I'm planning to build my own PSU.

wonder what dictates the Amp rating of a transformer?

One determine the voltage output of a transformer by the amount of winding, but what says how much max amperage it could deliver? (except for the bridge and capacitor with each has it's own rating). the wire gauge?

I'm no transformer or winding expert, but it will be a combination of factors. The limiting issue is I believe, heat dissipation.

You certainly need sufficient gauge wire, or you'll burn out the wire from heat. I suppose you could do something impractical like immerse it in liquid nitrogen to pull a few more amps out without a meltdown, but that's useless speculation.

Next, you need to insure that the insulation around that wire is stable at your operating temperatures. If you get enough heating during operation to melt the insulation, then the winding shorts, you get more heat, and eventually the wire fails.

It seems to me that the size of the transformer core may influence the range of amperages that can be handled efficiently (I.E. without producing excessive heat), but I'm out of my depth once we talk magnetics.

I know that creating a "magnetic short circuit", for example by using a U shaped bracket and a through bolt with a toroidal transformer is a bad thing to do, but I'm not sure what the failure mode is, which is to say what element of the system regulates the ultimate amount of current flow. It certainly won't work to produce output voltage, but I don't know what element is going to heat up and become unhappy.

Yes, the wire gauge and the mass of the ferrite ring core.

And TYPE of core material, which influences the flux density of the core, and core type (toroid or E-I Lamination) will also be a factor. :)

thanks guys, i guess i just have to delve deeper. hopefully i'll come back informed and able to share. normally i hate anything EM, but for our application i think i'll get away without having to deal with anything too hardcore.

I ended up with the ANtek PS-4N48R12 - Not listed on their site.

I found a transformer with winding that's just nice for G540.
It step down from 220V or 240V to 36V.
Worrying about spike or noise or instable voltage, i soldered my wire to 240V input connector. So if the real source voltage is 220 i'd get a little bit below 36V.
Measured the voltage after the bridge, giving me me around 34.5V.
After fitting in a condensor 15000uF, it gives a very nice 49V.

I'm still looking for ways to make sure voltage doesn't go over 50V. things like a fuse for voltage. is there such a thing?

beware though, when wiring the bridge rectifier make sure you test the conductivity between each combination of any two legs. luckily a friend was there with me and suggest that i do the test first. only two legs were marked, one marked +DC the other AC. It happens that the connection is like an X. Confused with my english?

Square full bridge rectifiers are always "X" connected.

Hi G' - I have a old transformer from a akai vcr which gives me like 20 volts +- 1v

my input voltage on the AC mains is usually 180 to 200 during the day and at night arount 195 to 210

the 20V(DC voltage) was measured during the day.

Now I am planning to use the same transformer for the 24v relays -

I know that most of my proximity switches - ssr's etc will work with this voltage

I was worried if there will be any reliability issues with the mechanical relays due to a lower voltage.

I need your help here.

RGDS
IRfan

Irfan,
What does the datasheet for the relay tell you about coil dropout? There is usually some range of voltage that will work for energizing the coil.

Hi,

I've read all the discussion about sizing the transformer etc etc....

I also have to apologise if I've missed something but....the MotionKing is a 8 wire motor and the Gecko G201V drive cant do Unipolar so how do i connect the motor? I must say that I have a 3.2:1 self designed T5 timming Belt gearbox so I'm looking for reves more than torque!

Regards

John

Irfan, I wouldn't mess with low voltages on mechanical relays. As Heath says, the datasheet will give the theoretical answers, but a chattering relay is not pretty.

Says who?

There is some confusion over the true meaning of "unipolar", which is often used interchanged for "half-coil".

The type of "unipolar" we are talking about for the 8-wire MotionKing, is half-coil, and that is happily done by G201, G202 or G203V drives. (There is no G201V)

Tks for that. I did see this quote. Sorry the G201V was a type-O. It was note#25 by Richards on Wed 27 Aug 2008,23:16. I'm mechanical so this electrical stuff is the biggest challenge fo rme. So it will be safe to order the MotionKing 34HS9801?

