Wiring up a 30HP rotary phase converter

[Willie B]

Correct re the three sets of four for 230VAC.

Typically you would bolt all of the lugs together, wrap with a single layer of high grade electrical tape (Scott 33 or 88), then wrap about 5/16" thick with rubber splicing tape (3M Temflex or equivalent), and then finish off with electrical tape on the outside.

The reason for the electrical tape first is because the rubber splicing tape can be quite sticky, and if you ever have to take the connection apart it can be a real pain to remove the sticky splicing tape from the connectors. With a first layer of 88, you can cut through all of the tape with a knife and peel it back from the connection, and save yourself several minutes of clean up time.

In addition to bolted lugs, the other standard way of joining the wires is using a split bolt, taped up similar to what I wrote above. In your instance I would personally use the existing lugs and bolt them.

While I use Temflex 1700, I urge you to consider the rubber splicing tape as a filler. You want enough 3M 33+ to do the job. Split bolts, especially if you get too large have a lot of knobby points that compress the rubber splicing tape. It is common for it to chafe through. I've also seen the rubber stuff split wide open when it gets old. It sometimes makes a wild fireworks show.

In this application I'd leave the Temflex 1700 in the drawer, and use 33+ with Scotchfill, then another heavy layer of 33+. My father then used friction tape, a heavy tarry cloth tape.

The conductors you are working with aren't very stiff, but trough work where heavy conductors (500 MCM) are tapped you need all the protection you can get.

[scsmith42]

While I use Temflex 1700, I urge you to consider the rubber splicing tape as a filler. You want enough 3M 33+ to do the job. Split bolts, especially if you get too large have a lot of knobby points that compress the rubber splicing tape. It is common for it to chafe through. I've also seen the rubber stuff split wide open when it gets old. It sometimes makes a wild fireworks show.

In this application I'd leave the Temflex 1700 in the drawer, and use 33+ with Scotchfill, then another heavy layer of 33+. My father then used friction tape, a heavy tarry cloth tape.

The conductors you are working with aren't very stiff, but trough work where heavy conductors (500 MCM) are tapped you need all the protection you can get.

Oscar, WillieB is the professional electrician. Follow his advice instead of mine.

Willie, thanks for chiming in. I had forgotten the name of Scotchfill - thanks for the reminder. My thought with the Temflex was to wrap it multiple times until a thickness of at least 5/16” had been obtained, thus using it as a filler. Your way is better though.

In what instances should one use 33+, and in what other instances is 88 a better choice?

Thx.

Scott

[Oscar]

I have 33+, and I have lots of Scotchrap. Any reason why Scotchrap wouldn't work in the place of Scotchfill?

[scsmith42]

Scotchfill is a putty like substance that you can mold around the bolt and terminals. It allows you to put a good, thick insulating cover in place around the sharp edges on the fasteners.

Scotch wrap is a somewhat thin tape. Yes, you could use it but you’d have to wrap a lot of it around the lugs in order to have an adequately thick insulation.

[danielplace]

Daniel, according to the tag on his RPC (shown in post #43), the FLA is 71 at 230VAC. Wouldn't he need to run #4 from his RPC panel to the idler, instead of #8? Even with 90 degree C insulation, a #8 is only rated at 55A.

You only need those amps on the single phase feeding the converter panel.

Rotary phase converters are typical. Here are some wire size charts for similar units. Check the 30 hp line. His could be wired with similar sizes I believe and work as designed.

Not any phase converter guru. Wired several over the years in smaller wood working shops.

It does seem odd that the idler wouldn't need at least the same as the C phase it is feeding out to your 3 phase on.
That is how they are designed and work though. I think the two single phases are actually bucking to the created phase so they cancel each other out and only the unbalanced returns on the C phase to the idler. For this reason the idler wiring can be smaller. I wouldn't take it to the bank that is how it is exactly but of course that leg doesn't have same voltage as others to ground so it is not taking the load of the others either maybe.

He should have some similar specifications from the manufacturer of his exact unit.

