RB,

Like I said I'm pretty new to this. From what I can tell Watts equals volts ampere. Is that correct? So a 24v 50amp power supply would run all three motors. The next options is 24v 75amp. I am confused because you are saying 24v 1 or 2 amp should run one motor. So wouldn't three be run by say a 6 amp?

Thanks,

Jason

 

Thanks for all your help. I didn't smell anything so hopefully I got lucky.

Hopefully you were wearing a 4-leaf clover

It is a Pacific Scientific 5410-010 stepper drive.

I found this thread: http://www.cnczone.com/forums/showthread.php?t=19816
that might lead you to schematics. The last poster apparently downloaded the info a year ago. The link to the schematics is not working, but it might be very helpful for you to communicate with that last poster. There is also a link to Pacific Scientific software for driving the 5400 model; it runs in MS-DOS. You'll probably need a dedicated computer running Windows 98 or earlier OS.

The reason that I got it as a freebie is because it is no longer supported. haha it figures right haha.

It'll be a great learning opportunity

Anyway, I'm going to try to get online with some of these guys that claim they can fix them, and maybe I'll be able to get a connection diagram.

See that thread I linked to.

One more question. What voltage is tx1 putting out. That has been the big question mark in my head since I started this thing. I was thinking 110v ac, it looks like you said 208v ac. Am I reading this right?

OK, the line voltage used was 3-phase 240VAC.
However, the INPUT to TX1 was only two of the three phases. When connected like that, the INPUT voltage is 208VAC.

The transformer had a 5KVA rating, or 5,000 volt-Amperes. The output voltage was not specified. However, it had to be less than the maximum allowed by the drivers.

There is a 25uF cap in the schematic after the bridge rectifier; indicating to me that they weren't concerned about ripple voltage, only transient suppression (in case of a large momentary spike on the line, the cap would absorb some of it).

The 500 Ohm 25W resistor is a "bleeder" resistor to discharge the cap when the power is disconnected. That might provide another clue.
Usually, people use resistors that are rated for at least twice the power that is actually required for reliability. 25W / 2 = 12.5W. E=sqrt(P*R) = 79V, but we already knew that the voltage had to be less than 75. At least we know the resistor is adequately rated for operation at the maximum input voltage of the drivers.

There are two 20A fuses on the output side of the transformer. That's a clue that the 3-driver system drew less than 20A under normal circumstances.

 

Sarge,

wanted to make sure I thanked you for all of the info.
Your insight has taught me a lot just in this one scenario.

 

I hope you post photos of a working machine when you can get it going - that's thanks enough

 

RB,

Like I said I'm pretty new to this. From what I can tell Watts equals volts ampere. Is that correct? So a 24v 50amp power supply would run all three motors. The next options is 24v 75amp. I am confused because you are saying 24v 1 or 2 amp should run one motor. So wouldn't three be run by say a 6 amp?
...

That is correct. If you provide the physical dimensions of the stepper motors I can say more exactly what their wattage will be. It's always determined by their physical size.

Generally speaking 20 watts of PSU per motor should be plenty. Exceptions would be if the motors are huge and/or the size and type of machine you plan on driving, but you haven't given much of that information...

 

Rb,

The motors are 4.5 x 4.5 x 7.5 inches. They have a .75inch output shaft. I am planning on building a 4 foot by 4 ft table.

 

I’ve just looked at you diagram it is three phase supply coming in to the Unit so supply in is 240 volts The supply therefore on the capacitor assuming that your motors are rated at 65vdc must be 45 volts AC out of the transformer before rectification You work this out by multiplying the voltage out of a transformer through a bridge rectifier to be 45 *1.414 because you effectively double the frequency of 50hz which gives you 100 hz so you get a voltage doubling effect which happens to work out to 1.414 * peak AC voltage probably not the best way to define this but never the the less true Someone else may be able to give you a better explanation than I can

 

I’ve just looked at you diagram it is three phase supply coming in to the Unit so supply in is 240 volts

Incorrect. Phase-to-phase voltage with 240V 3-phase is 208V.

The supply therefore on the capacitor assuming that your motors are rated at 65vdc must be 45 volts AC out of the transformer before rectification

I'm wondering how you worked that out.

