[whiteriver]

I have a 3 phase 5 axis robot and need to retofit it to single phase. Rotary phase converter not a option. Will use Mach3 to controll.
Current motors and drives are 3 phase.
Looking at going with Steppers and gecko 201's or Dc brushed servos with gecko 320 or 340 drives.
The two larges motors are Fanuc 5F see attached pic for spec. What would be a equivilant size in stepper or dc brushed servo?
I have read over 400 posts here about servos but still don't know how to get from what i got to what i need. Voltage oz/in watts amps. How does it all compare?

Donny

[Al_The_Man]

The motors shown are 6Nm which is equivalent to 850 oz-inch. 2000 rpm max
If you go with a brushed servo you could use the 6Nm figure but remember that AC servo's usually have less inertia so you might want to go to a bit larger if you want the same speed as previously, those robots can really move. Worse case senario is that you may have to drop the acceleration if undersized, there is the usual limitations with steppers once you get up to the high revs.
Al

[Al_The_Man]

By the way did you look into the actual power required?, as 27Kw seems heck of alot as the main load is the motors and they are not that big. It may be worth looking into what you actually need in the way of rotary converter if the robot takes 220 3ph.
As it would save alot of grief retrofitting and it seems you have a good system in place.
Al

[whiteriver]

I had figured out that 6nm =850 oz in. But how does that relate to the rest of the world. That 6nm is torque stall. Not what it produces on average i assume.
If i went with a 2600 oz/in stepper (already have) would that work? If i went with a dc brushed servo. How many volts how many amps? Lets say i look at surplus center or ebay what would i need to find that would be equal to or better?
As for the 27 kw rotary phase converter. Its what a company sized for my application. 480v 20amp 3phase input needed. I can change the input on the transformer to 220 or 240 3 phase. But then i would need bigger fuses going in right? At 240V 3 phase i would need 40amps right?? Which would mean i would need a 80 amp single phase breaker to run it. Still not to sure about 3phase.

Donny

[Al_The_Man]

Just step back and think about this for a moment, lets assume that the main load for the robot power is the motors. Fanuc motors are pretty efficient, so, if you are going to replace them with equal or greater torque assuming they are as efficient as the Fanuc motors, the required (supply) power is going to be the same or greater. Now do you plan on aiming for 40amp at 240 volts? In any event that is no where near 27Kw, so how did the company come up with that figure?
You have the machine, so look at the size (va) of the power required for each servo amp, fusing etc. And attempt to calculate the actual power required.
Agreed the fusing will be doubled for 230 and also you may have to increase wire size where necessary to the transformers, but this is minor compared to a retrofit. Likewise if you find that the power required is within reasonable limits, it is not hard to build your own rotary converter. (see one of my recent posts).
If the robot was working when you purchased it, I would be inclined to persue this route first.
Al

[petek]

another option to look at would be to find drivers for single phase supply and three phase out. I just built a machine and used allen bradley amps/power supplies single phasein and three phase out.Then you could use your existing mtrs.I believe the ones I used were their ultra 3000's.

[whiteriver]

another option to look at would be to find drivers for single phase supply and three phase out. I just built a machine and used allen bradley amps/power supplies single phasein and three phase out.Then you could use your existing mtrs.I believe the ones I used were their ultra 3000's.

If i had to go that way what did those cost you if you don't mind me asking?

Donny

[petek]

If i had to go that way what did those cost you if you don't mind me asking?

Donny

Sorry I bailed out on the topic, but I went out on my own search for my projects yesterday.To answer your question you must understand that Allen Bradley is one of the priciest out there.If I remember they were about 1600.00 ea.The installation req. only hooking up the 230 vac single phase and the logic connections i.e. encoder, enable, and speed referance.They could be configured for step and direction or analog voltage.Cables were also purchased for the encoder and motor connections. Its alot nicer when your using other peoples money.
Pete K.

[whiteriver]

OUCH. Not in my budget. One of the down sides to working for yourself.
I'm optimistic on getting a phase conveter built so i hope to go that route.
Hopefully i can DNC from a win3.1 or xp machine to the RH controller. If I can then it will save tons of time and money. Provided it even fires up and runs.

