How to Wire a Rotary Phase Converter the Old-School Way!

Today we're going to assemble and wire up a new American Rotary 5 horsepower phase converter for a maybe-soon-to-be-delivered surface grinder. That's a story for another day.

For the electrical connections, we're going to bolt together ring terminals and insulate with varnished cambric tape, rubber sealing tape, and Scotch Super 33+. We'll also mount a twist-lock receptacle in the panel to make it easy to attach the machine.

Tools and parts used in this video:
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Licensed under Creative Commons: By Attribution 3.0 License

00:00 Intro
00:41 What is a Rotary Phase Converter?
02:11 Routing the wires
04:42 Connecting the idler
08:55 Labeling the wires for the next person (me)
09:52 Mounting the twist-lock receptacle
10:41 Connecting the input and output
12:34 Testing voltages
14:31 Conclusion

[mike]

at 4:17 and noticed the wires have their number printed on the insulation. wonder if he'll notice, heh.
edit: looks like he didn't notice. at 4:17 you can see the 7 on the red wire and the 2 printed on the white wire.

[HomebrewHorsepower]

My first machine tool shipping story. I bought a 1966 Springfield lathe on eBay for $500. I drove to Carson City and trailered the 6000 pound machine back to Boise. When I got it home, I attempted to lift it off the trailer using my 9000 pound automotive 2 post lift. Unfortunately, I did not think through my rigging, and the side load on the lift ended up cracking my concrete floor. We ended up rolling it down off the trailer using ramps and pipes, after which I had to remove my automotive lift and jackhammer out that whole section of my garage floor so I could repour a fresh, reinforced pad.

[dasworkshop]

I've taken "flags" of the self-vulcanizing tape and wrapped each wire individually. Then over-wrap those wires with more self-v tape to form a true water tight connection. If you don't do them individually first, there is a direct path for water/air/corrosion where the wires meet along their length.

[Teklectic]

As someone who repairs things for a living, thank you for documenting your work! So many times projects and repairs are slowed or stopped by a lack of documentation!

[Ropetangler]

Enjoyed the video as usual James, and here is my "shipping story". Some years ago now I worked for a time on The Bass Link Project, an under sea power link connecting the State of Victoria to the State of Tasmania here in South Eastern Australia. The power could go either way between the states of Victoria and Tasmania, and though Tasmania is much smaller than Victoria, we had a pretty well all hydro electric system while Victoria had brown coal fired generators. The idea was that as our hydro stations could go from shut down to full output in a minute or so, and then be shut back down just as quickly, as the load reduced, they would be just the ticket for augmenting Victorias peak load demand, as their coal fired generators would be damaged if they were cycled up and down in output, they were basically designed for a constant output. Tasmania was to supply the peak loads, and Victoria was to supply the base loads for both States. This project involved transmission lines and huge substations where in Victoria 500KV 3 phase was rectified to DC, then sent via the under sea cable to Tasmania, where it was converted back to AC and injected into the Tasmanian network at 250 KV. When Power was being sent from Tasmania to Victoria, the opposite occurred, 250KV was rectified to DC, sent to Victoria where it was reconverted to AC at 500 KV for the Victorian distribution system.
All this involved numerous huge transformers, which came out to Australia from Seimens in Germany, and indeed Seimens were the principal contractors for the project. Seven of these transformers along with lots of other equipment came out by ship, and while the ship was travelling through the Great Australian Bight, she ran into some very rough weather, and was nearly capsized. Fortunately all the equipment must have been well secured, as when it landed initially everything looked OK. One of these transformers, weighing if I recall correctly, 275 tonnes was destined for Tasmania, and was duly delivered on site, where it sat till they were ready to install it. When the time came, a huge rig arrived to pick it up and load on to an equally huge trailer featuring 128 wheels, arranged on 32 individually steerable axle sets, 16 on each side each with 4 wheels. There was also a large pusher truck just to make sure that they could get it to where it had to go.
About this time someone decided that they ought to remove an inspection hatch, to check the interior of this transformer, and when they did, they were in for a nasty surprise. The whole set of windings had moved sideways when the cargo ship had been caught in the storm, and on one side the windings were roughly a metre from the wall of the transformer case, but on the opposite side the windings came within 100 mm of the case. The whole thing was rejected, together with the completely unscathed 10, 000 litre coolant oil tank and all the ancillary equipment. When the word got out about our transformer, they checked the other six transformers which were in that shipment, and altogether 5 of the seven transformers were written off. I have no idea of the cost of 275 tonne transformers, it would be more than I will ever see, that's for sure.

[MrWaalkman]

As an oldtimy electrician myself, the three wires taped together in the peckerhead was a dead giveaway. From memory it should be, 1&4 tied to phase "A", 2&5 tied to phase "B", 3&6 tied to phase "C" (or in this case creating the "C" phase) and 7, 8, &9 connected together and tucked away in the peckerhead.

And old-school would involve a lawnmower cord used to spin up the idler shaft as you apply power to the converter. The homemade one in my garage uses a pony motor.

As for your ground wires, your lug should be approved for two conductors, so you should be good.

[thomas.bjorklund]

So happy to live in Sweden, we get three phase (240V between phase and neutral and 400V between phases) directly from the electrical company. Easy to connect and run any type of gear.

