Help with a Rotary Phase Converter and an Inverter Welder

By Batfink Date 08-22-2019 14:10

Hi all, I am your average Joe determined to learn how to weld. I was wondering if anybody out there has ever had an issue with running a 3PH inverter MMA welder with a rotary phase converter (RPC)? I have a 13.5 HP/19 Amp 240v single PH to 415v 3PH RPC and a Kemmpi MLS2500 inverter welder. When connected, the welder turns on but it doesn't want to ARC?, The Kemmpi's specs are 3PH, 400v +20%/-15%, 10A with a kVA between 7.7 - 9 kVA.
So far I'm at a loss as to why it's not working?

Regarding troubleshooting so far I have:
1/. Swapped all the phases but no chocolates.
2/. Taken the welder to a mates Factory to confirm the welder is working (which it is! Perfectly!)
3/. measured the volts between phases:
L1 - L3 = 416V
L2 - L3 = 434V
L1 - L2 = 458V

I am thinking of a few possible problems;
a/. Maybe the tolerance between phases are too far apart?
b/. Maybe the welder is having trouble processing the input power signal from the RPC?
c/. Amps??

Anyway, If anyone has had similar experiences, or any switched on members out there have an idea, I'd love to know your thoughts or how you overcame it.

Thanks for reading :eek:

By Jarhead1 (**)

Date 08-22-2019 16:28

Don't understand -
2/. Taken the welder to a mates Factory to confirm the welder is working (which it is! Perfectly!)
If it worked there there and you confirmed should work at home.

Maybe your incoming power is different then where you had it checked out. If so you could of easily blown a board.
Ground issue?

Good Luck

By jwright650 (*****)

Date 08-22-2019 20:00 Edited 08-22-2019 20:06

I think he's concerned about the power from the rotary phase not being clean enough to run the welder. My FIL uses a phase converter to run his milling equipment and lathe his machine shop. I wish I knew more about it to help the OP.

Edit: here is a link to sizing although it appears to have enough voltage.
https://www.northamericaphaseconverters.com/phase-converters/

By Jim Hughes (***)

Date 08-23-2019 12:07

Batfink,
Your L1 looks suspect to me. I know you mention that your RPC is 415v but typically they are 230, 430, and 480v. (Not an expert so forgive me if I'm incorrect) You might ask your friend that you took the machine to, to check his primary voltage on each leg and compare. You mentioned the welder worked fine when you hooked it up at his shop. The term "dirty power" is used a lot in my line of work and it is associated to inconsistent power between legs. Just some suggestions.

By jwright650 (*****)

Date 08-23-2019 16:12

Have you checked each leg to ground? ..rather than the difference between legs?

By 803056

Date 08-24-2019 12:45

Many inverters will operate on single phase, at a slightly reduced output, as well as three phase. Generally, inverters immediately convert the incoming AC to DC. If the incoming voltage isn't correct, it could be messing with other circuitry in the welding machine. It would all depend on the specifics of the machine.

I think we've seen similar issues discussed on this forum, generally from folks overseas where the voltages and cycles (Hz) differ from the country where the power supply was designed and built to operate. As for the phase converter, I have a couple of friends using converters to get three phase. Are you using a solid state converter or a rotary converter? I know a couple of home workshops that use a single phase motor to turn a three phase induction motor. The three phase motor is operated as an alternator to provide three phase power, but the Hz can be off if the rotational speed isn't correct. They use power from the utilities to excite the field, so it is in phase, but the Hz and voltage could be out of kilter if I remember correctly. If I remember correctly, it will operate a three phase motor with a serious drop in efficiency. I could be wrong, its been a while since I've been involved with working with rotary converters. The system may appear to operate without a problem until a load is placed on it.

I'm not suggesting I know what your specific problem is, so I am recommending you have a conversation with an electrician familiar with transformers, power supplies, and solid state electronics might be worthwhile.

Al

By Lawrence (*****)

Date 09-04-2019 16:17

That's actually a big question Dave

Process may or may not be called out in a weld symbol. Process may or may not be called out in contract documents.

Much depends on customer/contract/jurisdictional requirements.

AWS A2.4 covers weld and inspection symbols and this is a good place to start for "standard" weld communication.

If you want to place a process call-out on your weld symbol there is nothing wrong with that.

Typically the code or engineer who is designing the weldment will determine the strength of both the weld and the filler (two different things)

By WeldinFool (**)

Date 09-16-2019 18:22

It looks like "saveisland" has replied to the earlier post that was hijacked by dfick, what a mess. Please start your own threads when posting a question!
As to the inquiry posted by dfick; NO, it is not customary for the welding process to be specified on fabrication drawings. Most engineers that draw these things would probably be wrong anyway.

By saveisland Date 09-15-2019 15:12

I think we've seen similar issues discussed on this forum, generally from folks overseas where the voltages and cycles (Hz) differ from the country where the power supply was designed and built to operate. As for the phase converter, I have a couple of friends using converters to get three phase. Are you using a solid state converter or a rotary converter? I know a couple of home workshops that use a single phase motor to turn a three phase induction motor. The three phase motor is operated as an alternator to provide three phase power, but the Hz can be off if the rotational speed isn't correct. They use power from the utilities to excite the field, so it is in phase, but the Hz and voltage could be out of kilter if I remember correctly. If I remember correctly, it will operate a three phase motor with a serious drop in efficiency. I could be wrong, its been a while since I've been involved with working with rotary converters. The system may appear to operate without a problem until a load is placed on it.