WTB -- 3 phase motor

[Ralph Steffey]

Does anyone have an extra 15 or 20 hp 3 phase motor for sale? I will be at the swap meet this weekend.

[Tim Morton]

You might want to modify the topic and add...WTB, just to clarify your needing a motor.

[Ken Salisbury]

You might want to modify the topic and add...WTB, just to clarify your needing a motor.

I did that for him

[Ralph Steffey]

Thank you ken

[Greg Mann]

Does anyone have an extra 15 or 20 hp 3 phase motor for sale? I will be at the swap meet this weekend.

That's some serious motorin', Ralph. If you don't mind my asking, what's it for?

Greg

[Dev Emch]

Ralph...

You wouldn't be making a phase converter by any chance would you

[Rob Russell]

I have a 15HP US Motors motor that I'm not going to use. I'll PM you.

[lou sansone]

yea


what is that big motor for anyway....

lou

[Nick Mitchell]

Wide belt sander is my guess.


If we're guessin'....!

[Ralph Steffey]

Dev you figured it out. I am trying to get my 16 in oliver jointer up and running and it has a 7.5 hp motor on it and I also have a old powermatic tablesaw with a 5 hp 3 phase I want to run.

[Rich Tesoroni]

Do you need to go that big with the rotary converter considering the machines to be run?

I bought and ended up selling a 10HP converter because it needed a pair of 50amp breakers. What would a 15HP converter need?

Rich

[Dev Emch]

Well, the smallest idler motor I would recommend is twice the horse power on your jointer. So that would be about a 15 hp motor.

A world of caution. Not all converters are the same. Some applications are easy start and some applications are hard start. A table saw, for example, is an easy start. Getting that thin blade going is not a difficult thing. The jointer on the other hand is a hard start. You have a 5 inch diameter cutter head which is 16 inches long and its directly coupled to the motor. In fact, there are only two bearings in this jointer. The inboard and outboard bearing both of which support the cutter head in the yoke. The motor has no bearings and its rotor is supported by the cutter head and it is cantelevered into the stator windings. So getting this steel log to spin takes some effort, hence, its a hard start.

So the true definition of a phase converter according to kay industries, the inventor of the rotary converter, is that your idler is two times your rated capacity. So a phase converter with a 15 HP idler motor is actually a 7.5 HP phase converter. Now you can start much larger loads than 7.5 HP if they are easy starts. But for the jointer, your not going much over 7.5 if the starts are hard starts.

How much breaker do you need? Well, that depends on how your converter is hooked up. Regardless of how, the converter needs to be protected from itself. So if you use two slots in your main service center to run all of your three phase applications, then your going to need a disconnect box with slow blow fuses to protect and to turn on/off the phase converter. In this application, L1 and L2 come straight off your double pole breaker. They feed directly into your three phase bus as L1 and L2. Two parallel lines come off these two connections and lead into a disconnect box. When the box lever is pulled down, electricity goes through the slow blow fuses and directly into your phase converter. The output of the phase converter is L3 and it forms the last supply line to your three phase bus. You now have L1, L2 and L3. Current loads on L1 and L2 will contain both the application load and the phase conversion load. L3 will fluctuate depending on what applications are out there. There are cases where the current on L3 can move in both directions. I would wish not to get into that at this point as it can get deep! The point is that here your breakers have to serve both the application load and the converter and you need to protect the converter through the slow blow fuse stage.

Another way of hooking up a converter is to use two double pole breakers and a three phase sub panel. This is the best way of doing it. Now pay attention. The first pair of double pole breakers will feed L1 and L2 directly by going into the outer lugs of a three phase service panel. The second double pole breaker will be sized according to the maximum current load of the converter. See your manf. suggestions on this. For my converter which uses a 30 HP idler motor, my converter breaker is 60 amps. The output of the converter is L3 and it ties into the third center lug of the three phase service panel.

At this point, you just wire up your three phase machine as you would in any standard three phase service center. The breaker is actually a 3 pole breaker now instead of a one or two pole breaker. For simplicity sake, lets assume that you hook up each machine to its own breaker which you should do under industrial code. I will not say anything about using three phase bus lines to daisy chain machines! One of the first things folks notice is that the supply lines for L1 and L2 are massive copper lines and the L3 is nothing but a tiny #6 gage copper line. The other two are 00 gage copper. Whats up with that?????? Shouldn't the L3 also be #00 gage copper?

