2023-08-28 01:49 PM - last edited on 2023-08-31 12:31 AM by Peter BENSCH
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?
2023-08-28 02:10 PM
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 )
2023-08-30 09:40 AM
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.
2023-08-30 12:25 PM - edited 2023-08-30 12:26 PM
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.
2023-08-30 01:39 PM
2023-10-04 10:14 AM - edited 2023-10-04 11:13 AM
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.
2023-10-04 11:51 AM
2023-10-04 12:13 PM
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.
2023-10-10 10:18 AM
2023-10-10 10:39 AM
Mmmm . this is no good circuit for a triac . there are many couplers, to this job, ie. MOC3083 or similar.
with input current > 5mA (from your timer controlled circuit -> transistor out) this "MOCxxx" generates at zero crossing start pulse for triac - reliable. and low emission on mains...because zero crossing switching.
change your circuit...