30HP TEMCo Rotary Phase Converter & 45 KVA 460v Transformer

Today I reconditioned and installed a (used) 30 HP TEMCo Rotary Phase Converter in the Monster Shop. This unit came out of a marble/granite fabricator's shop and was packed with stone dust and grease. I replaced the bearings while I had it apart, and at least it's clean inside now! #EngineersWorkshop #machining #KearneyTrecker #milling

[@BROCKWOOD64]

2 things about the fuse box from an electric co. substation person perspective: 1. Source should be the top side. 2. Place a couple of extra fuses in the bottom of the cabinet. One more from the same perspective: The standard is - there is no standard. This equates to Never assume Anything! Oh, as far as bending large wire - just use an appropriate box end wrench or 2. Good score & progress! The basic reason for your higher voltage at the idler motor is the capacitor bank in the phase converter. by improving the power factor the apparent voltage reads higher. It'll come back down when you put a motor load (inductive) on it.

[@EngineersWorkshop]

Thank you for the tips. The breakers are inadequate to toggle the load of the 30hp motor on. I need a real starter. Once I obtain one reasonably priced. I'll get back on this project.

[@boblynch7348]

Well done and well explained. Thanks.

[@EngineersWorkshop]

Glad you enjoyed this.

[@craigtate5930]

What a great thing to stumble upon

[@EngineersWorkshop]

Maybe a butt warmer for cold winter shop days?

[@johnfriend240]

A little bigger than the Baldor on my 2 KVA Ronk RPC. Your high mystery current is probably explained in the Ronk instructions: "When the ROTO-CON is running idle (three-phase load shut off), all the capacitor current flows into the rotary transformer. That is why the rotary transformer gets warm to the touch when it is idling. When a load operates, most of the capacitor current now flows to the load instead, so the rotary transformer will actually cool down under load. Due to the heating effect of the capacitor current, avoid operating the converter at idle for extended periods, if possible. Because the capacitors’ current flows into the rotary transformer at idle, any additional capacitor panels must not be directly connected to the rotary transformer."

[@EngineersWorkshop]

That makes sense. Thanks for your interest!

[@billyhickson1632]

Hi, would a 5HP rotery Three Phase Converter be big enough for a 4.4 KVA EDM machine ? Thank you for any help.!!

[@johnfriend240]

@@billyhickson1632 I'd contact American Rotary with that question. I'm just a dumb mechanical engineer...

[@electromechanicalstuff2602]

Man did u get lucky. Usually finds like that have hodge podge control boxes that one u got looks like I made it. Lol

[@EngineersWorkshop]

The guy's first granite saw came with it. When he upgraded to a bigger saw, he ordered it with a single phase motor. The complete old system is sitting in the barn collecting dirt and bird droppings. I'm glad I rescued this.

[@EngineersWorkshop]

I continued our discussion on a Community post.

[@grumpyoldman5368]

Nice find on the RPC. Disconnect switch (and most other electrical equipment) convention is entry on top lugs so that turning off the switch isolates the fuses. Circulating currents are the reason for the high readings at the motor. There is energy moving between the motor windings and the capacitors (at 60Hz). the inductive and capacitive reactance cause the currents which are not "real" power (as in i and j imaginary numbers). The I2R losses in the wiring are real power and have to be considered for sizing wiring and protective devices. The readings are not apparent power which is different from reactance. If you were able to read power factor at your disconnect switch, you would see that the actual power is probably much lower than the 12A*240V=2.88kw apparent power (kVA).

[@electromechanicalstuff2602]

Agrees

[@EngineersWorkshop]

I knew there were some Sparky's here! Thanks for the info, makes complete sense. I should swap the leads on the disconnect as you specified... might have to buy additional $3/ft wire to do it, but it's a drop in the bucket compared to the 70 ft run I have to do across the building. While you're here I'll pick your brain: was thinking of going across the building with three #2 Cu for the L1, L2 & L3 and using #4 Al for the neutral. This sub panel will be good for 90A for machines on that side of the building. I can put an additional ground rod at that panel (South side of the building); seems to make more sense than a 70 ft ground wire in the conduit with all the others. Your thoughts?

[@electromechanicalstuff2602]

@@EngineersWorkshop why not run it all with aluminum? It's going to a sub panel essentially. That's how I did it. I have a 30 hp RFC and I ran a 2-2-2-2 aluminum service entry wire from RFC to sub panel it's good for 100 amps. #2 thhn copper is good for 130 amps. This rotary phase converter can only put out 27 amps per leg anyways. And if you step it up to 480 first the amperage will be be half that. I only went that big because I wanted every volt possible at my air compressor.

