PHOTOS of my 17.5 HP phase converter

The die that I have says that it is for #6.

I hope that it works, we'll see. I bought some #6 ring terminals, I hope that they fit the crimper.

DoN, do you think that there is value of soldering after a proper crimp (that does not pull out despite string tugging)?

i

O.K. And it should have a red dot on each half. Perhaps a

1/10th inch shallow drill hole filled with the paint. (The blue version is so dark that it is sometimes hard to see.)

Most of them will, though the ones by AMP are the best, of course.

*No*! If it pulls out, it was not crimped hard enough, or was the wrong size of wire for the terminal and dies.

One major threat if you flow solder into it is that it will wick on through and into the insulation a little bit, turning your multi-strand flexible wire into a solid wire -- much more likely to fail during vibration.

For soldered connections in aerospace applications, where vibration is a given, there are anti-wicking tweezers to prevent this from happening while you solder the wire to a terminal.

Enjoy, DoN.

I am not so sure of the red dot. Will check. Also, I bought UN-insulated terminals.

Mine is by AMP, accidentally.

Aha. Since vibration is an issue, I will avoid soldering, but will try to make sure that my crimps are strong.

i

DoN, sorry, forgot to say Thank You.

i

According to Ignoramus20852 :

You're welcome, DoN.

Hi,

I am going to make a phase converter similar to the two stage unit you have. One thing I have been unable to get a definitive answer on is sizing the ider starter (mag). So... running a 10HP ider off single phase, do you size the starter the same as if you were suppling it with 3 phase, or do you have to up size it as if you were suppling a 10HP single phase.

Your set up is similar in that I what to start a 10HP idler with a size 2 starter (rated 15HP @ 230/3P or 7.5HP @ 230/1P)

Any clear opinions on whether the size 2 is fine or undersized????

Hi Glen,

You should size the starter for single phase as you have single phase entering the convertor. Presumably you have a starter with three sets of contacts, and you use two sets for single phase operation or three sets for three phase operation?

The rating of the starter will be based on the current which the contacts can handle. For a single phase motor the equation giving the power in terms of line voltage V and line current I is:

P = I * V

For a three phase motor it is:

P = 1.732 * I * V

Given that I and V are the same in this case, one would expect the three phase power rating to be 15/1.732 = 8.6 hp. The manufacturer has obviously chosen a 7.5 hp, which is a nice round number. What machines do you plan to run from your convertor? Technically you should probably go for a larger starter, but if you're only going to run your convertor lightly loaded and don't insist on doing everything by the book, you'll probably get away with it. But if I was building the convertor myself I would go for a larger starter.

Best wishes,

Chris

Correction: one would expect the single phase power rating to be 8.6 hp.

Good question.

I figure that if a starter is good for 15 HP three phase, it should be good enough to run a 10 HP motor from single phase, when the motor is not loaded and is only using the single phase to make the third phase.

Note though that the answer also depends on the load that is applied to the phase converter, and whether load current for L1 and L2 would go through the starter or not.

I am actually finishing up the phase converter and I am making sure that the load current for L1 and L2 does not go through the starter. Besides the starter, I also added an output contactor that would turn on L1 and L2 directly from mains, and L3 from the idlers.

The idea, again, is to avoid L1 and L2 current from going through the mag starter, at the same time without ever having output L1 and L2 energized without L3.

Please note that this is my uneducated opinion, I built something that seemingly works, but I am not an authority on electricity.

i

I agree with your post, but I want to note that size 3 starters are very expensive, even used.

i

In this case Glen should probably make his choice based on what he intends to run from the convertor. The size 2 should be fine for a 3 hp Bridgeport (say) but could be inadequate for a bad ass welder like yours :-).

By the way, I like your pics of the new phase convertor. I missed the pictures when you first posted them, but just saw them now. Nice job.

Chris

I am not so sure. If a load is turned off when the phase converter starts, then all the contacts of motor starters would already be engaged by the time my welder is turned off. And they can conduct quite a bit more than my welder would require.

Again, my motor starters are wired to only supply L1 and L2 to the idlers. They are not supplying current for the phase converter load. That reduces the current that would go through the mag starters.

Thank you. It is not yet 100% done. I did a few things today to improve safety (according to suggestions that I received), and wired a push botton switch for the second idler.

It is quite amazing, in fact, to notice the great reduction in noise and vibration when the second idler (and, more importantly, a second set of caps for another leg that makes all my caps balancing), is turned on.

i

Hi,

The largest load will be a 10HP (+ 1HP feed motor) wide belt sander. It will have a heavy starting load due to the inerta of the steel rolls. I will also want to run a 3HP dust collector at the same time. The smallest load will be 1.5HP. So everything from 1.5 to 14HP at one time.

For idlers I have a 15HP, a 10Hp, a 7.5, and a 5HPavailable. I believe (hoping!!) that I can get away with 15HP of idler. Have max of 60amp 240 single phase supply but I am going to try with 50amp first (much less work).

Haven't decided whether a single 15HP would be the way to go or a 10/5 combo. (more complicated).

Thanks, Glen

In that case I would look for a larger starter.

My guess is that you'll probably get away with a 15 hp idler if your convertor is well balanced. Don't take this as fact, though: ask Jerry Martes or Bob Swinney. They seem to be the phase convertor experts in this group.

Of course you can also build a prototype phase convertor quickly, check that it does what you want, and then build a housing for it.

Best wishes,

Chris

You need to work on general wire routing and workmanship issues, in addition to some of the other items pointed out in this thread. In general, wires and cables are not routed as the crow flies, they should go in straight lines, get bent at the proper radius for the diameter and change direction 90 degrees. Wires running into breakers or terminals should enter/exit in a straight line. Adequate wire length should be available for changing out devices in the future. Some electricians can line up all of the wires in a panel with the precision of the Rockettes, I'm not sure that's necessary, but some evidence of symmetry and a plan does make future service easier and you will feel good about the final product.

Note that the equipment would, hopefully, be started after the phase converter is fully running. So I am not sure how a large load changes the equation for the idlers starter all that much.

That would be the way to go.

i

I have been making changes today and they were in this direction. I agree with you.

i

Tell me the size of the caps in uF and the voltage you measure across them and I'll come up with some values for you.

240 VAC, each cap is 94 uF. i