What's new
What's new

Haas-Kamp on Dimension 452

erikg

Plastic
Joined
May 30, 2013
Location
Minnesota
Hello again, all;

My Hobart RC301 is still running strong after being converted... I even bought a new Miller R-115 wire feeder for it (the drive rolls for the L-Tec feeder are really hard to find/expensive).

I've acquired another welder I'm considering using for Tig and Stick... a Miller Dimension 452. This is another three phase welder that's a little newer design than most of the Miller welders I've seen converted here and elsewhere. It's a multiprocess box with both CC and CV modes, to make things more complicated. Controls are a digital/analog mix, but it runs on the same basic transformer and rectifier circuit that most other converted welders use.

I have two questions that I'm hoping someone here can help me with.

1) Has anyone converted this welder or a similar model using the Haas-Kamp method?

2) How can I estimate how many capacitors will be needed to convert a 452 amp (600 peak) unit? I'd like to use stud mount caps, which I don't have on hand and will have to order, hence my desire to estimate.

I've got a couple months before I start this most likely, both because I've got other projects going and because I'll need the ground to thaw before I can run a new feeder cable to my garage to power this sucker.


Thanks,
Erik
 
Hi Erik!

Glad to hear the RC301's working out well... don't remember when the last update to your RC thread was, and I'll confess, I haven't really had time to go peruse the postings much lately.

The original CP-200 thread had the basic formula that we STARTED with... and this got us somewhere in the ballpark.

It isn't the machine's output that really determines what you need... it's more the INPUT CURRENT and VOLTAGE that determines the capacitor value.

Let's start by getting the voltage issue out of the way. If you're feeding the transformer windings with 240v, it's not unlikely that you'll see upwards of 430v appear across the capacitors when conditions are just-so. That's because the transformer primary on the B-phase will be 'reflecting back' under certain conditions, and it is possible that it could be as much as 180 degrees out-of-phase with the input. Mathematically, that suggests that a 240v input could result in a 480v peak across the capacitor. In real life, the only time you'd see 180 degrees, is if a very serious error was made in capacitor value. We're really shooting for 90 degrees at max... so a 430v cap (a fairly standard voltage) will be sufficient in most cases. Remember- these are oil-filled 'motor run' caps... they're extremely robust, and built for this kind of duty.

So to the value...

What I've found, is that the capacitor value to 'wake it up' isn't particularly precise. The formula you see in the original posting is based on the concept that a circuit consisting of a capacitor and an inductor, when operating at a fixed frequency, will result in a certain amount of 'phase shift'. It gave us a clue of 'about how much' would actually be likely to 'start' the process of the center coil circulating A and C's flux.

So let's say your Dimension 450 has an input power range of 240v on each leg... it'd be around 8.5kw, or around 20A per leg. When done, you'll be carrying about 35A on each leg of your single-phase system. To get appropriate phase shift, I'm gonna estimate somewhere around 120uf on each lead... that's about where the Miller SRH-333 was happy.
 
Dave -

Thanks a bunch!

From Miller's doc here: http://www.millerwelds.com/pdf/spec_sheets/DC19-2.pdf

I see that the Dimension 452 with 230 volt three phase input will use up to 90 amps in CV mode and 75 in CC. Per the same doc, it's a 22 kw box. So from the original thread: I = 2 * π * F * C * V

Rearranged, with values subbed in:

C = (90 / 3) / 2 * 3.1415 * 60 * 230

C = 15 / 90477.87 F

= 0.0001657 F

...or about 166uF.

Actual voltage will end up being 245 at my shop. So, I'm thinking of starting a bit lower, with about 2 60s and a 30 on each end of the B phase, and I'll play around from there.

Sound reasonable?

No doubt I'll have some surprises with the controls and I'll have to rewire the input contactor to make sure it really turns off, but that's where all the fun is.

Erik

PS: I think this is the largest welder I'm going to try to convert. After this I'll have to go to generator/welders :)
 
166 would certainly be in the range I'd expect for that power level.

