Hello People;
I am trying drive 25uf capacitor with a optocoupler and triac. I have tried so many triacs and huge heatshinks, but always triacs goes fire because the high temperature on triac.
is there any advice
thanks from now on
regards

 

Please explain in more detail, and post a schematic of your arrangement.

I advise you not to try it again before finding out what is wrong, as it sounds dangerous - is the circuit connected to the mains?

 

Please explain in more detail, and post a schematic of your arrangement.

I advise you not to try it again before finding out what is wrong, as it sounds dangerous - is the circuit connected to the mains?

Dear Adjuster you can see my schematic on http://img163.imageshack.us/img163/6451/61125722.jpg or
kind regards

 

mesuthh,

you didn't fully answer the question about the supply voltage.

Your triac is probably failing due to exceeding a critical parameter value.

The single or repetitive peak current may be an issue. There are transient as well as steady state conditions to consider at the turn-on instant.

You might consider placing a limiting load resistance in series - such as an incandescent lamp - to make sure the basic function is what you intend.

What is the point of your experiment?

 

mesuthh,

you didn't fully answer the question about the supply voltage.

Your triac is probably failing due to exceeding a critical parameter value.

The single or repetitive peak current may be an issue. There are transient as well as steady state conditions to consider at the turn-on instant.

You might consider placing a limiting load resistance in series - such as an incandescent lamp - to make sure the basic function is what you intend.

What is the point of your experiment?

Your so kind.

I would have said, your shorting your supply out moron, your going to injure yourself or someone else.

 

Your so kind.

I would have said, your shorting your supply out moron, your going to injure yourself or someone else.

Dang....I couldn't have said it better !!!!!

 

mesuthh,

you didn't fully answer the question about the supply voltage.

Your triac is probably failing due to exceeding a critical parameter value.

The single or repetitive peak current may be an issue. There are transient as well as steady state conditions to consider at the turn-on instant.

You might consider placing a limiting load resistance in series - such as an incandescent lamp - to make sure the basic function is what you intend.

What is the point of your experiment?

dear Tnk I am trying to make a mini compansating
regards

 

just being lighthearted,

I am trying to make a mini compansating

if you squeeze afew more amps into that cap you'll make a maxi expansiator.

 

dear Tnk I am trying to make a mini compansating
regards

What is that??

 

That circuit is not going to "drive a capacitor", but demonstrate the sensitivity of a TRIAC to ΔV/ΔT and/or short circuit current.

What is the AC source? Is the capacitor rated for AC? Why is there no fuse present?

 

I would guess that this is an attempt at switching power factor correction capacitors. That is actually a pretty tough application: professional gear of this kind goes to some lengths to protect the switch elements. This circuit has no snubbing or other filter elements: apart from the inherent switching rate problems, any spikes or higher frequency cr*p on the mains input can come straight through the capacitor to get at the triac.

The drive to the input LED comes via another unspecified LED in series, so it's not clear how much drive it would get.

There may however be a far more basic problem. When the LED drive is removed, the triac will turn off when the capacitor current drops to zero. This is however on the peak of the input voltage, when the capacitor will be fully charged. When the input voltage reverses, the capacitor voltage will be added on to the next voltage peak, giving a total of about 678V for a 240V AC supply. This may be enough to break over the triac, in which case it will surely fail.

 

That circuit is not going to "drive a capacitor", but demonstrate the sensitivity of a TRIAC to ΔV/ΔT and/or short circuit current.

What is the AC source? Is the capacitor rated for AC? Why is there no fuse present?

dear beenthere;
AC is 240 V Ac.
regards

 

U need a load

 

You need to stop what your doing and take up a different hobby.

but always triacs goes fire because the high temperature on triac

First the fire, then God will speak to you in a soft, beckoning voice.

 

The circuit as posted is not going to work under any circumstances.

Perhaps the OP can explain what he means by "driving a capacitor", and why there are no fuses present.

 

dear beenthere;
AC is 240 V Ac.
regards

Then as far as I can see, the triac will definitely blow up. The problem is due to the phase lead of the current through the capacitor.

When the gate drive is removed, the triac will turn off at the next capacitor current zero-crossing. The supply voltage will actually be at or near its peak value, so the capacitor will be charged to near peak supply voltage. During the next half-cycle the capacitor voltage will add to the (opposite sign) next voltage peak, bringing the total to about 678V. The triac you mention is 400V maximum blocking, so it will will break down.

 

We don't even know if the cap is AC rated.

 

Perhaps it's an ordinary polarised electrolytic, with a nice strong can.

 

The OP isn't exactly a chatterbox in regards to answering questions. Personally, I think he's a statistic waiting to happen. I also see this thread as more hazardous than most automobile topics that are verboten on AAC.

 

I would agree about the danger. The questions have been to try to figure out what this is all about and perhaps save the OP from becoming a statistic.

We'll just close this very shortly unless the OP can say what is it that he is trying to do. A rather complete answer is expected.