You work this out by multiplying the voltage out of a transformer

The voltage out of the transformer is an unknown. The 5kVA rating is a known.

through a bridge rectifier to be 45 *1.414 because you effectively double the frequency of 50hz

The frequency is unknown, although it's more likely 60Hz than 50Hz as our OP is in the States.

which gives you 100 hz so you get a voltage doubling effect which happens to work out to 1.414 * peak AC voltage probably not the best way to define this but never the the less true Someone else may be able to give you a better explanation than I can

Nice try, but... really.

 

Rb,

The motors are 4.5 x 4.5 x 7.5 inches. They have a .75inch output shaft. I am planning on building a 4 foot by 4 ft table.

Wow! How much did you pay for those massive beasts?

Nema42 = 108mm square, 5/8" shaft, 12.5W/phase (small motor) 18W/phase (long motor) so at full power you need 12.5*1.4 or 18*1.4 depending on the motor length (stack 1, 2 or 3).

But your size sounds larger than that. I haven't actually seen larger than Nema42 in a stepper motor.

Where's your photos??

(edit) Adding web page with Nema42 motor specs and photo;
http://www.totalmotionsystems.co.uk/products/smotors/s1100.html

 

Incorrect. Phase-to-phase voltage with 240V 3-phase is 208V.


I'm wondering how you worked that out.

The voltage out of the transformer is an unknown. The 5kVA rating is a known.

The frequency is unknown, although it's more likely 60Hz than 50Hz as our OP is in the States.

Nice try, but... really.

No the voltage of the transformer out is unknown agree
but the voltage needed to drive the motors is known as to is the current rating

So we can almost certainly deduce that the voltage out of the transformer is going to be in the region of 45 volts to 55 volts That’s a fair assumption wouldn’t you say hmmm

My maths may not be 100% correct but for quick observation it always works roughly 30- 45 years of experience from the age of six has taught me not everything on paper applies to practical experience Hence why university students still don’t know their colour codes for resistance and why so many designers in the industry land up with products returned to the united states

See theoretically they are 100$ correct practically speaking it never ever works out that way Hence why we land up with British soldiers being shot in what the USA terms friendly fire

Not everything in life is absolutely 100% If you need to get a rough idea when you have numerous unknowns then it works

You can only try to be perfect but normally when you do try to be that perfect you end up making terrible mistakes as I dare say you will find out soon enough


Whilst I appreciate I may not be 100% correct practically speaking if you care to carry out this tiny simplistic experiment yourself you will see that applying a 12volt sine wave from a suitable transformer onto a smoothing capacitor through a bridge rectifier does actually lend itself to approximately 15- 18volts DC on the smoothing capacitor which means you do actually get a slight voltage doubling effect Also why you always overate the Smoothing capacitors working Voltage unless of course you want to see smoothing banks erupt due to working voltage has being exceeded

Also if you now inspect most dc adaptors common household units ps “designed by professionals EG Motorola etc ha ha “ and also many American made amplifiers which arrive into the Uk you will find that what they quote as true RMS DC on a 12 volt range is in fact not the case and when you measure this you will find that the output from these is nearly 19 volts when supposedly quoting 12 volts

But perhaps you should try this yourself of course if we wanted to be this critical then you would land up with awful amount of companies going bankrupt wouldn’t you ??? Hmm sometimes you need to be a little more understanding of the world

No offence taken but if you would like to see the photo's of this no problem at all I clearly display this just for you

Last but not least not all of us were lucky enough to receive possibly the education you may have had and from that point of view you would also know that attempting to criticise people in a negative fashion is actually quite nasty However if you know the answers to this and you can demonstrate this both practically and theoretically and you can ensure that your theoretical answers match the practical solution with 100 % accuracy then by all means please show us

Criticism is fine but at least please reply with a positive solution demonstrated with results

Thank you very much anyway

 

RB,

I managed to find the documentation for the motors in the net last night. You are correct, they are nema 42 step 2 motors. I am assuming the output shaft is 5/8 not 3/4 because I just did a quick measurement with a tape measure. If the 5/8 is standard for a Nema 42, then that is probably the case.

These were part of the freebie package, but it looks like I may pay for them when it comes to getting power to them.

 

RB,
So it looks like I need 25.2 watts per motor. 75.6 total. Is that correct.

