Triac get burnt after driving 2 min 1.5kW resistive load

Asked Jan 22 '23 at 15:33

Active Jan 23 '23 at 19:30

Viewed 85 times

I am trying to drive a 1.5kW heating resistance using QJ6025LH5TP triac. Schematic and PCB layout.

So the thing is that my circuit is working for a while and I trying to measure the temperature from behind the PCB using an infrared thermometer. There is a significant temperature rising after 2 min resistance switch on and after a while triac get burnt completely.

Strange thing is that I have seen 3 different scenarios these are once R28 gate resistor is get burnt second MT1 and MT2 terminals got short circuit and R40,R14 got burnt. You may also see the heatsink that I am using which should be sufficient to drive 1.5kW load.

So it is most common triac driving circuit the only big difference is generally load is placed on MT2 side however in my configuration load is connected to MT1 terminal. but for optocoupler driving usage in should be okay. Waiting for your comments.

edited Jan 23 '23 at 19:30

StainlessSteelRat

7,851
2
18
34

asked Jan 22 '23 at 15:33

EdhelSoldier

You show neutral on both sides of the triac Also, make sure heatsink surface is clean, smooth, and thermally bonded to the device. – PStechPaul Jan 22 '23 at 20:25
I see you're uysing 600V parts, but what's the actual voltage - how many amps is 1.5kW? – Jasen Слава Україні Jan 23 '23 at 11:02
Expect around 2 W per Amp of load, your heatsink looks like 10-15W in open air. – Jens Jan 23 '23 at 12:58
@PStechPaul Neutral is the real neutral of the circuit oneutral is connected to the load so line is directly connected to load and other side of the load is connected to oneutral. – EdhelSoldier Jan 23 '23 at 14:47
@Jasen, working with 220V RMS grid so drawing around 7amps. – EdhelSoldier Jan 23 '23 at 14:47
@Jens i have another board that designed by someone else working with nearly the same heatsink however it is getting hot significantly slower than my triac. – EdhelSoldier Jan 23 '23 at 14:47
1

You should add your details in comments to the question. – StainlessSteelRat Jan 23 '23 at 19:32

Triac get burnt after driving 2 min 1.5kW resistive load

0 Answers0