[bradley]

I've been using electric motors like that for most of my life - outside of a professional setting of course - and I've never known the terminal box to be called a pecker head. And after watching this video and hearing it 50 times, I'll never forget!

[rpmunlimited]

Worked for a small R and D company in the early 80s that specialized in unusual condition product handling mainly with the plastic bottle industry. Customer wanted a small footprint but tall preform sorter for a tight location and we produced. Loaded in a semi-trailer for the trip across the country and received a call when it arrived that the machine was damaged. Discussed how the unit had been loaded and secured and the receiving officer responded by saying with amount of splintered lumber in the trailer [ the bracing from packing} and the fact the machine was hanging thru the side of the trailer almost to the point of falling out that they believed the trucking co was responsible, they also ordered a replacement unit on the same call.

[blitzroehre]

That 3 phase converter jobbie reminds me of when I did army, we still had the occasional old tube equipment running on a vehicle battery, and there was a very similar, smaller rotary voltage supply to convert 12 or 24v to high voltage in order to power the tubes...

[Mcfly]

I came for the overkill, and I'm never disappointed!

[MartinBanks]

James,
Great video, as always. Thank you.
When preparing the wires for the ferrules the wire the stripper leaves the separated section of insulation on the end of the wire. Take this insulation between your thumb and fore finger and roll it to twist the copper strands of the wire into a tighter helix. This will allow you to slide the wire into the ferrule without any strands spreading out and coming adrift. Total over kill, of course, but much underrated.

[jpcallan]

I admire your use of ferrules on the stranded wire. I use them too - they make for a much more tidy and dependable connection. The devices you refer to as aluminum screw-terminals are technically known as box-lugs.

[peterfox]

To be honest I would have used Wago Lever Nuts. As the idler is just a three phase motor without a shaft there is very little vibration. In a small shop it is unlikely to see enough use to ever wear out the bearings let alone wear out a lever nut an cause failure. For average small three phase motors in non severe service they have become go to.

That said it was a good demonstration of motor lead connection and insulation. I have done the same many times building new industrial equipment. My only recommendation would be to stretch the 130C tape more. I was taught to stretch it to twice its original length and wrap it tightly in half lapped layers until the shape of the terminals and bolt are no longer distinguishable. You use about the same amount of tape but end up with a dense void free ball around the splice. Additionally the outer cover with electrical tape is mainly to prevent the individual splices from getting stock together as the tape vulcanizes.

For you dilemma of two wire into one ground lug. The best option if they are both the same size is to use an appropriately sized double or twin wire ferrule. Putting two individually wire ferruled or un-ferruled is fine as long as the lug or termination point is rated for it and the lug in you unit probably is (most set screw type lugs and ground terminal bars in that size range are from what I have seen).

Lastly as mentioned previously modern small three phase motor leads almost always have the wire numbers printed along the entire length of the wire. If you ever have a motor with no identifying marks it can be recovered but it is a bit involved as part of the process involves powering up individual windings while measuring voltage on other windings to determine the correct phasing of them. Not a big deal but tedious especially if it is a large motor.

[donmckee]

I've been working with industrial control systems for 35-40 years, and I think every electrician I've ever worked with has called the motor junction box the "peckerhead".

About 33 years ago I worked for a small company in NE Iowa that made the equipment that makes concrete pipe. We were installing a new machine in a plant in Delaware. Part of this equipment was a 110' clear span bridge crane. While the crane was being installed, the rigging failed, and the crane fell. The only casualties were the crane and the turntable of our machine. I'm told that the insurance company wound up chartering a cargo 747 to air-freight the replacement crane from the manufacturer in Germany.

About 10 years later I was working on installing a new 400Hp twin-screw extrusion system in Chicago. The extruder was built in Switzerland and airfreighted to O'hare International. The moving company dropped the extruder while transferring it from aircraft to the waiting truck.

About 4-5 years ago I was installing a new production line for my current employer. Part of this was replacing the 50-60 year old electrical system on 6 floors of a 100+ year old building. This involved installing a number of Allen-Bradley MCC sections. When the electricians were taking the shrink-wrap off of one of the units they noticed something strange and called me over to look at it. There was obvious damage to the unit, but it had been re-wrapped by somebody to hide the damage. We wound up eating the damages to that unit.

Don

[jfl-mwrp]

For many years my grandfather just pull started his 5 hp motor used as a phase generator. Nothing else needed. Capacitors and voltage switches only make it self starting. 😁

[jimdean]

My most memorable shipping story was actually yours when you got your first PM mill. I ordered a similiar mill and was anxiously hoping it would not show up in the same condition. It didn’t but there were other issues which is another story.

[gofastwclass]

Nice install. My 10 HP American Rotary ADX wall mount had tags and numbers on the idler wires. In the two years I've owned it, I've had it apart only to check connections after the first month and relocate the panel. It runs all my machines and has been rock solid.

[Blackcountrysteam]

James I recon with your resources you should have printed a terminal block but having not done so your insulating of the connections even by your high standards was well over the top 😀

[jackpledger]

Been using an American Rotary 15 hp converter in my shop for 6 years. Never had a problem...even run a Haas CNC Mini mill with it.