 

I'm going on my own calculations here, so let me know if I goofed up. I am assuming that 1 watt = 1 va. So if I was going to run 24vdc. I would need 1.05amps per motor. (25.2w/24v=1.05amps.) If this isn't right set me straight please.

 

I'll suggest that you're better off with more capacity than you think you need. Running at 100% capacity may lead to a short service life.

I'll also suggest that the higher the input voltage, the faster you'll be able to step your motors. This is because current flow through the windings starts much more quickly at high voltages than at low voltages.

The motor drivers are most likely of the "chopper driver" type. Once the current through the winding(s) reaches the set peak current, the supply is turned off until the current drops below the peak.

With a chopper driver, you can use a supply voltage that is several times the motor's rated voltage.

Marlin P. Jones & Associates stocks a variety of switching power supplies in various wattage and voltage output ratings. I've used them numerous times in the past; they always shipped very quickly and never had a problem with an order.

Their switching supply page is here:
http://www.mpja.com/products.asp?dept=465&main=1
I'd opt for a 150W supply.

 

Sgt., I have several Pac-Sci stepper driver modules and a few other brands of drivers, and they all state in the owners manuals to use "unregulated power supply" for the motors. They all basically show the same thing as the blue print the O/P showed in the beginning of this thread. Just a transformer, bridge diode, and 25,000μf or higher filter capacitor.

I haven't seen any stepper drives that suggest using a switcher power supply. And I looked at a lot of different brands manuals in my research for my own project.

 

shortbus,

Any chance you have the connection diagrams for a 5410-010 pac sci stepper driver?

 

Good point, shortbus.

This transformer, or a couple of them, would do the trick:
http://www.mpja.com/prodinfo.asp?number=7846+TR
120/240VAC in, 24VAC (12-0-12) CT out @ 10A.
Not bad for under $20.
That's a hard to beat price.

 

Holy cow!

I must me learning something here. That is the type of transformer I have been looking at. I just wasn't sure the 10amp would be enough. Do you think that one transformer would be enough sarge. From what I have gathered through the information posted here, it should be plenty....right?

 

shortbus,

Any chance you have the connection diagrams for a 5410-010 pac sci stepper driver?

The drivers that I have are the Pac-Sci 6410 . I don't know how Pac-Sci is now that Danhler owns them, but before they were very helpful.

I would call them and ask about the 5410. They may send you a copy of the manual. On obsolete items they companies usually have paper work like this on file but you need to ask for it. I've found that a phone call is more effective than a E-mail for this sort of stuff! It's harder for someone to blow off your request when talking on the phone.

Your motors in the print are shown set-up as Bipolars. If need be you could get drivers on Ebay and drive them as Unipolar. If you can't figure out the 5410 drives.

The owners manual for my drives is on the Pac-Sci web site. Now on my drives when you take off the top sheet metal cover, what each connection does is printed beside it on the PCB. Hope this helps.

Cary

 

RB,
So it looks like I need 25.2 watts per motor. 75.6 total. Is that correct.

Yep that's a Nema42. Looking at the amount of laminations on your motor photo it looks to me like a 2-stack. The web link I posted shows 2-stack at length of 189mm so that looks like your motor too.

65v appears to be the rated MAX voltage for the motor! Motors don't display the recommended driver PSU voltage! I would use a lower voltage for the PSU; 24v, or maybe 40v. That is where you need the datasheets for your drivers.

That link I gave shows a motor with similar specs to yours;
7.5A, 0.26ohms, 5.0mH
so that is 7.5*7.5*0.26 = 14.6W / phase.

Your P.S. driver should do half stepping, quarter or microstepping etc so you need average motor current of 1.4 * 14.6W so that is 20.44W actually needed by the motor.

Factor 70% efficiency for the driver so the driver will consume 20.44 / 0.70 = 29W then allow for a power supply with some safe overhead (as SgtWookie said) so you need about 40W PSU per motor, or a 120W total PSU.

If you are going to be running non-stop at high motor speeds and/or loads (like if this is a 8'x4' router for continuous use routing MDF with high radial loads on the spindle) you should bump that value again to 200W or even 250W as the motors consume more power when running fast and/or high loads.

3 motors of that size is not really a "hobby" level project, that is some serious big money hardware! This will need a commercial style "industrial sized" PSU so be prepared to spend $$ including a large metal box and fans etc.

Yep I'm jealous.