Boiler power control

[Dr. Dextrin]

I think it should work either way around (and in the live or the neutral wire) so it shouldn't be possible to connect it wrongly. It should handle 240V easily too - if it's like mine the triac is rated at 700V.

Definitely sounds like yours has died, though. Where did the spark come from? Did you short the output by accident? Have you checked the fuse?

[Hogarth]

Hogarth, how did you wire up the 3800w Ebay dimmer? it has just two connectors, Presumably whether the live or neutral is connected it doesn't matter? But which side is input vs output?i tried live in via the connector closest to the scr/heatsink, it worked for a few seconds then a bright spark and now nothing no matter which way or which wires I connect!

It says 220v only, whilst my supply is 240v so wonder if that's an issue?

The whole thing feels a bit unsafe so I might have to opt for a £50 site transformer if nobody has any other suggestions?

Hi Runthangs, actually mine was a phase angle controller from Farnell with five connections: live and neutral in, live and neutral out, and earth. So nice and easy. If you're looking for a £50 job I'd certainly recommend it. Sorry to hear about your spark, doesn't sound good.

[runthangs]

I gave it another go, and it still works, however the spark I mentioned occurred again. I have a very thick wire connected from the pcb connector to the immersion, and its the solder around the pcb that keeps burning. There's almost no solder left.

The live wire I used from the Mains is thinner (cut off from an iron), and hasnt burnt away the solder.

Is that normal?

I will try a thinner wire but now theres almost now solder/metal left on the pcb for the Mains in.

[Kev888]

Hi,
No, that doesn't sound normal.. sparks will usually be caused by having to bridge a poor connection or conductor, or by shorting out to something thats got too close. If its happening at the PCB and you have very little solder, I'd 'guess' it may be a dodgy/dry solder joint - though obviously its difficult to tell without seeing it up close.

If so, it will generate heat as well as sparks, and is likely to get worse as a result so I would advise not using it until its resolved. It could be caused by a manufacturing error or by having damaged it in some way - such as having drawn much more then the recomended current at some point (e.g. by shorting the output briefly).

Regards
Kev

[runthangs]

I sorted it by running some wire over the burnt out joints, it has been running fine today, but I don't keep it on for more than 20mins without a short break because the small heatsink get's very hot.

I have found my old soldering iron and solder so will solder the wire on properly, also have found a long slab of aluminium to extend the heatsink with.

Weird thing I found is that the solar pv inverter buzzes a lot louder now when the triac is running (which also hums a lot) vs when the triac isn't on. Normally the inverter buzzes more when the sun gets brighter - i hope this won't play havoc with my solar generation or electricity usage meters??

The last "bad" thing is that my electrical tester screwdriver shows that the body of the potentionmeter is live, and so is the heatsink. There are no live wires touching either though!?

[Kev888]

It sounds rather dodgy to me.. sometimes the triac case can be connected to one of the pins (not sure if this one is or isn't), but if so its good practice to insulate it from the heatsink. The cases of POTs can be connected to earth (or occasionally neutral) to help with shielding but normally they would not be live either..

I suspect you may have a dodgy one, or that your repair has caused it somehow, though I'm only speaking generally; maybe someone who has actually bought one can confirm if its normal. Look after yourself - and your solar inverter - this seems at least potentially quite risky

Kev

[themadhippy]

The inverter buzz is most likley swiching noise from the power controller,if its a cheapy it wont have zero point switching,as for the pot being live,not suprised,some early dimmer switches suffered the same proplem,the top pot and mounting nut should be plastic though, its an inline device so theres no neutral or earth so everythings at mains potential although there should be an insulating washer between the triac and heatsink.Finaly electrical test screwdrivers should be destroyed,they give alsorts of spurius indications,use a proper volt meter

[Dr. Dextrin]

The triac in mine has an isolated case (I posted the details earlier in the thread) and my test screwdriver didn't show it or the pot casing to be live. I grounded them anyway, to be safe.

Of course, your device may use a different triac. But the same device also comes in different flavours, with or without an isolated case. There's a link to the datasheet in my earlier post so you can check, if you can read the ID on the triac. However, given the design with the exposed heatsink, I'd be surprised if the case wasn't of the isolated type.

The pot casing being live definitely sounds odd, as it'd be very unusual for that not to be insulated. It's entirely possible your screwdriver is giving a false indication as themadhippy says. But be careful, in case the module is damaged in some way.

The mains buzz from other devices is probably to be expected given the lack of any interference suppression. It's only a problem if it's a problem, I guess. Might be worth checking that your neighbours can still watch their telly, I suppose!

[runthangs]

The inverter and the triac are in completely different locations, but by noise are you referring to electrical rather than audible?

The triac spec:
Triac model: 40A Standard High current Insulated Triac BTA41- 800B
1)IT(RMS): 40A in TOP3
2)IGT: 50A Sensitivity
3)VDRM/VRRM: 800V
4)IDRM: 5uA

photos of the item: http://item.mobileweb.ebay.com/viewitem ... cmd=VIDESC

[themadhippy]

but by noise are you referring to electrical rather than audible?

yep,its most likley doing strange things to the mains waveform that a transformer in the inverter is sensitive too

, I guess. Might be worth checking that your neighbours can still watch their telly, I suppose!

more likley the neighbour 3 doors away

[runthangs]

So after the soldering I housed the pcb in the rear part of a light switch casing, and a plastic transparent CD divider over the pot so the components nor the base of the pot can be touched. Heatsink setup nicely too its a metre long (!) and touches a few pipes for even more heat dissipation, it's all humming along. I put some insulating tape around the pot too to be extra safe. The heatsink isn't during live anymore. It looks ridiculous but does the job for very little money and much satisfaction

J have my laptop switching it via USB based on Bluetooth feeds of pv generation.

I just need a way to read and feed live house consumption to it so I can make switching decisions on that data too.

I figured a digital pot would be my next step but may leave it as is.

[runthangs]

Oh, one thing that's been bugging me, would it have been safer to wire the neutral through the circuit, rather than the live?

[themadhippy]

would it have been safer to wire the neutral through the circuit, rather than the live?

No,in fact its more dangours,with the device switched off someone may expect the rest of the circuit to be dead,grab a live and zap.

[Dr. Dextrin]

J have my laptop switching it via USB based on Bluetooth feeds of pv generation.

I just need a way to read and feed live house consumption to it so I can make switching decisions on that data too.

I figured a digital pot would be my next step but may leave it as is.

I'm puzzled. You have your wort boiling switching on and off according to available electricity, so you stop boiling when the sun goes in, or someone puts a kettle on? Isn't that a bit, err, unconventional? Or have I misunderstood something?

[runthangs]

My controller ive written on LINUX in Perl/c/ bash, and that controller switches power signals via the USB port that switches a Mains plug. I run it on a NetBook sitting in the airing cupboard (will likely port it to a raspberry pi). It reads the live generation via Bluetooth from my pv inverter, and based on thresholds switches the USB voltage accordingly. Also sends emails, has a pause function (as I dont have a simple way to read electricity consumption yet and switch on the deltas). The NetBook runs on a schedule so suspends at set times. The latter two are to compensate for not being able to read live usage.