Good Question. The output of L3 from the converter is protection limited by virtue of its own breaker in the single phase service center. The three phase service center has three back planes. One for L1, one for L2 and one for L3. Each time a machine is started, massive amounts of current are moved from these three back planes through the 3 pole breaker to the machine that is starting. But the third phase or wild leg or L3 contribution is created by the rotary transformer effect of the running but idling idler motor. So the converter is pumping current *INTO* the L3 back plane. When I start the powermatic saw with its 3 HP motor, it will suck down some of this current from the L3 backplane to get itself running. Once running, it is not under any load unless you shove a huge oak plank into it. As long as its spinning without cutting, the motor is in a type of idle state. Guess what kiddies! It is now pumping current *BACK* into the L3 back plane. So if I go to start the oliver jointer with the saw running, current will be sucked down like you dont know how from the L3 backplane to feed the start up pulse requirements of the starting oliver. But to supply this current, you will find that most of the current for this sernio is comming from the phase converter's L3 lead and *SOME* of it is comming from the idle state powermatic saw motor.

So by using a massive three phase service center, I can increase the total amount of continous horse power I can run in my shop. In my case, my phase converter is a 15 HP converter with a 30 HP idler motor. That means I can run a total of 1.5 * 15 or 23 horse power simultaneously. In theory, the largest motor I can start is a 15 HP motor. In practice, I can start 20 horse motors with light loads or 10 horse motors with heavy loads or hard starts. Big air compressors are actually easy to medium starts because the big boys all have compression unloaders for starting.

I will part with a couple of warnings. First, in most of the schemes that you find documented, the L1 and L2 connections remain hot even if the converter is off. Not only should you not touch these but these are where the control circuits of your machines are hooked up. Your starting coil in your table saw's or jointer's mag starter is energized and it will try to start the motor with one leg down. This is why you find many machines from government or aerospace surplus equiped with large boxes that have a large disconnect switch on them. This is a main line disconnect and it will totally remove the machine from the line.

In my own system, I have both a woodworking shop **AND** a metalworking shop. So I need a way to remotely turn on or off the converter from either shop if needed. Thus, I have a 150 amp ABB three phase motor starter with a solid state, adjustable overload relay feeding my three phase service center. A single pole, 15 amp breaker in the single phase service center supplys power to two remote push to start boxes which are just like the ones on any older machine. In fact, they were striped off of older machines being scraped. When I push the start button, it closes the coil in the ABB starter and energizes the L1 and L2 back planes in the three phase service center. The phase converter's 2 pole breaker is actually located inside the three phase service panel. About 2 to 3 seconds later, the phase converter has come up to full speed and the last back plane of the three phase service center is energized. We are now online. Note that three phase service centers can use single, double or triple pole breakers. If I run out of space in my single phase service center for that new saw stop table saw, I cannot use that as an excuse to send it back. I can locate its 2 pole breaker inside the three phase service center and life is good. You have to be careful here as you can loose capacity if you dont organize this mixing of single and multi pole breakers. For example, if I install that saw stop breaker and use up two slots, then the third slot in the sequence is not used. I cannot use it to power up a set of regular shop recepticles as this is the L3 line and it does not have 110 volts between it and the neutral! I could use either the L1 or L2 slots to do this and it would work just fine. Just make sure that only the third pole of 3 pole breakers have access to the L3 back plane!

So this is 'nuff for now. I should post some pictures of all this but I am afraid that Mr. Putin may think these are pictures from one of his rusting U-Boats and come get me

So lets let this stew simmer abit. Then I will tell you about the three pole, 80 amp breaker I have in the three phase service center. Heck, why not. This guy feeds a 30 KVA square D transformer which in turn energizes a third service center. This one controls 440 volt three phase power.

This whole setup evolved over time in a large two car detached garage. I had no intent that it would go professional but I liked the industry code so that helped out. I live in the sticks and so normal three phase power from the power company is a pipe dream. This is the next best thing.

