Refrigerator compressor

[bergfalke4]

Dear fellow vacuum baggers!

I've read alot of threads about using a refrigerator compressor as the basic building block of a vacuum system. I just got hold of a compressor from a refrigerator but I am still unsure about how to wire it. Most threads just seem to assume that you get the pump running and then proceed from there.

I don't have a digital camera so unfortunately I can't take any pictures, but I'll try to explain what I am facing. There's a plastic box on the side of the pump and two cables out of that box. One went to the mains and one to the inside of the refrigator, most probably for temperature feedback.

Am I supposed to do something about the feedback and just connect it the normal way or is it better to open up that plastic box and wire it from there? Is it possible to give a short explanation on how to proceed?

Thanks in advance!
- David

[arneansper]

Hi!

I would suggest you to take a look at the datasheet of some refrigerator compressor. Some companies have very detailed information on the web. Danfoss is a good example. Here is a link to random Danfoss refrigerator compressor datasheet:

http://rc.danfoss.com/TechnicalInfo/literature/manuals/06/PL35F_R134a_220V_50Hz_02-03_Cd41e402.pdf

On the second page you can find the wiring diagram. I will explain it to you:

1) there are accessories that are not needed for you: lamp, ventilator and temperature measurement. You must remove them and the wires that connect them.

2) I added schematics where all unnecessary connections are removed. You must replace the temperature regulator with direct wire (red on schmatics).

3) VERY IMPORTANT: make sure that you connect the case of the compressor to ground (green/yellow wire). Together with residual current breaker it might save your life one day.

If you cannot find exact schematic for your compressor it is still possible to figure out how to connect it. Most of the compressors have two windings: main winding that is powered all the time and start winding that is powered only when the unit starts. There is some kind of device between one end of the main winding and one end of the start winding that passes current only during short time - old units used capacitor, new ones have some other device that looks like a big aspirin pill :) The red dots on the picture are pins that protrude from the case of the compressor - you can see them if you open the plastic box. Determine what two pins have some device between them - those are the ends of the main and startup winding. The other ends of them are connected together inside the compressor and connected to the third pin. In order to protect the unit and to avoid the fire there is temperature cutoff switch that is connected between third pin and live wire (called winding protector on picture).

Connect one wire to the temperature cutoff switch and other wire to other end of the main winding.

So, yes: you must open the plastic box.

I have some pictures of my setup: http://home.cyber.ee/arne/testwing/.

regards,
Arne

[bergfalke4]

Hi Arne!

Thanks a lot for the very detailed description. I'll open the box and see what I can do during the weekend. I must admit that the wiring process looks slightly more complex than I had hoped for, but with patience and some reading most problems are usually solveable. I can only hope that those boxes are semi-generic though, because I don't have a clue about what brand mine is.

If any one else has info or PICTURES on how they wired their compressors, please post. This is an important issue for a lot of us "wanna-be-compositers"! (Well at least for me...)

Regards
- David

[Aerobat152A]

nm :)