Donny
:cheers:

[petek]

Getting back to some of your earlier threads you pointed out that you could reconfigure the main transformer to accept the 230 volt primary.I'll bet the only thing the main transformer is there for is to convert the 480 to 230 any way, so if 230 v rotary converter is in the picture you should take the main out of the scheme. Also if your main fuses were 20 amps at 480 and were feeding the primary to the transformer its common practice to over rate these fuses by 300% and as much as 400% because of the inrush to the transformer. Having said that your actual load may be more pallatable than you think.
Pete K

[whiteriver]

Ok It would be nice not to do a full retrofit.
There is a dual stacked servo amp with one breaker on it 250V 15A. I don't know if that is for both amps or just one. They are intergrated into one unit. IT controlls both big 5f servo motors.
The next servo amp is smaller and has 3 removalble fuses at 250V 5A
The last two servo amps are the same size and part number 3 fuses at 250V 3A.

Break down of input to transformer #1 of 3. 480Vac 3 phase Line in to knife switch. Switch to 3 20amp fuses. to contactor, branch goes to power input module and other branch goes to 5kva transformer 30amp fuses out. There are 2 other transformers down the line a 1.1kva f1 20amp f2 10amp and a 1kva f1 10amp. I'll attach a couple marked up pics on what i got. I don't have a manual. They want $150 for them and if i have to tear it all apart then the manuals won't do me any good. If i can get power to it then i will get the manuals in the future.


I guess the reason they say use such a big rotary phase convertor is to double it for stability. Like i said 3 phase is all new to me.

I have a 25hp 3 phase motor laying around i could make a rotary phase converter out of if i knew what i was doing. And if it was the right size.

Thanks again

Donny

[Al_The_Man]

Break down of input to transformer #1 of 3. 480Vac 3 phase Line in to knife switch.
Donny

Is transformer #1 supplying the panel externally, i.e. can it be eliminated if you take the supply directly in to the disconnect (knife switch)?
Al

[whiteriver]

If i am understanding your question. The answer is no.
The power come into the disconnect then to a set of fuse blocks and a contactor then down to transformer #1. Transformer #1 is designated as the servo transformer. Looks like it steps the volts to 250 for the amplifiers.

I did a little looking and found a site that says you divide the amperage required for your aplication by 2.8 to get hp sizing. If I have 20a fuses on my inputs before the disconect 480vac line then i would need 40a fuses to have a 240vac input line? Is that right?
If i divide 2.8x40amp I get 15hp. So at that I would need a 15hp converter. Am I understanding correct?
Below is the text from the site.
(Transformers and electric equipment (welders, lasers, EDM machines, CNC equipment, computers, plating rectifiers, power supplies, etc.) can operate on the Rotary Converter. Use the same formula as for resistive loads to determine the proper size converter to use.)
(Resistive loads must use the Rotary type converter, the Static type should never be used because it would be damaged. There are two methods to determine the HP of the converter to be used. One method is to take the amperage rating of the equipment and divide by 2.8 to find the equivalent HP. The other method is to take the KW rating and multiply times 1.34 or divide by .75 to find the equivalent HP of the equipment.)

Donny

[petek]

You might also consider finding single phase drivers for your existing three phase motors. I just builtamachine using allen bradley drivers single phase supply for three phase output

[Al_The_Man]

I would expect a 15hp rotary converter to be sufficient for this type of application, also remember that 40amp on 240 is not going to be the normal current draw by any means. This is the amount of protection rated for the equipment it is feeding. Fusing is typically sized for around 1.5 times full load current. If the servo transformer feeds all of the servo's then this is going to be your largest load, the control system itself is going to be around 1kva.
Al

[whiteriver]

AL,
I was useing the fuse size as a max. Extra saftey margin ya know. There is a 1.1kva and a 1kva tranformer also but i think one is 240vac and one 120vac.
Here is a link to a 15hp for $675. $21 shipping. Three Phase Store
They also have a panel kit with the caps starter etc for $109.
Panel kit
What do you think of those? Anyone ever had experiance with them?
Or if I picked up a 15hp motor local could you or someone help me size the caps to get a smooth flow on all three legs?

Donny

www.whiterivermfg.com

[Al_The_Man]

This is some of the notes I made and excellent links you need to make and tune your own rotary converter, Preferably get a 4 pole motor rather than the higher speed 2 pole. Also you will need a clamp-on ampmeter and good voltage/multimeter. I opted to design a 240 start/control circuit to keep components to a minimum.
You will need a selection of ONLY oil filled Motor RUN capacitors , the start capacitor can be intermitent operation type.