Mike, would you agree that there is confusion about using the term "unipolar", which is often used instead of half-coil?

John, it will be safe to order the MotionKing 34HS9801 motors to use with geckodrives G201, G202 or G203V.

Gerald,

Yes, there is a lot of confusion about the terms, Unipolar, Half-Coil, Bipolar Parallel, and Bipolar Series - and a new term that I'm adding today - Bipolar Half-Coil. I've added to the confusion by using those terms very loosely. The term Unipolar, although referring to the way the stepper is driven, also is the term most motor manufacturers use when giving out electrical specifications for a motor. On the Oriental Motor web site, six lead motors have two specifications, Unipolar and Bipolar Series. Eight lead motors have an additional specification, Bipolar Parallel. Each electrical specification has a Holding Torque specification, an Amp specification, an Inductance specification and a Voltage specification. The 32 X SQRT(Inductance) = MAX voltage formula from Mariss at Geckodrive makes the manufacturer's Voltage specification obsolete. Those specifications are very important when selecting a power supply and current limiting resistors on a Geckodrive based system.

Use the Unipolar electrical specifications when using the Half-Coil method of physically connecting the motor to the stepper driver.

When used in a technical sense, the term Unipolar is really a description of how a stepper motor is driven by a Unipolar stepper motor driver. In the same way, the term Bipolar is also a description of how a stepper motor is driven by a Bipolar stepper motor driver. (Right now, as I'm writing this, I have an Oriental Motor CSD2120-T Unipolor stepper driver sitting on my desk next to a Geckodrive G203v Bipolar stepper driver. The CSD2120-T Unipolar driver is vastly inferior in performance when compared to the superior G203v Bipolar driver.)

ALL GECKODRIVE STEPPER DRIVERS ARE BIPOLAR DRIVERS. Of course that means that there are only four motor connections on a Bipolar drive. The user has to decide how he is going to use the motor and then wire the motor appropriately.

That's where the fun begins. A six wire motor can be connected to a Geckodrive by either using a Bipolar Series connection or by using a Bipolar Half-Coil connection. See, I've just added to the confusion by making up a new term, Bipolar Half-Coil, but the term Bipolar Half-Coil more accurately describes both the physical connection to the stepper driver and the method the stepper driver uses to drive the stepper motor.

I wouldn't normally use Bipolar Series connections (except on the test bench when I'm just playing with motors and drivers). Here's why:

- A Bipolar Series connection has 40% MORE holding torque than a Bipolar Half-Coil connection.

- A Bipolar Series connection requires 30% LESS current (Amps) than a Bipolar Half-Coil connection.

- A Bipolar Series connection has 4X MORE inductance than a Bipolar Half-Coil connection.

The inductance specification is the killer. A Bipolar Series connected motor will have very poor performance at high speeds when compared to either a Bipolar Half-Coil connected motor or a Bipolar Parallel connected motor. Some stepper motor applications require high torque at low speeds. For those applications, a Bipolar Series connection is ideal.

I wouldn't normally use Bipolar Parallel connections either. Here's why:

- A Bipolar Parallel connection has 40% MORE holding torque than a Bipolar Half-Coil connection.

- A Bipolar Parallel connection requires 40% MORE current (Amps) than a Bipolar Half-Coil connection.

- A Bipolar Parallel connection has the SAME inductance as a Bipolar Half-Coil connection.

Here, the current specification is the killer. High current means high heat. Lots and lots and lots of heat when the stepper motor is driven at its MAXIMUM voltage. There is really no benefit of wiring an eight-lead motor using Bipolar Parallel connection and then de-rating the voltage or limiting the current. You would end up with the performance closer to Bipolar Half-Coil than to Bipolar Parallel.