For what it's worth, the ballpark figure doesn't take into account the nature of the transformer's core density/permeability, etc... it's based totally on the fact that we know frequency, current, and voltage, and of course, we ASSUME that the dern'd thing worked when it left the factory.

This is because... that although one could measure and calculate for variations in core permeability, the reactance VARIES based on load, so it's a moving target, AND... all we need, is to get close enough to the ballpark to hear the crack of the bat, and cheer of the crowd, to know that there's a game on.
 
Help!

Dave,

Do you by chance have a diagram for this? I have the same machine and would like to convert to single phase myself. Also how many amps can I expect to draw total when welding?

Thanks!

Hi Erik!

Glad to hear the RC301's working out well... don't remember when the last update to your RC thread was, and I'll confess, I haven't really had time to go peruse the postings much lately.

The original CP-200 thread had the basic formula that we STARTED with... and this got us somewhere in the ballpark.

It isn't the machine's output that really determines what you need... it's more the INPUT CURRENT and VOLTAGE that determines the capacitor value.

Let's start by getting the voltage issue out of the way. If you're feeding the transformer windings with 240v, it's not unlikely that you'll see upwards of 430v appear across the capacitors when conditions are just-so. That's because the transformer primary on the B-phase will be 'reflecting back' under certain conditions, and it is possible that it could be as much as 180 degrees out-of-phase with the input. Mathematically, that suggests that a 240v input could result in a 480v peak across the capacitor. In real life, the only time you'd see 180 degrees, is if a very serious error was made in capacitor value. We're really shooting for 90 degrees at max... so a 430v cap (a fairly standard voltage) will be sufficient in most cases. Remember- these are oil-filled 'motor run' caps... they're extremely robust, and built for this kind of duty.

So to the value...

What I've found, is that the capacitor value to 'wake it up' isn't particularly precise. The formula you see in the original posting is based on the concept that a circuit consisting of a capacitor and an inductor, when operating at a fixed frequency, will result in a certain amount of 'phase shift'. It gave us a clue of 'about how much' would actually be likely to 'start' the process of the center coil circulating A and C's flux.

So let's say your Dimension 450 has an input power range of 240v on each leg... it'd be around 8.5kw, or around 20A per leg. When done, you'll be carrying about 35A on each leg of your single-phase system. To get appropriate phase shift, I'm gonna estimate somewhere around 120uf on each lead... that's about where the Miller SRH-333 was happy.
 
Dave,

Do you by chance have a diagram for this? I have the same machine and would like to convert to single phase myself. Also how many amps can I expect to draw total when welding?

Thanks!

Hi TJ-

Sorry, Eric did it, using my diagrams of the CP-200 and SRH-333 as the 'template', and the formula included to get a WAG of the capacitor value.

From the start, i've helped people do this conversion with the request that when they apply it to OTHER machines, they document and post what they did such that others can follow THEIRS just as they'd followed MINE. In SOME cases, this does happen, but in many, it seems that once they get it going, their interest moves to using it, and the documentation mysteriously ceases... and the result is, I have people begging me for assistance on the same machine over and over.

Perhaps Eric will see this and jump in, but having been absent since 2018, I suspect it's a case where he accomplished his mission and moved on.
 
Hi TJ-

Sorry, Eric did it, using my diagrams of the CP-200 and SRH-333 as the 'template', and the formula included to get a WAG of the capacitor value.

From the start, i've helped people do this conversion with the request that when they apply it to OTHER machines, they document and post what they did such that others can follow THEIRS just as they'd followed MINE. In SOME cases, this does happen, but in many, it seems that once they get it going, their interest moves to using it, and the documentation mysteriously ceases... and the result is, I have people begging me for assistance on the same machine over and over.

Perhaps Eric will see this and jump in, but having been absent since 2018, I suspect it's a case where he accomplished his mission and moved on.

Understood sir I also completely understand how that works. I appreciate your response sir and the assistance. I am hoping to be able to figure this out soon! Thank you again for the reply!
 








 
Back
Top