Can I use a Triac instead of Relay for my purpose?

[rrlamichhane]

I'm constructing a circuit which conducts 'line A' when '24' DC voltage is applied to Relay and conducts 'line B' when the DC voltage is absent. The switching speed is not that significant and Relay would do the job. This can be very easily accomplished by the use of Relay, I know that. But would Triac be more durable than Relay. I circuit will need to conducts at least 10A in 230V AC.

What would be the advantages of Triac if it can be used in this circuit without impairing its functionalities? Also, which Triac would be most suitable for this purpose?

 

[nandhu015]

Yes Triac is best.

Check out this link



Nandhu

 

[rrlamichhane]

Yes Triac is best.

Check out this link



Nandhu

no no, Opto-triac is too much for my circuit, it's just a really simple circuit and I want to make it cheaply. I am just asking that can i just replace the relay with Triac and will the circuit work as before? I have attached the simple schematic.

 

[cameo_2007]

It depends on how you are controlling that 12V to the coil of the relay.
Note: In your post above you have mentioned 24V and in the drawing it is 12V.

It looks like the RELAY is the best option for you.
Make sure you choose the right part. 230V/10-16A

 

[betwixt]

It isn't quite as simple as that but a Triac is still the best solution and in view of the high current you are carrying, probably the cheapest as well.

The trouble with just using the 12V is that in the case of a Triac, it has to be connected between two of the three terminals and these are of course carrying 230V AC. So unless you were exceptionally careful, your 12V supply would be made live as well. Using the same 12V would also imply the two sides of the switch were linked together which is probably not what you want.

The opto-Triac solution is very simple, you only need a few inexpensive extra components and your control voltage is fully isolated and safe. You also use significantly less power from the 12V to do the switching, perhaps 100mA down to 10mA.

Brian.

 

[cameo_2007]

Won't you require a zero crossing detector,if using a triac ?

 

[FvM]

I won't say, that the circuit is particularly terrible. It's completely unclear. Assuming the said 24 V is a controlling voltage, what's the purpose of the 12V supply? Where is the said 230V circuit?

You can use a triac as simple switch, if
- you don't need isolation between the control circuit and the 230V circuit. Connecting the control circuit to the triac directly means,
that it's becoming part of the high voltage circuit, that must be protected by safe isolation.
- if the load is AC, not DC
- if you provide a sufficient heatsink for the triac power dissipation at 10 A
- if the load isn't inductive, otherwise you need snubber additional circuits
- if you're sure, that no inrush currents can damage the triac

Considering the short list of restrictions (there are probably some more), it can be a good idea to use a mechanical relay. Most
home appliances actually do for high current switching, if the switching frequency is moderate.

To comment another post. Zero cross switching is not absolutely required, unless switching very often. A relay also doesn't use zero
cross switching. But's it's desirable of course, and can be simply achieved in many cases. With inductive load, it's generally unwanted, in contrast.

 

[rrlamichhane]

OK guyz, heres a proper circuit figure. This circuit is intended to 'short circuit' the 'AC power mains' while there is voltage on the AC line and 'open circuit' the inverter line' at that time. If the 'main line' goes out then it will 'short circuit' the 'inverter line' to destination and 'open circuit' the AC main line. The 24V DC is generated from 'main ac line' so it can be used to control which line get's 'short circuited' and which one gets 'open circuited'.

I know, it's really easy using the Mechanical Relay, but I want to use a 'Triac' and also can you guyz tell me what are the advantages of using Triac over Relay on this purpose? And also which one is more durable?