Triac ?

[tekman11]

Hi all,

For a AC power (220vac) show a triac placed  on the high side.
Can it be used on both high and  low side of the AC?

Thanks

[Zero999]

It depends on the circuit. Generally the switched is placed on the high side.

[T3sl4co1l]

It's noteworthy that, in the US, both lines are hot, so it doesn't matter.  The consequence is, even when the switch is off, you must still treat both lines as potentially hazardous -- because they are!

Tim

[tekman11]

It depends on the circuit. Generally the switched is placed on the high side.

In reference to earth gnd.

208vac, both lines(L1 and L2) are hot a triac conducts in both directions, should work
120vac(USA power), the neutral and earth ground are at the same potential, is where I'm stuck

thanks

[MrAl]

It depends on the circuit. Generally the switched is placed on the high side.

In reference to earth gnd.

208vac, both lines(L1 and L2) are hot a triac conducts in both directions, should work
120vac(USA power), the neutral and earth ground are at the same potential, is where I'm stuck

thanks

Hi,

I would connect MT1 to neutral and use MT2 for the load.  That way the gate common also connects to neutral.
The load connects between the 'not' and MT2.

However, you can not always trust the wiring in the house or other because sometimes the black and white (hot and neutral) wires are switched inside the electrical outlet box.  This means MT1 might get connected to the 'hot' wire in some cases.
The wiring accuracy has gotten better over the years as everyone starts to understand this better and with the introduction of the three wire and two wire plugs with wider and more narrow prongs, but there is still the possibility of a swap inside the box.
If you need to test for this with your circuit, test for voltage between the supposed 'hot' wire and neutral wire which should show the full line voltage, and from the other wire (white usually) to neutral which should slow only a small voltage or zero.

[madires]

...and take care about Q4 operation mode. Some TRIACs can't be triggered in Q4.

[T3sl4co1l]

...and take care about Q4 operation mode. Some TRIACs can't be triggered in Q4.

Yes.  No worries if you're going to use something like the usual MOC3011 or whatever, standard circuit, of course.

Tim

[David Hess]

It's noteworthy that, in the US, both lines are hot, so it doesn't matter.  The consequence is, even when the switch is off, you must still treat both lines as potentially hazardous -- because they are!

Tim

All of the US wiring I have worked with is split phase 240 VAC so there are two hots and a neutral with any 120 VAC circuit having one of the hots and the neutral.  Mis-wiring happens of course with hot and neutral swapped so devices should be designed to handle that.

[tekman11]

Hi,
[/quote]
I would connect MT1 to neutral and use MT2 for the load.  That way the gate common also connects to neutral.
The load connects between the 'not' and MT2.

[/quote]

A triac would be placed above and below the load,  the gate common for the triac above the load would not be connected to
neutral. Is this a problem?

[MrAl]

Hello,

If you mean you are connecting the load between 'hot' and MT2 that sounds right.
MT1 then goes to neutral.  Gate pulse between gate and MT1.

I dont know what you mean by, "the triac goes above and below the load".  Do you mean you are using two triacs?

[tekman11]

Hello,

If you mean you are connecting the load between 'hot' and MT2 that sounds right.
MT1 then goes to neutral.  Gate pulse between gate and MT1.

I dont know what you mean by, "the triac goes above and below the load".  Do you mean you are using two triacs?

the plan is to use 2 triac's  one above and below the load. is it mandatory that MT2 be connected to the load  when switching neutral (load connected to hot, when off)?

thanks
 

[Zero999]

Hello,

If you mean you are connecting the load between 'hot' and MT2 that sounds right.
MT1 then goes to neutral.  Gate pulse between gate and MT1.

I dont know what you mean by, "the triac goes above and below the load".  Do you mean you are using two triacs?

the plan is to use 2 triac's  one above and below the load. is it mandatory that MT2 be connected to the load  when switching neutral (load connected to hot, when off)?

thanks

Why?

I hope you're aware that TRIACs are not an effective way to isolate a circuit and protect against electric shock? They tend to fail short circuit and have a nasty habit of being turned on by EMI.

[dannyf]

For a AC power (220vac) show a triac placed  on the high side.

Since it is AC, there is no "high side" or "low side".