T810-600B-TR TRIAC Not Turning ON With Load

[PDIhawk]

I have a legacy project that I converted to an SMT design but the existing TRIAC is not meeting all specifications of the product. I am evaluating other options and one option that I'm looking at is the T810-600B-TR. In this application, the transistor is fully turned ON and passes 120VAC for up to 12ish minutes, then turns OFF. I have played around and can't get this part to fully turn on under load. The gate is drawing 14mA, gate voltage is 0.9V but the output is only 62VAC under a 500W load.  However, when there is no load, the output is 117VAC.

Why wouldn't I be able to get this part to pass all of the input when it is under load?

[AScha.3]

make a DSO pic, trace 1 : gate current , trace 2: anode voltage. to see, when and how much gate current is at the triac. (2x , pos and neg trigger )

[PDIhawk]

Unfortunately I don't have an isolation transformer yet.  So I'm not able to measure the Vout with the scope.  The best I was able to do with the equipment I have was to log a couple of hand held DMMs that have isolated serial ports, then plot the data in excel.  It is very strange though because the Vout jumps up beyond the VAC rating but that must have been some weird glitch.  I have the graph that I generated from the data attached.

[AScha.3]

you made a nice picture, but no scale, no value, so sorry, but talking about pictures will help nobody.

if you cannot make any real time measurement, nothing real to talk about.

[PDIhawk]

I apologize for not including scales and legends.

I have fixed up the picture and added my xlsx.

[PDIhawk]

Ok, I picked up an isolation transformer and grabbed some real time captures on the DSO.

Under load, the top half of the sine wave doesn't get passed.

Edit:

Nevermind...  Removed pictures, I need to go back to get new measurements.  I see that AC is passing regardless of gate drive.

[PDIhawk]

Ok, so now I really don't know what is going on.

I thought my measurement method was wrong but it is correct.  Without gate drive, it is actually passing AC.  It even fully runs the 500W load.

Here are my DSO captures again

[AScha.3]

show circuit . and where your test points are, for trace 1 + 2 .

somewhere is a cap at the gate/trigger drive , that shifts dc level for trigger. 

[PDIhawk]

Here is the schematic with the locations of the Oscope probes.

There is no cap to shift the DC level for trigger but there is a revision coming up that I could add one if necessary.

Thank you for your help!

[PDIhawk]

Ok, after absorbing this problem more, I think that this circuit isn't that flawed because I don't really need to worry about zero cross switching and this works with a different TRIAC.  This circuit turns the TRIAC ON at power up and once the timer has lapsed, the TRIAC is supposed to shut OFF.  The only point that the zero cross would come into effect is at the start and end because it isn't periodically turning it on and off during operation.

[AScha.3]

right. :)

but the MOCxxx triac driver giving a good trigger pulse to the triac , thats the point!

[PDIhawk]

I'm understanding this even more now and see what you are talking about.  I will be implementing a zero-crossing circuit to control the gate.

The only thing that I still don't understand is why the L6008 TRIAC works as long as I don't run it at full load.

[PDIhawk]

For an update:

I want to avoid single source parts, so I implemented a simple zero-crossing circuit using a bridge rectifier and opto as attached.

This still didn't get my device to operate using the T810-600B.

To get this project moving forward, I reverted back from the STmicro part to the L6008 TRIAC. My main problem with the L6008 was that it was just overheating under load. With a better heatsinking design, I was able to get the L6008 working without zero-crossing.