[@EngineersWorkshop]

@electromechanical stuff there are conduits buried in the slab from the building's previous use (sawmill). There is a 1" conduit running straight across under the floor from where my incoming service is to a building column on the far wall. I'm thinking ahead for when I have 460 three phase service: I planned to run 4 wires in that conduit to get 460 + neutral across the building. Maybe it was #3 Cu that gave me 90A capacity (460). I will ultimately relocate my 45 kva transformer there to provide 208 & 120 for outlets on that far wall. Don't really know my tot HP in the future, but want max amps on that side of building in that conduit.

[@electromechanicalstuff2602]

Correction just checked I used 4-4-4-6 service entry wire to sub panel. Good for 75 amps. www.homedepot.com/p/Southwire-By-the-Foot-4-4-4-6-Gray-Stranded-AL-SER-Cable-13100399/205001802 Wire is 90° rated so on the NEC ampacity chart it's good for 75 amps. 75A*1.732*240V÷746W= 41.7 HP * 0.85% efficient= 35.5hp worth of continuous load you can put on 4-4-4-6 wire. Well above what you should ever put on the RFC. Did I mention it's only $1.25/ ft for all 4 wires

[@3cl1]

Did you know you can wrap a bearing in moistened paper towels and microwave it, slips right on.

[@one8bravo785]

There is much discussion of this subject on the practical machinist website.

[@EngineersWorkshop]

I have read much of it, but have not thoroughly researched transformer use as I described.

[@butingtingeverything]

What kind of capacitor your using,, can you tell me the value sir

[@EngineersWorkshop]

The capacitors are glued in place, and i can't see their labels. There are many sources on the web giving starting capacitor values per hp required.

[@diggindiggenit6540]

Nice job on your project esp. the motor clean up, I need to do that to a motor I have that runs Hot on the shell, might be dirty inside or bearings or both, could be about shot won't know until I open it up. Now that 460 your talking about at the end is that considered single phase? Like I have this welder that is single phase and it can use 460v and like you talk about smaller wire less amps required, in my case running the welder at 275A put out it requires 47A 460v or 230V 94A so the 460 cuts it in half, the requirements for amps and of coarse the wire. I watched this video a couple days ago and just the other day was bidding on a several different electric wire (big ones) on pallets, me and another guy drove the price way up, he was going to skate away with pallets of wire for dirt cheap until I started bidding, we went up to 350 then I threw in the towel because I wasn't sure if copper or aluminum and what awg. yeah you are so right about copper wire, just an run from house to my garage of 1/0 copper 3 wire W/ground is like 1500 bucks. I want to do what you doing looking for a motor and maybe a transformer soon.

[@EngineersWorkshop]

When everything is running the 460 would technically be three phase because the idler motor will distribute power to the third transformer. It will be a bit wonky if the balance capacitors aren't perfect, which they never are. Still should be able to run motors wired 460 though. I have a couple motors that are wound dedicated 460 so right now I can't run them until the setup is complete. Thanks for your interest!

[@danielmaciej5764]

I have a scrapping business and I recently picked up a rotary phase converter. It looks like it’s almost brand new! I don’t know what I should do with it. Sell it or scrap it??

[@EngineersWorkshop]

I'd sell it, lots of home shop guys might need one.

[@jmunozar]

I am a sw engineer so this might be a dumb question but I saw you got new sealed bearings; with those you dont need to apply grease to the bearings; correct?. I would imagine those grease points where used in the old times where bearings didnt came sealed?. Is there any advantage to use nowadays open-style bearings vs sealed ones? BTW Thanks for the video! :)

[@EngineersWorkshop]

It's actually hard to find open style bearings anymore, so yes you are correct. Originals were open style and almost all of the new ones are now sealed. They contain just the right amount of grease for a long life and the grease fittings on the motor frame will not be used

[@frankljs]

Im working on a similar project. Were you successful with the 208 to 480? Im looking at used transformers and have been over looking the 480/208 for the 480/240 versions. I wasnt sure i could get to lower voltages (440-480)with the 208. If its doable, I may consider buying one. They are a bit more available in my area. Please let me know thanks!

[@EngineersWorkshop]

The 208Y-120/480 are definitely more available. There was definitely enough adjustability in the winding taps to make the stepped-up voltage come out correct in my case. From comments and investigation by Grumpy Oldman the increments are fairly standard with 12v steps. Check out my subsequent video "Probing 500v" and I think I plotted the available voltages with the steps. I have not run a motor off the high voltage but plan to. I also may use it as a source for unconditioned 460v three phase for a 20hp VFD to power a large Quincy screw compressor.

[@jeremycurkendall5372]

I have a similar issue with the controller being misplaced with all the caps. I have a 30 horse Temco Identical to that and I was wondering if you could tell me the capacity of the start caps and the run caps that would help me here to get my system up and going much appreciate it. Thank you.

[@EngineersWorkshop]

Will try to look at them tonight. As you know, they are glued in place and I don't know if I'll be able to see any of the labels.