[Oscar]

According to the instructions from the motor manufacturer, there is actually another possibility for the motor wiring. The one inside of the plate I removed to reveal the wires is the low-delta, but there is also a low (voltage?)-Wye:



Does this change anything? I have not familiarized myself with the differences between the delta/wye wiring schemes.

[scsmith42]

Rotary phase converters are typical. Here are some wire size charts for similar units. Check the 30 hp line. His could be wired with similar sizes I believe and work as designed.

That’s good info to know - thanks for sharing.

[danielplace]

According to the instructions from the motor manufacturer, there is actually another possibility for the motor wiring. The one inside of the plate I removed to reveal the wires is the low-delta, but there is also a low (voltage?)-Wye:

Does this change anything? I have not familiarized myself with the differences between the delta/wye wiring schemes.

Oscar,
I believe it would wire to the Delta scheme but don't wanna say anything is 100% fact and steer you wrong. All your questions on your unit that aren't spelled out clear and making sense then I would call the tech line and tell them what you have a question with and be sure they know your intended load is a inverter welder. Too much money at stake in the converter and your welder to guess on anything your not sure of.

The tape insulation you want rubber 1st, friction next and electrical over that. Get single lugs for your lines to bolt up to your motor leads. A crimp type would be neater but a small set screw type #6 lug isn't huge and would tape up nicely. Probably want to cut any length of extra bolt off.

[ferrret3238]

I would wire that motor up delta for simplicity. There's really no benefit to making it wye unless you're getting into wye start delta run motor controls. Some of the larger lathes and compressors are wye start delta run motors. As far as taping, usually I go with varnished cambric for the first layer, then rubber mastic, then the scotch 33+. For that I would just bolt them and wrap a few layers of 33+ upside down on the splice, then rubber mastic, and then a layer of 33+ again. Most people don't know what varnished cambric is any more. I can't tell you how many times I've been pissed at somebody for directly wrapping the bolt/split bolt with rubber mastic.

[Oscar]

I have emailed the vendor regarding the motor wiring (low-delta scheme), as well as input power→panel and panel→motor wiring to have definitive answers.

[Oscar]

No dice, but I'm pretty sure I have my answers anyways. I've decided on what wire I'm going to use, but I'm not going to disclose it because I don't want danielplace/willieb to faint and lose consciousness, lol.

[Willie B]

No dice, but I'm pretty sure I have my answers anyways. I've decided on what wire I'm going to use, but I'm not going to disclose it because I don't want danielplace/willieb to faint and lose consciousness, lol.

Your installation, not mine. I offer advice. It's absolutely your decision.

[danielplace]

No dice, but I'm pretty sure I have my answers anyways. I've decided on what wire I'm going to use, but I'm not going to disclose it because I don't want danielplace/willieb to faint and lose consciousness, lol.

Your installation, not mine. I offer advice. It's absolutely your decision.

Willie,
I think he just said he is going to use as many #10's as it takes. Lol.

4 runs for the single phase input, 2 runs for the idler and 3 runs to the panel and 3 runs for the welder unless that gets hardwired right to the breaker. All the same color. OMG !!! Phase tape baby.

Don't forget to take a single one at least maybe two for the ground. Get some green at least.

Guessing your not installing over current feeding the panel itself. You bought a main lug only 3 phase panel ?

[Oscar]

Yes, there will be OC on the 1-Φ side from the garage sub-panel. I'm thinking 100A will suffice. I'm also going to use a BR125 2-pole breaker as a disconnect right before the RPC panel. The 3-Φ Eaton main lug will be installed between the RPC panel's T1-T2-T3 terminals and the load.

[danielplace]

Yes, there will be OC on the 1-Φ side from the garage sub-panel. I'm thinking 100A will suffice. I'm also going to use a BR125 2-pole breaker as a disconnect right before the RPC panel. The 3-Φ Eaton main lug will be installed between the RPC panel's T1-T2-T3 terminals and the load.

Yes yes. Brain dead !! the BR2100 breaker in subpanel is feeding the RPC..

That is no panel. Single breaker enclosure. That is just a disconnect. Room for 1 breaker.

