Power Controller

edited January 11 in General

I am busy putting the finishing design touches on a 3,000L still and am now starting to look at the power controller.

The still is 54KW, 3 phase, 380VAC. There are 6 x 9KW heating elements. The still will be 100% automated where heating output control is 4-20mA to the power controller.

I received my first quote yesterday and the price was scary. It was for a Thyristor control unit.

The quote today was for a fan cooled WATLOW unit model DC32-40S0-0000 and the price was quite reasonable. Now I know WATLOW to be a quality item.

But it got me thinking, ...... what are others using where they accurately control power to the heating elements.

Cheers from sunny SA. Today about 33 deg C.


  • edited January 12

    I’d say use contactors for 4 of the 5, and just make 1 variable, but contactors are expensive too.

    From a panel perspective, you can just use a 4 position switch for the power, and one rotary knob for the fine control. PLC even easier. Bonus is you can get away with a much smaller variable controller.

  • Thanks @grim . The concept of how I do things is that no element power is at 100% whilst others are say at a lower value. They must all be identical at any one time, hence the fancy controller. The logic behind this is prevention of element burn on. As it is, each of the six 9KW element is at a fantastic value of 4.6 watts/cm2

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