Triac switching heating element

Projects General Guidance
1

So, after searching around , ive seen that quite a lot of AC devices are utilizing Triacs to switch on and off heating elements, Solenoids, Motors, Fans etc.

Since i want to controll the heating element of 1200watt with a microcontroller i need to connect low 5vdc voltage to 230vac mains. That means a optocoupler.

MCU GPIOs can be easily overloaded so i need to mitigate that with a BC337.

So this is the schematic that i am planning to use.

I have seen that the Sage Breville espresso machine is using the BTA16-600 with a moc3063 .
Its still in the plaing table but i will still have to work it out if i use the moc3052 or the moc3063 but i will probably go with the moc3063 since it is already proven by many devices.

So the idea is to PID the heating element via a 2040zero that drives a BC337-moc30xx-BTA16-600CRG .

I believe the schematic should be correct as shown below.
It has a snubber RC a MOV and a fuse. Is there anything that can be more safer than this ?

Cheers in advance.

PS : I already have SSR purchaced (i dissed the foteks, got my self some RSS-TD1A125ZP: DC Input AC Output 25A Solid State Relay : Selec
I just want to make my own Triac Board since i will need 9 triac circuits.

image
image1508×585 42.2 KB

image
image724×507 116 KB

2

Maybe I am misunderstanding you but I made a similar thing using just 1 SSR. 5VDC from a NANO to turn on/off an AC Mains circuit

2 Likes
3

I will make a board, with 3x mcu which will drive 3 or 4 of those triac circuits.
I need total 9 triac circuits.

So if this is a safe and correct circuit, i will make my own pcb .

The question is
A) is the circuit correct ?
B) is there anything i missed out regarding safety ?
C) Is there anything that can be more safer than this ? (your answer is SSR)

that is true, but it wont be DIY any more and its no fun and satisfaction of creating something.

4

There are inexpensive triac modules around, in case building from scratch is not objective.
https://aliexpress.com/item/32802025086.html

1 Like
5

Good luck.

6

Your schematic looks OK to me. I've built similar circuits with different opto-isolators (MOC3042) and different TRIACS (I don't remember the part number). I built my own because solid state relays were too bulky for my application.

I didn't include the snubbing network since I don't have an inductive load, and I didn't add a fuse or MOV.

You'll probably need heatsinks for the TRIACs.

1 Like
7

I think the fuse should be the first element in the line input to the circuit.

1 Like
8

exactly, will do. This is what i am thinkin of.

image
image388×274 47.7 KB

I will use it for inductive and resistive.

9

Ah yes, that is correct. I will do that immidiatelly.

10

Note that the metal tab of a triac is live (connected to mains power).
You need special (high voltage) isolation washers and mounting screws to prevent the whole heatsink going live. Not a safe task for a beginner. Better find a smaller SSR.
There are 5A or 6A "slim SSR" modules, to mount on a circuit board.
Leo..

176698
176698200×200 8.43 KB

1 Like
11

Great detail. That was one that almost got me when i was searching for those triacs.

There were some BTA16's that i wanted to buy, but they were not insulated. They had low IGTmA triggering but i didnt chose them due to the non-insulation.

I have the BTA16-600CRG and at the datasheet it says :

image
image648×267 35.3 KB

It was the first thing i checked when the triac arrived :smiley: :laughing:

12

I was indeed eyeing this and the sharp and the panasonic.

Allas i have a 1200watt 230vac which is like 5.21A and those pcb SSR's are 6A so, they dont give me much peak current headroom.

That is why i was looking at the BT41-600 triac. But it doesnt matter that much 16A-41A rated.

Heating dissipation will be almost the same or very little difference. (between BT41-600 and BTA16-600) .

13

Hi, @jimhard2learn

What is you project that needs 3 MCU and 9 triac circuits?

Tom.... :smiley: :+1: :coffee: :australia:

14

Steam boiler, Brew boiler, Pre-heat boiler, 2 pumps, 2 fill in solenoids, 4 NTC's , 1 loadcell, 1 flowmeter, touch screen, leds, water tank level sensor, diffrent bar solenoids pre-infusion and brewing. xD

15

A single Mega should do all of that.
Multiple MCUs can cause inter comunication and phantom powering problems.
Leo..

16

Those are very different loads. Heating resistors don't require phase cut approach, but pumps likely do. And while triac dimming is fine with "universal motors", it's not so universal after all.

17

I am hoping that with the master slave rx/tx coms and dividing the calculation capability to balance that problem.

18

Correct, resistive AND induction loads, that is why i am going to probably use moc3063 and moc3052 but that is still to be decided yet.

19

i also going to use 2040zero so calculation capacity RAM etc are faster and biger than the Arduino Mega. I did liked those expansion shields but the specs are too atractive to leave :slight_smile:

20

Resistive loads don't need phase cutting on your application and thereon neither MCU resources. Pumps are different story if you try to regulate the speed. Did you ever try they accept leading edge control?