Contactorless CP-300 H-K Conversion

I have recently been working through a Miller CP-300 conversion with the help of Dave Kamp. I will add pictures of my conversion, and I am sure Dave will be along at some point to add the modified schematic showing the connections.


Travis

A few before shots of my machine once I got the covers pulled off and discovered that I didn't have a contactor like the manual said I should. A quick check of the right side cover and luckily I had a schematic glued on the inside of the cover that seemed to match how the machine was wired. A quick email to Dave, worried that I had a machine that couldn't be converted, was quickly responded to with a "I think we can make that work" answer. I took a full frontal shot of the wiring diagram and sent it over to Dave so he could modify it for a before and after to show the connections that needed to be changed. In the mean time he suggested I check out another thread here on PM where Erik converted a cp200 that didn't have a contactor. I started following the directions outlined in that thread and got everything rewired and threw the switch. The machine "hummed" pretty loud, like the transformer was loaded pretty heavy. I shut it down and went inside to email Dave, who had responded saying hold off as it looked like we could convert my machine without having to change the secondary side at all. I proceeded to undo the secondary side of the conversion and return it back to stock. In the mean time Dave sent over the modified schematics. I was unable to complete the conversion before leaving town for the 4th for a long weekend. I have since finished the conversion following the schematic Dave has created. My machine has 208, 230, and 460 jumper settings. We are using the 208 windings wired in series, feeding them with a 240 input, which puts us within nominal voltage input ranges for the windings. Once sorted this is a very simple conversion as all of the work can be completed on one side of the machine with a screwdriver and socket set.

I've been working with Travis on this one between business trips... both his and mine, apparently... but stand by. Ken Simola had good success with his 300's, so I'm sure this one will as well.

I know this is an old thread but, I’ve come across a cp-302 in good shape for cheap. I’ve been doing some investigating and was going to try and use the cp-300 conversion on it then I noticed this machine doesn’t use a contactor. Can this still be done another way? Thanks for any help.

I replied to your other thread. Travis's machine (for which this thread was made) is likely similar to yours... I believe, however, that Travis's machine is a 208-230-460 machine, which means it has the original CP-200's delta wiring, but has additional taps for 208v... and if I recall correctly, it was simply a matter of employing the 208v taps, and the turns ration from primary to secondary came out perfect... no need to change the output to wye.