[@EngineersWorkshop]

Shoot me an email and I'll send you pics and specs. [e-mail]

[@billyhickson1632]

Hi, would a 5HP rotery Three Phase Converter be big enough for a 4.4 KVA EDM machine ? Thank you for any help.!!

[@EngineersWorkshop]

The rule of thumb i've heard is the converter should be 150% the size of the largest motor to start. 4.4kw is closer to 6ho, so you'd need a 10hp rotary or maybe squeak by with a 7.5hp

[@kooldoozer]

Sounds like a loose fan inside that motor. Never heard the 3rd leg called a ghost leg. Is it more scary than the others?

[@EngineersWorkshop]

Sounds better here 19:29 There isn't a fan, just the fins on the end of the armature. Other youtubers have used the term ghost leg, so I'm just repeating what I've heard before. Maybe its because the voltage is "ghosted" from the L1 & L2. As for the 460, any leg is equally scary!

[@electromechanicalstuff2602]

That's what I've always called the generated leg

[@EngineersWorkshop]

@@electromechanicalstuff2602 Ghost leg, generated leg, artificial leg... how many more can we come up with? ;-)

[@Watchyn_Yarwood]

That's all I've ever heard it called.

[@mudnducs]

I’m not clear. 220 single phase > RPC which is putting out 220 three phase > step up xfmr which will put out 440 three phase? Correct?

[@EngineersWorkshop]

That's the plan. The transformer is technically a step-down transformer, I'm just feeding the LV side with 220. It does work, but I'm currently having issues with the 30hp Baldor. I think it has gotten moisture in the windings and won't start. Draws a lot of current. Going to try a 15hp motor in it's place and megger the windings.

[@mudnducs]

@@EngineersWorkshop I worked as a marine electrician for years. Put some 100-250w heatstrips or some heat lamps on the motor for a couple days. See if meggar readings come up…if the windings are good they most always do. Windings just need to dry out. Keep that motor off the ground. 🙂

[@EngineersWorkshop]

@@mudnducs That is exactly what I intend to do... insulated box and heater fan for a couple days. Agree on elevating the motor off the concrete!

[@mudnducs]

@@EngineersWorkshop Good on ya!!! I’m trying to power up my machine shop too. Man, the prices on a 20-25 hp rpc are ridiculous. Gonna build my own if I can find a 20/25 hp motor. Even used ones are ridiculous. Best of luck to you. (Mech eng. retired)

[@EngineersWorkshop]

I was lucky to get mine used from a gent who replaced it with new eqiipment. He was a marble counter guy so the inside was filled with marble dust. Replaced the bearings straight away. Check HGR Industrial Surplus, they usually have some deals.

[@ricko5123]

Actually I was a bit concerned about how much grease was used and with that amount of dust it only makes it worse. But again, great job. I'm also wondering if VA Power brought in a 2ot service for you and did they stop at the weather head of your building?

[@EngineersWorkshop]

I think I explained this in one of my old videos, but if you look at the three Transformer boxes only one of them is an actual Transformer the other two are dummies. I am told that there is a live phase coming up into each of the dummies.

[@gusc6785]

@@EngineersWorkshop why wouldnt you be able to use a single phase to 3 phase VFD instead for each of your 3 phase motors ?

[@EngineersWorkshop]

At 220v, the vfds are good up to about 5hp. The Monarch lathe is 7.5 HP and I plan to have bigger motors elsewhere

[@gusc6785]

@@EngineersWorkshop ahhhh..thanks.. what were you able to pick up the phase converter for$? if you dont mind me asking ?

[@EngineersWorkshop]

$150 if I recall

[@Orgakoyd]

How much would the power company charge to run a 3 phase supply instead of the single phase you got? And how long was the cable run to your building?

[@EngineersWorkshop]

I imagine the cost is zero, like the single phase. They base the job on the projected load. There was plenty of prep work toward the three phase even with the single phase install. I have a new terminal pole, all three phases brought down, and it is less than 100 ft to the building from the transformer. The real cost for me is internal panels and switchgear to house the three phase. The sawmill was gutted and nothing remained.

[@Orgakoyd]

@@EngineersWorkshop I have to say I personally would have opted for running the 3 phases in the building as soon as I could, especially if there was little to no increase in cost. Wouldn't it be possible to only connect to a single phase inside your building until you were ready to run 3 phase circuit? Of course I don't know all the details of why you chose to do what you did so could be wrong.

[@EngineersWorkshop]

The equipment required is thousands of dollars. I don't have the means financially to do it just yet.

[@Orgakoyd]

@@EngineersWorkshop I understand, thank you for your reply!

