sht75 code locked up

[mister_e]

I don't see how it could be done if you just have 1 contactor to do the job... but with 3 .. no problem, fire them on each zero crossing should work.

I know there's some dedicated contactor for that. Google search i guess.

Melanie should have some pointer on that.

As i'm not in a familiar area... i can't be too much of help.

[microkam]

thank you mister very much again.

but realy i dont know if any body can help me in this point .

[Melanie]

MisterE - you can't fire a Contactor on Zero-Cross (well you can but it won't do you much good)... think about it, by the time the contacts close, the mechanical lag involved means zero-cross has long gone... and firing the contactor coil at zero cross does a heap of good... a 10W coil is really important when compared with a few kW of Heater...

Hmmm... since I have several commerical Three-Phase Heating Controllers on the market, I have to tread carefully...

Firstly, you only need to control TWO out of the three phases (although all three should be fused/protected).

The easiest (though not the cheapest) solution is to use a zero-cross SSR in two of the phases. All you do is treat the SSR input as if it was an LED. Switch it on, and it does the rest. You will find that Crydom, Carlo Gavazzi (and others) all do Zero-Cross and non-Zero-Cross versions of all their SSR's. Like I said, chose a Zero-Cross version.

The alternative is to use an opto-isolated "Zero-Cross Triac Driver" to fire your main Triac (which is what I tend to do). An Internet Search will provide you with heaps... MOC3061, MOC3062, TD3043... again treat it as an LED... Don't forget you need one in each of two phases.

NEVER EVER hang your PIC in a non-isolated circuit when playing with three-phase power. Trust me, you will die - and worst of all you then won't be able to come back and tell us, so I won't be able to say "I told you so!".

[mister_e]

Yeah i knew about the Contactor latency and i stated it on post #5.

I'd never drived any 3 phase stuff. Even never used any SSR. For all my AC control i use Triac and, of course the Opto-Isolator (zero cross or not depending the day). Yeah also love the KV of insulation.. same for the power supply... never EVER use transformerless.

Now our friend have more than enough information to solve the problem.

[microkam]

thanks all again>
i tryed to put EMI filter on main control supply, but the problem still there, i supplied PIC through shotky diod and put many 100nF capacitor and nothing changed >

NEVER EVER hang your PIC in a non-isolated circuit when playing with three-phase power

what do you mean in a non-isolated circuit ??
between my PIC and contacter there is an opto-coupler and small relay , the power supply of (opto-coubler transister) is different for my pic power supply with different transformer and different GND , is this the isolation you mean !!

is the noise from heater contacter make all the problem through main supply or through air to the board ??

if i take the board supply (220v) from another location and didnt connect it with the same heater supply will solve this noise problem ???

[microkam]

hi Melanie

The easiest (though not the cheapest) solution is to use a zero-cross SSR in two of the phases. All you do is treat the SSR input as if it was an LED. Switch it on, and it does the rest. You will find that Crydom, Carlo Gavazzi (and others) all do Zero-Cross and non-Zero-Cross versions of all their SSR's. Like I said, chose a Zero-Cross version.

i search for this SSR in my country and it's not avilable and it takes over one monthe if i order it..

so can you explain to me whats exactly the source of this noise!!
if i seperate control board and power contactor in different panel will reduce the noise >>>

[Melanie]

>so can you explain to me whats exactly the source of this noise!!

The meaning of Life, the Universe and Everything I can probably explain. The source of your noise however escapes me. I'm not in your environment, I can't see your design, and I have no test equipment available to track it down - this is something that you can do - because you are there, and I am here.

I worry about the code that you posted where you say the problem exists. Your While/Wend statements will hang the program until the correct state of the dta pin is recognised. You must track down WHICH of the several WHILE/WENDS is causing your program to hang and then determine WHY dta did not switch as expected. Is it because the PULSEOUT is out of specification and the chip did not acknoledge. Is it because noise on the line is causing the chip to acknowledge at the wrong time or send garbage. You'll have to dig deeper yourself.

It's unusual for the DS1307 to hang... I have tens of thousands in the field and it's never happened. Check your 5v supply is CLEAN. Make sure the Battery isn't next to a contactor switcing kVA - the usual things...