[Ralph Steffey]

Dev thanks for all the info. I think I have it all figured out if I can find a 15 hp motor but you confused me a bit with the 00 gauge wire that is rated for 200 amps and is not needed? I had planned on using 4 gauge to the converter and 8 gauge to the machines is this heavy enough? Also my 16 inch jointer is soft start unlike most of the 116 olivers I have seen that are direct drive mine has the motor mounted outboard on a platforn on the end. It hase dovetail slides to adjust the belt tension and does appear to be origional. If you could send pictures of your converter set up it would be apprieciated I can use all the help I can get

[Ralph Steffey]

Rich I am going to use a 60 amp service for the converter. I considered a 10 hp converter but from what everyone tells me I need at least a 15 to power up that monster 7.5 GE motor on my oliver.

[Dev Emch]

Ralph...

First of all, it sounds like your going to buss the system. In other words, you have a 60 amp breaker supplying the phase converter "BLOCK" which in turn has three wires comming out. These three wires then feed two huble twist lock plugs in your shop and the plugs are wired in parallel. The powermatic plugs into one plug and the oliver plugs into the second plug.

You can do this and many people have done this. But, there are some issues. First, each item on this bus must be rated for the maxium load that this bus can encounter. If you current limit from the single phase side via your service center using a 60 amp double pole breaker and you use 6 gage wire downsteam of the converter, you should be O.K. The wire from the breaker to the converter block should be 4 gage. That would be more than enough for 60 amps. But remember this. The converter is wired in parallel as well. So L1 and L2 are comming off your 60 amp breaker as 4 gage wire. These two then each break off into two leads. I would run the first lead as 4 gage wire into the phase converter. Then, the shunt for each of these comes off as 6 gage wire and that becomes your L1 and L2 rails for your three phase bus. In other wors, L1 and L2 enter the phase converter terminal as 4 gage. Then tie in 6 gage wires to each of these two converter terminals and run those out on the three phase bus. The output of the converter is L3 and it too is 6 gage. This 6 gage L3 then joins the 6 gage L1 and L2 wires to form the L1, L2 L3 supply bus. Remember you will need a fourth wire here called the ground and it is green.

Three phase machines do not need a neutral to work. They work on the relationship of the three supply rails L1, L2 and L3. But for safty sake, you need a ground in case something gets disconnected and you get zapped.

Now, here is the problem with busing your machines. Right now, your current limited all the way out onto your bus. In a worst case situation, the breaker will not disconnect you until it sees a 60 amp load on the single phase side. This 60 amp single phase load includes both your motor loads and the cost of running your converter. Usually, this is an idle motor current as the idler is never mechanically loaded. You can expect about 4 to 6 amps continous load at 220 volts for a 15 HP idler motor.

But hubble twist lock type plugs come in all sorts of sizes and configurations and voltages. For the most part, your running a 4-wire system. I have some 5-wire plugs because I got a good deal on them. The 4th and 5th wire have different uses. The 4th wire is usually your ground and you can leave it at that. I have seen the 5th wire used for a number of things. I have seen it used as a motor ground and the green or 4th wire used as a mechanical ground. This assumes your electrical stuff is isolated with plastic bolts and so on. One older machine like that oliver online will connect these two for the whole shop via the jointers motor start panel. Its bolted to the oliver by metal bolts. No Kidding! Duh!

Another use for the 5th wire is as a neutral. So you can attach a single phase work light to your machine's electrical system or a DRO or whatever. Just remember that this works *ONLY* for L1-neutral and L2-neutral. L3-neutral is ***NOOOOOTTTT*** 110 volts!!! You will make this mistake only once!

Most guys are running 4-wire systems which makes things easier. But now you need to pick voltage and current. Pick 208 or 220 three phase, 4 wire connectors. But now you need to pick the current load such as 20 amps or 30 amps. Thirty amps is about as large as you want to go. Go higher than this and your getting into pin & sleave connectors like the ones used to hook McDonalds french fry machines to the grid. Those are those big blue tubers on the drop cords supplying your favorate french fry emporium.