I have a bunch of stepper motors on shelves and in drawers - over twenty-five at the latest count, most of which were taken out of obsolete control boxes that I built to control Kodak Series-S photo printers. All except one are six-lead motors. The one exception is an Oriental Motor PK299-F4.5A. It is my "go to" motor when I need maximum performance regardless of the heat. In the future, whenever I need an ungeared stepper motor, I will probably always buy the PK299-F4.5A motor or its little brother, the PK296-F4.5A, but I will wire it Bipolar Half-Coil. That would leave open the option of changing the wiring to Bipolar Parallel if I ever needed 40% more torque and if I had a way of dealing with the heat or I could change the wiring to Bipolar Series if I just needed high torque at low speeds.

So, in summary:

- All Geckodrive stepper drivers are Bipolar stepper drivers.

- When I use the term Unipolar in conjunction with Gecko products, I'm referring to the electrical specifications of the motor - not to the method of driving the motor.

- I use Bipolar Half-Coil connections unless the application would benefit more from Bipolar Series wiring or Bipolar Parallel wiring.

- I use either belt-drive transmissions or gear boxes to get the most Power out of a motor, where Power = Speed X Torque. The added benefit of a geared motor is getting better resolution.

To those who have already wired up their motors using either Bipolar Series or Bipolar Parallel: Don't worry about my opinions. All three wiring methods work. All three wiring methods will give excellent results. All three wiring methods are 100% acceptable - according to your particular needs.

G,

Again thank you. I'm still busy getting prices, damm the stuff is expencive here in NZ, when i have a complete picture in my head i will post a summary in the forum for comment. I just need to say old Rick at Superior bearing is a very help full chap:).

John.

Hi,
could you comment on your setup, what power supply are you using and do you have proximity sensors in your configuration? I was thinking in getting on of those 540´s
Thanks...

Hector, I homebrewed my power supply from parts I had lying around; I had an existing 70v 300va toroidal transformer, but it has an input option for 120 or 240v primary. I wired the 240v primary to my 120v source and thus it's now a 35vac transformer. ;)

Add a 25a bridge on a heatsink, and a big cap (can't recall the spec right now), and I was good to go.

I do have proximity sensors. The G540 has several optoisolated inputs that are just perfect; essentially you use the proxies to pull them down to ground. Since I ended up with 3 wire proxies instead of 2 wire proxies, I have a small auxilliary 12v supply for them.

So could you recomend going with a 540 instead of going with the pmdx-122 & 203V conventional formula...what are the things one would be not getting if chossing the 540 instead? The 540 looks like a reasonable choice the 203V seems like overkill...

Copied from another post today:

Mike, I have a problem with your "bipolar half-coil" wording because I have always called that "unipolar (half-coil)". The reason I choose to insert the term "unipolar" is because of Oriental Motor's spec sheet which gives two sets of ratings for 6-wire motors "bipolar(series)" and "unipolar". For our half-coil connections, we use the inductance & current ratings in the "unipolar" section of the OM data sheet.

Gerald, you are correct in stating that we have all used the term Unipolar (half-coil). You and I know what it means, but I receive dozens of emails every week asking me how I use a Unipolar motor with a Gecko.

I'm afraid that the term "Unipolar" is causing a lot of problems when motors are used with Gecko stepper drivers. The term "Unipolar" has two meaning when used with a stepper motor. Unipolar describes the electrical characteristics of the motor, (Voltage, Current, Inductance, etc.) but it also describes how the power transistors are used when driving the motor.

The term "Bipolar" also describes how the power transistors are used in the stepper driver. All Gecko stepper drives are Bipolar drives.

Half-coil describes a method of connecting the motor to the stepper driver using only four wires instead of the six wires required by a true Unipolar connection.

It can all be very confusing because we use the Unipolar electrical data to size the power supply and current limiting resistors, but we use a Bipolar physical connection when we connect the motor to the driver.

Probably the most proper way to tell someone how to connect a motor and size a power supply would be to tell them to use the Unipolar motor data, but to realize that they are going to use a Bipolar stepper driver; therefore, they only use four wires when connecting the motor to the driver.

Mike, I realised today that "bipolar half-coil" has been mentioned before: :)

http://www.mechmate.com/Forum/messages/15/3339.gif

(From Oriental Motor reference)

There may other things I don't know of, but two major items are 3 axis only,and only 3.5 amps of power.

