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Discuss Industrial Dough Mixer (Kemper SP125) in the Commercial Electrical Advice area at

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I am a baker and an apple juice producer.
I built my own apple juice pasteurising factory and associated electrical controls, I maintain my own equipment and have my work checked by our electrician before allowing any employees to touch it! I am reasonably competent but I am not an electrician.

I am having fun bringing by Kemper SP100 commercial dough mixer back into use, previous engineers over the decades have f'd it right up and I am getting it back to factory spec.

I am building a diagram of how it is wired now and I have a diagram of how it should be wired. My factory wiring diagram, I have translated as well as I can from German and I have identified most of the components in the diagram. There are two extra contactors which I cannot identify in the second/third picture. The 5th picture is a Star/Delta arrangement to allow fast and slow speed on the spiral arm. 1c1 (left-most contactor in photo 2/3) is the contactor for the bowl rotation motor. The middle and right contactors in this photo may be 1c2 or d2 on the circuit diagram (the label was loose in the bottom for 1c2 so could have come off either). I think the right most might be d2 based on the terminal numbers BUT, why is the extra contactor not mentioned in the diagram, there is no mention of 1c2 anywhere?

I wondered if anyone was familiar with these machines or had any ideas?
I hope you can see the pictures and the diagram ok but please let me know if not.

Any help greatly appreciated.
Thanks in advance,


  • kemper wiring annotated.pdf
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Not familiar with the mechanical design of the specific machines in your factory, but what have you done in terms of a risk assessment for the operation of your machines? If there is an accident and you can't provide satisfactory evidence of your risk assessment process which guided your design then the HSE will prosecute under PUWER.

Having a nice panel, and restoring the machine to however it used to be won't be sufficient.

Are there any possibilities of trapping, entanglement, burning, scalding, chemical hazards from cleaning processes?

Edit. Had a look at your pdf circuit diagram. There's a something labelled as a guard switch. So the original designer has identified a hazard. Your works mean you are now responsible so you need to meet the requirements of Machinery Directive, and more importantly, PUWER. Both of which are legal requirements and are far more important than what contactor might do what.
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Staff member
Looking at connector block city directly above it and the different type of wire used it appears 1c2 was added later. You'd need to trace the wiring to figure out what its purpose might have been.

My advice would be to check all the ancillary components are to spec such as control buttons, e-stop, lamps, motors, limit switches etc then rip out the wiring and start again by wiring it back to manufacturers spec.

If it's just you using the machine at home or in your garage it's one thing but as pointed out above if the machine is used by employees in a commercial application and you deviate from the original design or wiring spec then you're personally legally responsible if anyone is injured or killed.

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