For about the same money you could have bought a panel. Then when you add things all you need to do is plug in the breaker.

This is what I think you should have bought well of course IMO. Just save a lot of time later. Not a big deal. Use that and when you add something you chuck it and get a panel.

https://www.homedepot.com/p/Eaton-12...125R/202276717

24 spaces.
Good for 4 breakers in your setup.

[scsmith42]

1/0 and 100A breaker should work just fine. I ran a 30hp RPC on a similar sized breaker for years.

Ditto Daniel's advice for using a panel instead of a single breaker enclosure. With a panel you have the ability to easily add additional 3 phase equipment. Frequently you can find a better deal on 3 phase equipment as opposed to single phase because fewer people have the power to use it.

[Oscar]

Yes yes. Brain dead !! the BR2100 breaker in subpanel is feeding the RPC..

That is no panel. Single breaker enclosure. That is just a disconnect. Room for 1 breaker.

For about the same money you could have bought a panel. Then when you add things all you need to do is plug in the breaker.

This is what I think you should have bought well of course IMO. Just save a lot of time later. Not a big deal. Use that and when you add something you chuck it and get a panel.

Correct, not a panel to distribute to various 3-Φ machines, just to use as a disconnect. That only cost me $30, so it's not quite "the same amount of money".

But you do have a good point. I can always return it. I may consider that 3-Φ panel you linked. I don't think I'll be getting any other 3-Φ machines until next year. For right now it's just the welder, that's why I bought that single disconnect.

[danielplace]

Correct, not a panel to distribute to various 3-Φ machines, just to use as a disconnect. That only cost me $30, so it's not quite "the same amount of money".

But you do have a good point. I can always return it. I may consider that 3-Φ panel you linked. I don't think I'll be getting any other 3-Φ machines until next year. For right now it's just the welder, that's why I bought that single disconnect.

Yes $30 not a big deal. Wasn't sure what you paid. Sometimes those singles cost almost as much as small panels from some manufacturers. Would nice to have the cover over the breaker handles also for little more protection from in shop abuse.

I am jealous actually as I have passed on 3 phase equipment for lack of a way to power it. Shop is full but nice 3 phase lathe or mill would be nice.

They have a 3 phase motor option for my lathe that runs on single phase. Gives you awesome motor speed and reverse control too. Variable frequency/speed drive setup.

[Willie B]

Willie,
I think he just said he is going to use as many #10's as it takes. Lol.

4 runs for the single phase input, 2 runs for the idler and 3 runs to the panel and 3 runs for the welder unless that gets hardwired right to the breaker. All the same color. OMG !!! Phase tape baby.

Don't forget to take a single one at least maybe two for the ground. Get some green at least.

Guessing your not installing over current feeding the panel itself. You bought a main lug only 3 phase panel ?

If I get subpoenaed, I say I told him. I try to not overrule. You can lead a horse to water, making him drink involves sucking on his backside. I'm not doing that.

[Oscar]

Technically I didn't say anything. I only said what I needed to say to rile your feathers because I know what you assume.

[Oscar]

If I get subpoenaed, I say I told him. I try to not overrule. You can lead a horse to water, making him drink involves sucking on his backside. I'm not doing that.

Billy,

Try not to faint.....scroll down very verrryyy slowlyyyy.......






































































We had to guess at the length, but looks to be about 120-130 ft.








You're such a drama queen Billy.

[scsmith42]

36 bucks for 120 feet of 2/0 is a steal.

[Oscar]

36 bucks for 120 feet of 2/0 is a steal.

I haven't actually measured it yet, but even if it's 90ft I'll be happy, and so will my RPC.

[Willie B]

Billy,

Try not to faint.....scroll down very verrryyy slowlyyyy.......






































































We had to guess at the length, but looks to be about 120-130 ft.








You're such a drama queen Billy.

Who to HELL is Billy?

[danielplace]

You stole the wire for sure. Good deal man.

What are you pulling for a ground ?

You running it in some EMT, PVC or Greenfield/Flex ?