My Power Controller

[Icefever]

To top it off, my brew shed was too big to move, and the guy who bought my old house has chopped half of it up, painted it some gay colour and turned it into a summer house :-(

Oh the pain of it all dear boy....

[Anavrin]

Nice bit of kit, I never got round to adding any type of display to mine, although I should, even if just something temporary so I can judge it in the future.

Sounds like your T500 is a little more powerful than advertised. 8.5amps at 240volt
Is a little over 2KW but that doesn't surprise me, there can be big tolerances in resistive heating elements, I suspect the resistance of the element will increase as it gets older with use, taking more current as it ages.

[Almanac]

..... and the guy who bought my old house has chopped half of it up, painted it some gay colour and turned it into a summer house :-(

which ones are the gay colours



AM

[Anavrin]

A light pastely blue/grey

I loved that shed, it even had blacked out windows

[Easydrinker]

I am loving,and sympathising with the tale of the shed.
There are Heathen out there.
Take care.
Robert.

[ant]

Hmm. You are confusing peak voltage with output voltage. The peak is not 240v but over 300v. Output voltage is RMS, root, mean, square. This is just a more precise way of defining that the output voltage is the average of the whole area under the sine wave; not the voltage of the peak. That is why we get 240v from a sinewave with a much higher peak voltage. Please belive me when I tell you that the output voltage drops the moment you clip anything from the sine wave. Not only after you clip past the peak. Put a voltmeter on yours and you will see the truth of what I am saying with your own eyes. There is no way to use a phase angle controller to get half power at 240v. It just doesn't work that way. However your exploration of possible ways to do things within your current understanding of how things work was excellent. As you hone your understanding your analytical, creative mind and innovative perspective will continue to serve you well.

Aidan: i am pretty sure your power controller is just fine. You have used it safely until now and nothing we write changes that.

Fil: looking good.

[Easydrinker]

I find it kind of freaky what people with real knowledge/insight know.
My power controller is simple and works,it turns down the power supplied to the heating element,slows down the boiler,and doesn't get too hot.
It's even got a green and yellow stripey wire,so that must be good?
That last was a joke....
Really,respect to the electro-heads out there,but when I finally understand what you are saying here,it will be increased.
Robert.

[ant]

In a very real sense that picture of a power controller is straight to the point of why we use them here. It is all you really need to know when you have one. Visualising the fine detail of how they do what they do is something we only do becuase it pleases us. It is interesting to know how the universe works and consider the possibilities that offers us, as Anavrin was doing. There is allways more to learn for those who enjoy learning. It can be a pleasure in it's own right.

[Anavrin]

Hi Ant

You got me thinking and questioning myself now, it's been 15 years since I got my HNC in Electrical/Elecronic Engineering, I seldom need my almost forgotten power electronics knowledge!

I'll have to do some experiments I think, if only to clear the argument in my own mind! Lol, shame I no longer have an occiloscope to hand :-(

I'll let you know my findings, in any case as I strive for the perfect neutral, I wouldn't want to fall out with someone who has something I find far more interesting, like in your SPP machine :-)

[ant]

Don't worry, no falling out at my end. I don't mind being wrong because it means learning. I accept the 24-380v PAC will work for us. Might not turn down to zero in worst case scenario. I'll use a 240v PAC just on principle.

I wrote a long explanation of RMS and how our education systems only ever teach us approximations without even telling us they are approximations. It had calculus and everything. Board lost it when it asked me to log in again. Oh well. Just use a voltmeter you don't need an oscilloscope for this. Measure volts out and watch it drop as you dim.

Keg won't work on induction. Could modify it but would mean molten aluminium to fill the void between the curved base and a flat steel plate. Not keen on that.

Back to the cutter to try and get it reliable. Or replace it.

[Anavrin]

Your right Ant, I was confusing Peak and RMS, the peak voltage will stay the same until you clip past half way and the effective voltage (RMS) will reduce from the start of the waveform clipping.

I borrowed an oscilloscope of a colleague, not used it yet but I'm going to use it to take some screen shots of the waveform, along with some readings from my multimeter to show how the power controller work using my setup, if anyone's interested.

[Anavrin]

Hi Guys

I've put this together for anyone wanting to visualise how an AC phase angle controller clips the AC sine wave and in turn lowers the power to the heating element in your boiler.

I borrowed a scope and connected it across the power input on my boiler, also connected is a volt meter so you can see the voltage as the dial is adjusted from max to min.

Here's the setup, it's my boiler still filled with backwash from last nights stripping run.








Next is a series of pics as I turn the power down from max to min, the AC waveform can be seen on the screen of the scope and to the left of the scope you can read the voltage on my multimeter.



















This last pic shows the resistance of my heating element, just thought I'd have a look while the meter was connected.



And there you have it, it's what's really going on in your box :-)

[Easydrinker]

A picture is worth a thousand words,thanks for taking the time,I think I have a better understanding.
Knowing how stuff works is indeed a step up from knowing that it does.
Robert.

[ant]

What is the lowest voltage you use in practice? The reason I ask is that panel mounted volt/amp/wattmeters are less than a tenner now and could be an alternative to a straight volts, amp meter. It seems though that both the dual volt/amp meters and the watt meters have a lower range cut off of around 80v. I have no idea what happens if you drop below 80v, maybe just stops working. Is this low enough or should I carry on searching?

[Easydrinker]

I don't think that I've ever gone below 850V.
Not even out of curiosity.
Away from home for a couple of weeks,but have about 18 litres of strip waiting for my return,will have to dial it down to zero and see what happens.
Robert.

OK,I really did mean 850 W !
A drop too much before posting methinks.