[@electromechanicalstuff2602]

Leave the motor low voltage just connect the RFC 3phase load wires to the low voltage side of transformer. Then send the 480 to your load. Don't have to target 460 specifically if it's a 480 transformer. I use transformers as step up all the time it's fine. But if u only feed the transformer with single phase you'll get all kinds of goofy voltages. I'd also have a disconnect between RFC and transformer. Get the RFC started then turn on transformer. Also be prepared for main breaker to potentially trip. Transformers have massive start-up current untill it develops magnetic flux. I didn't hear u say what size breaker you used. If it's 100 amp u may need 125. If you try to start up that motor and transformer at the same time the inrush will probably trip your 200 amp main. Just a guess tho

[@EngineersWorkshop]

Actually I planned to power the transformer L1, L2, and neutral directly from the main panel on a separate 100A breaker. That way I could energize two transformer coils prior to starting the RPC. My idea of putting the motor on the high side requires a starter (which I have) wired on the 460 side with a 110v coil, energized when the RPC disconnect is closed. Otherwise two motor legs would be live when the transformer powers up. Leaving the motor on the LV side is simpler, but I worry about the additional inrush of motor + transformer on the capacitor bank. There's a wicked arc on the contactor when it cuts out, maybe the timer can be adjusted to cut out a few milliseconds sooner. My woodworking shop uses an adjustable time delay relay to cut out the start caps, and the motor definitely isn't up to full speed or I get that same wicked arc, or a loud hum as the generated voltage on L3 comes up.

[@electromechanicalstuff2602]

@@EngineersWorkshop u can't only feed two legs of a three phase transformers. They really don't like it. The arc is normal. If there is a hum the timer is on too long. That's y I suggest u start the RFC then once running the start caps are out of the circuit already so no additional load on that contactor when u start the transformer in step two with additional disconnect between RFC and transformer. What do u mean u have a starter? Do u mean the capacitor bank? They may not be rated for 460 volts. Trying to have the capacitors on the high voltage side will most likely lead to a meltdown. Putting the transfer after the RFC is the "norm" for what your doing.

[@EngineersWorkshop]

@@electromechanicalstuff2602 I understand the caps are on the LV side. My scheme is second breaker energizes two transformer coils and builds their field. RPC disconnect is still off. Turning RPC on connects caps to third transformer leg and simultaneously energizes coil of 460v motor starter, connecting all three motor leads to HiV side of transformer. I can picture what's in my head but may not be describing it accurately.

[@electromechanicalstuff2602]

@@EngineersWorkshop u need the caps on the ghost leg of the motor..that's what balances the voltage. Maybe Im misunderstanding what your trying to do. What your doing is not uncommon. Everyone keeps the whole RFC on the LV side and just feeds the transformer to step it up. BCblock is doing it and so is Abom79 along with many others. I tried feeding a three phase transformer with only two legs and the inrush current was not only higher then normal because the transformer never establishes the proper balanced magnetic flux but also the voltages are all over the place on the high voltage side. I understand your concern with the high inrush trying to start both motor and transformer at the same time. But you won't be so it's ok. I have 100 amp breaker on my RFC to support my inrush. But then a fused disconnect with slow blow 60 amp fuses to protect the RFC.

[@electromechanicalstuff2602]

@@EngineersWorkshop kzbin.info/www/bejne/mGK9dot6ZtuMaMU BCbloc stepping up to 480

[@ricko5123]

As you know since I told you already that I've got my whole shop or garage apart until my back property shop is complete and I have all electrical apart to accommodate for the downsizing in big garage and the lack of power from electrical company. My machines are back to just sitting until I'm done. Ok. Seeyah later.

[@EngineersWorkshop]

I understand and feel your pain about having machines just sitting. I have a few machines doing the same thing myself. Good luck to you in getting everything back up and running, it sounds like it will be a fantastic shop once you're done

[@ricko5123]

@@EngineersWorkshop thanks buddy, it was a beautiful shop but since selling it all and moving to house with property to build a shop and acquiring machinery again but nothing like I had, it's been a journey but at least I still have and bought much more equipment again. Going to run in this decent size garage in the house we bought for about another year or 2 till I can finish the shop out back. Should have my power back and equipment running again in next 30 days but it's coming together. Seeyah buddy. Let me know on those collet change over for the 2d. Finally found my trip dogs for the KT2D rotary, sitting in a box from the move.

[@bcbloc02]

Economic collapse will surely bring the price back down.

[@EngineersWorkshop]

Didn't know you subscribed to that theory... I'm all in myself, bad times coming for sure.

[@andrewsweetman4305]

If you are concerned about cost of copper wire, why not just use aluminum? It’s like half the cost.

[@EngineersWorkshop]

Just trying to flow the most amps that will fit by code in 1" conduit. That means copper.

[@Jameson4327]

Bearings made in China.

[@EngineersWorkshop]

Most are these days