Running a 3 Phase KEMPPI PS2800 Welder on Single Phase

Welding Techniques, Theory, Machines and Questions.

Moderators: Harold_V, Scott

Post Reply
MrCreosote
Posts: 2
Joined: Sat Nov 13, 2021 10:01 am

Running a 3 Phase KEMPPI PS2800 Welder on Single Phase

Post by MrCreosote » Sat Nov 13, 2021 10:22 am

The power cord is wired for 230v single phase.

However the schematic for this welder indicates the 3-phase does not go directly to a 3-phase transformer. Instead it is immediately rectified into a 2-wire supply that goes to the welding power circuitry.

2 3-phase legs are sent to the electronics circuitry. (The power cord is wired to these 2 legs.)

My concerns are
  • powering 2 3-phase legs with 2 leg split phase is going to not produce the "smooth" DC 3-phase legs would
  • smoothing capacitors after the rectification may be over taxed
  • the 2-wire welding circuitry may not function properly due to 180* instead of 120* phase difference

User avatar
BigDumbDinosaur
Posts: 1431
Joined: Tue Jun 28, 2011 9:19 pm
Location: Midwestern United States

Re: Running a 3 Phase KEMPPI PS2800 Welder on Single Phase

Post by BigDumbDinosaur » Sat Nov 13, 2021 10:50 am

MrCreosote wrote:
Sat Nov 13, 2021 10:22 am
The power cord is wired for 230v single phase.

However the schematic for this welder indicates the 3-phase does not go directly to a 3-phase transformer. Instead it is immediately rectified into a 2-wire supply that goes to the welding power circuitry.

2 3-phase legs are sent to the electronics circuitry. (The power cord is wired to these 2 legs.)

My concerns are
  • powering 2 3-phase legs with 2 leg split phase is going to not produce the "smooth" DC 3-phase legs would
  • smoothing capacitors after the rectification may be over taxed
  • the 2-wire welding circuitry may not function properly due to 180* instead of 120* phase difference
First off, can you post some more info about this machine, e.g., make, model, nameplate ratings, etc? Also, it would be very useful to see the schematic.

Meanwhile, I WOULD NOT connect any three-phase welder to a single-phase line. You may end up losing the rectifiers, as well as the filter capacitors, not to mention fill up your shop with vile-smelling smoke. Also, while it should be possible, in theory, to power it from a static phase converter of sufficient size, I'd be leery of trying. Welders are not as forgiving with three-phase power in which one leg is leading or lagging the others, or one leg is lower or higher voltage than the others.
——————————————————————————————————
Research is what I'm doing when I don't know what I'm doing.

MrCreosote
Posts: 2
Joined: Sat Nov 13, 2021 10:01 am

Re: Running a 3 Phase KEMPPI PS2800 Welder on Single Phase

Post by MrCreosote » Sat Nov 13, 2021 1:29 pm

It is a KEMPPI PS 2800 / 4J 6142254

The spec plate on back is all symbolic.
I have no idea what F1, F2, U0, U1, U2, I1, I2 and S1 mean

https://imgur.com/jtN1KHV spec plate on back
https://imgur.com/O4bBkDy schematic zoom of 3-phase input rectification
https://imgur.com/Dj8qHSA schematic full

The following is technically off topic. There is a "mysterious 6-pin connector" on the back panel that is not shown in the user manual. Because of the circled V and A beside it, I'm speculating it is a control for constant voltage or current since this box can also be used for MIG. The following images show the connector and have a schematic zoom to the only 6-pin connector I can find.

https://imgur.com/AGYCzXX schematic zoom of mysterious 6-pin "V - A" connector
https://imgur.com/FvYsyhM Mysterious 6-pin "V-A" connector on rear panel not mentioned or shown in user manual

NOTE: There was a post from a fellow who supposedly ran a PS 2800 on single phase the trick being to connect the 2 legs that powered the electronics. The fact that this unit does not have a 3-phase power transformer at the power input suggests it may be "single phase friendly?"

Post Reply