The problem with using say a 30 amp hubble twist lock connector is that its wired into your bus in parallel and its rated for only 30 amps. Your safety system is rated to 60 amps single phase. So its possible to overload the hubble and **NOT** trip your breakers. This is one issue with the bus topology.

The second issue is the size of wire needed to run the bus. Your going to need to use four THHN #6 gage conductors running the entire length of your bus. Good or Bad? That depends on how big your shop is and how many machines your putting on it. For only a powermatic saw and the oliver jointer, this not that big a deal. Upgrading this will be a big deal. But Ralph will cross that bridge when he gets there and brings home that 24 inch powermatic planer and the 36 inch Moak band saw

So to get around the hubble issue and not have to run 6 gage wire into the machines, here is what you need to do. You need to protect the machines from being overloaded as well and you should try to use nice flexible SO rubber covered cable from the bus connection to the machine connection. Dropping four #6 gage wires into a machine is dangerous and not usually done. Use SO cable for this part.

I would run the main bus as EMT conduit about 3/4 inch to 1 inch in diameter. Check code on fill factor for 4 #6 gage THHN conductors. At each node in the bus, you will have a nice junction box. Run EMT from this junction box into a 60 amp disconnect switch & fuse box. These are those gray boxes with a handle on them. Wire the incoming connections with #6 gage THHN using wire nuts in the juntion box and connecting to terminal screws in the disconnect box. Place three fuses in the disconnect box. Make sure these are slow blow fuses and form factor compatible for 60 amp useage. Check the nameplate rating of your motor and select a fuse size no more than this value! Now, you can size the conductor size for your SO drop cord. For example, if you use 20 amp fuses for the powermatic saw, you can go with 12 gage SO cord. Buy a length of 12-4 SO cord and connect this from the disconnect box to the powermatic's electrical box.

Repeat this process with the jointer. Both will have different size fuses. Now you can bypass the disconnect box by simply running a length of 6-4 SO cord from the junction box into the machine directly. But this is a hunkin fat sized SO cable. You may have issues wedgie-izing the cable into the starter's terminal clips and if the starter is not rated for 60 amps, you can the risk of damaging the starter. There may or may not be an adjunct slow blow fuse block inside the machine. Each one may be different.

If each machine is hooked up on its own circuit with its own protection, then you can almost invariablly use 10 gage THHN to wire the whole shop. I found it cheaper to just go this route and buy 500 foot spools of THNN wire from the elctrical supply companies or home depot. With some exceptions like a 15 HP compressor, everything is just happy on its own 10 gage. 10 gage can run 30 amps. What is the nameplate rating for the oliver jointer?

Now you had mentioned that you wish to use 8 gage to wire the bus. This would be possible but you have a couple of issues. First, you will need to make sure that under no circumstances will more than one machine be used at a time. Second, you will need to install a slow blow buse block or fused disconnect box covering all three main lines of the bus right where the bus begins. You will need to size your fuses based on the maxium allowable current for 8 gage wire. This protection is to protect the bus and to a lessor degree, everything attached to the bus. The 60 amp breaker will not help you here. Its main job is mostly protecting the converter. Each machine will need to be wired with 8 gage. So the drops will be 8-4 SO cord.

It does not matter if the motor is direct connection or pully drive, it will have the same starting issues. What makes a difference is if its soft start or not. In terms of phase conversion, the term HARD START refers to a machine that is fully connected and provides significant mechanical resistance to the motor during start up. Your jointer is a hard start because you cannot disconnect the cutter cylinder which is a log of steel 5 inches in diameter and 16 inches long. You would herniate yourself just picking it up!

The term soft start has nothing to do with phase conversion. A soft start motor is one that has one of two alternate starting schemes. In the first example, you have a solid state VFD running your motor and as it starts up, the alternating current frequency is not 60 hz but ZERO hertz or DC. The system then begins to ramp up the frequency until it gets it up to 60 cycles. This is one of the most humane and finest ways to start a motor.

The other soft start scheme is done by switching the connection of the motor. During start up, the motor is hooked up in a delta configuration and allowed to come up to speed where upon reaching speed, it switches the motor over to the more conventional Y configuration. This is the way Martin machines start up. If you have ever started a newer martin, you would be amazed at the velvety start up sequence. It is not violent at all.