Choosing a triac - power regulation?

[Spoerle]

I need to regulate the power of the heating elements.
In the first case 3 x 230V 3x4kW
In the second case 1 x 230V 3x400W.

In both cases, it is a resistance heater with regulation to the target temperature and the rate of temperature change over time.
In principle, On/Off regulation or regulation with half-wave skipping would be sufficient.
On the other hand, I'm thinking of making a universal module with 3x triacs controlled by an optotriac plus a ZCD with an optocoupler and a small MCU that will control three independent regulators 0-100%, perhaps based on a request for UART or PWM.

According to the HW page, it's probably simple, MOC3053M snubbler for optotric and snubbler for triac. Precise ZCD with optocoupler and low consumption.

I have experience with triacs, but they froze somewhere over 25 years in the BTA 12,16,25/26,40/41 series. So I tend to use a 25 or 40A triac even for 4kW and 400W heating too.
Question, has the development of triacs moved somewhere and are there any better ones on the market, perhaps with lower losses or something?

Thanks

 

[KlausST]

Hi,

I dont see much of an development in triacs over the last decades.

Phase angle regulation: Be sure to comply with your local regulations. Pahse angle control may be restricted.
Full wave control - is timing allows - is preferred.

Maybe you can use a 3 phase solid state relay. Then all the zero cross and isolation is done already.


Klaus

 

[cupoftea]

@Spoerle, The cycle skipping is not allowed unfortunately...

Regulating temperature of mains connected heating element: Skipping mains half cycles

Hello, We have an electric heating element connected to the mains. We wish to regulate the temperature by skipping half mains cycles, as in the attached waveform (LTspice sim also attached). The power factor is great because mains current and voltage are always in phase. But is there any problem...

www.edaboard.com

But for the case of three coils on the same phase......you can effectively half cycle skip.......since the others can be conducting whilst one is skipped_out......so this may well be a good way for you.

As well as leading or trailing edge, you can also do both leading edge and trailing edge together, symetrically, so that you still get a reasonable power factor. So for this you would use a back-to-back IGBT and switch it depending on delays from your Zerocross detector micro/cct.

 

[johncaroline]

I need to regulate the power of the heating elements.
In the first case 3 x 230V 3x4kW
In the second case 1 x 230V 3x400W.

In both cases, it is a resistance heater with regulation to the target temperature and the rate of temperature change over time.
In principle, On/Off regulation or regulation with half-wave skipping would be sufficient.
On the other hand, I'm thinking of making a universal module with 3x triacs controlled by an optotriac plus a ZCD with an optocoupler and a small MCU that will control three independent regulators 0-100%, perhaps based on a request for UART or PWM.

According to the HW page, it's probably simple, MOC3053M snubbler for optotric and snubbler for triac. Precise ZCD with optocoupler and low consumption.

I have experience with triacs, but they froze somewhere over 25 years in the BTA 12,16,25/26,40/41 series. So I tend to use a 25 or 40A triac even for 4kW and 400W heating too.
Question, has the development of triacs moved somewhere and are there any better ones on the market, perhaps with lower losses or something?

Thanks

Your plan sounds solid! Triacs haven’t changed drastically, but newer models like BTA24/25/41 still work well. If you're looking for lower losses, consider using logic-level gate triacs or IGBTs for efficiency. Also, snubberless triacs like the ST T series (T2550, T4050) could help simplify design. Your MCU-controlled approach with ZCD is a great way to go for precise control!

 

[FvM]

It's quite clear that heater control has to use full wave switching to comply with EMC rules. It's a side problem if well balanced half waves (canceling DC) are legal under circumstances, but I don't see significant advantage over full waves, thus I don't address it here.

In addition to generation of grid harmonics, flicker effects must considered, particularly for high heater power. The old thread linked in post #3 gives some pointers.

Conduction losses of SCRs and triacs are almost fixed by forward voltage. Switching more than a few amperes requires heat sinks.