triac relays

A triac in parallel with a latching relay will assure that the switch is made at a zero-crossing, but the triac must remain energized until the relay contacts are closed.
A TYCO KUL-type latching relay claims an an operating time of 25 mSec max, so the triac needs at least two cycles of gate-drive.

Wade Hassler

 

[Zedman]

triac as relay

thanks, I am using a Schrack PE014A05 relay, the switching sequence looks like this:

1) Triac ON
2) wait 50 ms
3) Relay coil ON
4) wait 50 ms
5) Relay coil OFF // by this time the relay has switched it's state
6) wait 50 ms
7) Triac OFF

 

[cameo_2007]

triac and relay

circuit please,if you dont mind

 

[Zedman]

triacs relay

Something like this:

 

[r2d2droids]

relay control with triacs

seems it doesnt create any problem.
have fun...