OK thanks everyone. Attached i have my new design. What do you guys think?
Hi,
I think a snubber would be a good idea, as well as zero cross switching.
Also, i see you have a 16 amp triac spec'd on your drawing. If you can get a higher current rated triac for almost the same price, i'd go with the higher rated part as long as it does not impact the total cost too much. If this is a one-off project though, i would not hesitate to spend twice as much or even more for a higher current triac knowing that i will be getting a more hardy part to start with. If this project is that important to you, do it justice by getting good parts that can stand up to the current and voltage demand and doing the design as close as possible to recommendations by manufacturers who make the parts. Often you can find recommended designs for these parts. In other words, do everything possible that makes the design better. Once you do everything possible you should get a good working system or else the very concept of doing it that way is somehow flawed.
It also does not hurt to roll your sleeves up and get in there with a good scope. Heck, even a not so good scope
In power designs of any kind (those that deal with line voltages and/or creating power supply like voltages and currents) there is no chance in heck that a manufacturer of a power system will allow that system to go out the door without some rigorous testing. That testing would included looking at waveshapes during the complete operation of the device, which includes various things like looking for over current surges and looking for over voltage spikes. Once it is found that the transient behavior is acceptable, the system would then go on a life test which could be as simple as an overnight non stop run at the full current rating of the system.
I am telling you this because just building a system that looks like it should work is never enough...it has to be tested and known issues are searched out to find out if there could be a problem before it happens. That's mostly because some design flaws do not show up right away but take time to progress, and some fail right away and it's hard to know why without looking at the waveforms in various places in the system. For example, if you see a 600v spike across a 600v device, you know there is a good chance it's going to fail sooner or later. The design schematic may not tell you that though, you need to look at that with a scope. That gives you the confirmation of everything you thought was true is true or is not true in the theory of operation.
What this means is if you still have problems after this, you should get a scope and start looking for problems before they happen. This may involve trying to operate at a lower voltage so that nothing blows right away, if the failure happens soon after turn on. Sometimes that is not possible but if you can make that happen you have a better chance of finding the problem. I dont know if you have a scope though, or can get one somewhere for this.