Typical Converter Tuning:

DANGER: The voltages in a converter are lethal. Carelessness or accidental contact with exposed terminals with the converter turned on or plugged in may lead to severe injury or death. Always turn off and unplug the converter before making "ANY" wiring modifications. When making voltage or current measurements, use only one hand on the probe and keep the other hand away from the equipment.
Keep the work area clear of obstructions and other objects to avoid tripping and coming into accidental contact with live wires.
Typical data from an actual 10hp converter tune up session is shown in the tables below. This data is for a particular motor. Your measurements may vary from these, but the trends and general characteristics in response to changes should be the same.
The process for tuning the converter is as follows:
Wire up the converter with Cp as in the first line of Table 1. Double check the wiring using an ohmmeter to verify that all is connected as per according to the references made in FRW-7.jpg obtained from the dropbox site listed below.
Start up the converter and take some voltage measurements (reference the schematic). They will probably look something like the measurements on the first line (Cp = 50 Cs = Cpf = 0) of table I below. Trouble shoot and make corrections until this much of the converter is working properly.

Turn off the converter and unplug from the wall between capacitance changes as required to perform the following steps:
Add capacitance to gradually increase the value of Cs as shown in Table I below. Make measurements between each addition. Notice that Vbc is increasing faster than Vac. Stop when Vbc is about 1.03 to 1.08 times Vab. 1.08 is better than 1.05.
Add Cs in increments as shown in table I. Notice that Vac increases much more than Vbc.
You may find you need to reduce Cs by a small amount. The goal is to end up with Vac = Vbc = 1.08 Vab within a couple of volts or so. At the same time Icn should be less than the idler motor FLA rating.

Table 1.

Cp Cs Vab Vac Vbc

50 0 233 208 224
100 0 233 212 236
150 0 233 224 246
200 0 237 239 254

-------- Now start adding Cs ------

150 50 237 240 245
150 65 237 242 246
150 80 237 245 247
150 95 237 247 248
150 110 237 249 248

This looks just fine for voltage balance. notice that L1 and L2 are the wires from the plug prior to any other components. The current should be close to the same in L1 and L2 (other than instrumentation
error).

Measure at that point and begin to add Cpf noting the line current in L1 after
each addition. Add another capacitor and measure again. At some point, adding
a capacitor will increase the current. If that was a big capacitor (say 50uF),
remove it and add a smaller one (say 40uF). If the current decreases, leave
that cap on and you are done. If it increases, take that cap off and you are
done.

The converter in this example ended up with a line current of 4.3A with Cpf = 15
uF.
Incoming line current at L1 = 5.2A L2 = 6.1A before adding Cpf.
After adding 15uf cap L1 = 4.3A.

Current measured at converter motor leads at

Ian Ibn Icn
14.1 16.0 21.5 no load
9.0 17.3 14.5 lathe at 5HP running 1000rpm no cutting

Final values selected:

Cp Cs Cpf Vab Vac Vbc
150 110 15 237 249 248
150 110 15 235 242 222 with lathe at 1000rpm

Il1 Ian Ibn Icn
4.3 9.3 17.7 14.3 with lathe at 1000rpm

http://www.metalwebnews.com/howto/ph-conv/ph-conv.html
http://www.metalworking.com/dropbox/...retired_files/ (select FRW-1.jpg to FRW-7.jpg)
My 7hp converter final schematic http://cnczone.com/forums/showthread...tary+converter
Al

[whiteriver]

Thanks Al,
I will look around tommorow and see what i can come up with for a motor. That 25hp i have is just to big for my shop. I'll see if i can find a used 15hp laying around in Spokane.
I am not 100% sure this robot will even fire up and run let alone be able to controll it with gcode once going. I may have to still retrofit it to mach2 or EMC or?
Hate to dump a bunch of money into a phase converter that may be of no use. The rental places want $200 a day to rent a genertor to power it. Thought about just making sure it works that way but thats a pricey waist of money.

Donny

[Al_The_Man]

Hate to dump a bunch of money into a phase converter that may be of no use.
Donny

Phone around the motor rewind/supply houses in your area for a good used motor, if you then don't need it, make up a small control cabinet and make it look half decent you should be able to get your money back at least.
You never know, you may want a 3ph source down the road.
Al

[HuFlungDung]

Al,
What would happen if you attempted to use a VFD for a phase convertor? It could be programmed for fixed 60hz output, I suppose. I don't know how it would react to a highly variable load. Just wondering, as we know that the phasing from any convertor is not exactly to power line spec, either.