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Is Triac reliable as replacement for Relay for 220V multiteapped Transformer?

20 years ago I've successfully designed and built a 5 relay Automatic Voltage Regulator for household use appliances and computers. But I did not market it because relay switching was noisy and annoying.

Now I want to replace 5 Relays into Triac for faster and noiseless voltage selection or switching the multi tapped transformer.

It seems triac will have problem on switching inductive load such as electric fan or motor driven appliances.

I just want to know if there's new technology triac that will be immune to these "electrical noise during switching of triac? .:)
 
Last edited:

Harald Kapp

Moderator
Moderator
Triac technology has advanced, but the principles have not changed. You will have to add snubbers to your triacs to prevent them from switch on dv/dt.
 
Thanks Harald.
I'm not really a graduated electronic engineer. But I've have long years in analog and digital electronics and already have experienced with Triac SCR and Diac. But never designed circuit using these components. That's why I asked this questions.

Just another question. Mostly household AC outlet here in Philippines does not follow the standard 2 prong AC 220V outlet which have keyed hole for "live" line and neutral line. Would it be affect reliability of AVR using Triac circuit if the AC plug was inserted other way around? i.e. the neutral plug was inserted to live line and vice versa.

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Harald Kapp

Moderator
Moderator
Neutral and phase is just a convention (besides neutral normally being grounded). From the point of view of an attached circuit there are just two wires leading AC.

Things change once a part of the circuit is grounded by any other means. Then a fault current may flow if the connector is plugged wrongly into the mains outlet. But that situation should be prevented anyway. I suggest you provide isolation between the controlling circuit and the mains circuit. You can use e.g. an optical isolation.
 
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