Chosing the right power regulator

[lurklaban]

Hi all!

I'm trying to understand and find a effect regulator for one of two heatingelements of 2400W each. Currently we're using a heating fan at 2000W mark power in series with one of the elements which should reduce the effect from 2400 W to around 600W which should give a total of about 3kW. After listening to peopole here, my intent is to raise that power to 3,5-4 kW so I was going for a power regulator but from the eminent book The Compleat Distiller (Nixon, McCaw) I have learned that some regulators/controllers are not appropriate because they generate noise and disturbance/interfearens both in the grid and as RF. Such devices should include phase angle controllers and switches (for example dimmers and motor speed controllers). However, they never tells what type to use but gives a drawing of how to build one (now as I think about it, maby the secret is there...)

Now as I have understood it from reading on the web, the type to use for large resistive loads is a SCR with zero-cross firing (I think that's the same as Burst fire) that does the switching on or off att the zero-crossings of the sine wave and therefore doesn't generate the problems associated with cutting the sine wave. However, I'm not verry sure about if I have understood things right, how important this is and last but not least, how to know from sites like amazon what type of regulator/controller it is I'm looking at.

Any input is greatly appreciated!
Regards
LurkLaban

[lurklaban]

Also, I don't know if the adjustment is linear in voltage, a guess would be that the TRMS voltage is linear in regards to the knob and therefore the power is quadratic, but I donät know if you could trust that or if I have to buy a TRMS voltage meter to know how much power I'm putting out. When used as a motor speed controller I guess these things are not so important since you get quite a good approximation by the sound of the motor, but for heating it's more difficult and trial and error will take some time... Aah, maby I'm making a rooster out of an egg or what ever one says....

[Yummyrum]

You are quite correct in your assumption lurklaban .
Phase controllers are the ones that make a lot of EMI because they switch mid cycle.

Whereas the Burstfire and Time proportional controllers switch at zero crossing point .

You are also quite correct that Phase controllers are extremely non linear in their operation . And the dial is nothing more than a knob . As you also understand , you need a True RMS reading Voltmeter ( and Ammeter) if you want to accurately know the power . Cheap Chinese panel meters will give you a rough estimate but it may be 30-40% out in the mid range .

I’d hazard a guess that 95% of Home distillers use Phase controllers of one sort or another . Yes they do generate a lot if EMI , but while that may have been an issue back when the “complete distiller “ was written and folk listened to AM radio , it is not such an issue in todays digital world where Wireless comms are all up in the VHF and UHF bands where Mains born EMI has a much less severe effect .

Have a look at Auber DSPR1 controllers if you are interested in Burstfire .With these , when you turn it to 75% power , you get 75% if the full power . But also be aware that full power will depend on the exact voltage is at your still house . So a 5500w element at 240v will not be putting out 5500w if your still house voltage is down to 225v .

A key point you made about your motor controller was that you controlled it by listening to the motor .You probably didn’t know the voltage it was getting or the exact RPM it was running at .

The same applies to running a still . Instead of listening ti the motor , you watch the speed of the drips coming out the end . ….or backing it off when the column floods . It is when yiu determine these things that yiu can look at your dials and guages and think “arrh yes thats the point”