If your going to use a reduction like I am, then power probably won't be an issue. If you won't be needing a 4th axis ( indexer ) then the the G-540 will most likely work.

My g-540 arrived today, it is actually larger than I thought it would be. My power supply is on its way as are the motors.

Dave

Gerald,

And here I thought that I had coined a new term. Oh well, maybe next time.

HELP !!!!! This is too much! I have tried to understand this a long time now.
My technical english is not good!
Is this right?

Trying to find out how much power supply I need.
5 motors.
Rated current 4 A.
Phase Inductance 5,50 mH

4A x 5 Motors x 0,67 = 13,40 A
5,5mH= 2,3452079 x 32 x 0,75 = 56,28 V

Power supply= 13,4 x 56,28 = 754 Watt ( is this right?? )

I connect directly from power supply to the driver, and on to the motor?
Do I need some components between some places?
Do anyone have a map with all componentes connected?
I thinking buy power supply from USA, and I don noe what I need.
I must have a transformer, from 220-230 to 40-60, which is the drivers should have input.
Is it some transformers I can tuning between 40-60?
Thanks!

4A X 5 motors = 20A total. Depending on how hard you use the motors, 13A to 20A would be required. (Unless I'm certain that I would be under-running the motors, I would use a 20A power supply.)

32 X SQRT(5.5 mH) = 75VDC MAXIMUM. 56V to 75V will work. The higher the voltage, the hotter the motor.

You have the correct formula for wattage, i.e. Volts X Current. So, depending on the Amps that you expect and the Voltage that you select, a power supply capable of handling 750W to 1,500W will be necessary.

A 40VAC transformer would give you about 56VDC. 20A X 40V = 800VA, so you will need a transformer rated around 750VA.

You will need about 20,000 to 30,000 uF capacitance, again depending on how hard you drive those motors. The working voltage of the capacitors should be the power supply's voltage X 125% to 150%.

There are other minor considerations depending on the hertz (50 or 60) and the efficiency of the components, but power supplies for stepper motors do not have to be exact. Stepper motors will run very well with a power supply putting out 100% of the expected voltage and they will still run very well with a power supply putting out 75% of the expected voltage. A CNC router does not normally stress its motors. Most of the time one or more of the motors will be very lightly used.

You will need to carefully study the Gecko stepper driver data sheet. The power supply is connected to pins 1 (Ground) and 2 (Power). The motor is connected to the A, the /A, the B and the /B terminals. DO NOT connect the power supply directly to the motors. The Gecko provides the power to the motors.

www.antekinc.com offers several power supplies that fit your specifications. They have the PS-8N54 (54V @ 800W), the PS-8N63 (63V @ 800W), both voltages in the PS-10Nxx series (1,000W) and both voltages in the PS-15Nxx series (1,500W).

Thanks!
It was good information.
Now, I have learned a little more.

Svein & Mike

There is some confusion here. Svein is going to use the MotionKing drive that accepts AC power input direct direct from a transformer. Mike's advice is based on Geckodrives.

Svein's drive data is in this post:
http://www.mechmate.com/forums/showt...&postcount=108


Svein, you do not need to purchase a "power supply". You only need a transformer between 40 and 60 volts. A 50 volt transformer would be quite common.

The document of Motionking says your transformer current must match the drive current. We don't know how much heat the Motionking drives make, so we cannot guess that a smaller transformer will be okay. Gecko gives the factor 0.67 - for MK the factor must be assumed as 1.0 until we have better information (measurements). Therefore, for 5 drives switched on at the same time, connected to 4 Amp motors, MK says to use a 20 Amp transformer.

See part number 223-8421 from http://no.rs-online.com/web/ as an example. That transformer has two output coils 50V at 10 Amp each, you will put them in parallel to give 50V 20 Amp.

Great! Thanks
It is easy to become confused in here..
That transformer looks good.
Now I understand much more.
I think I will try 50V input on drivers.
Have heard a lot about rs-online, they have probably the rest of elekto parts I need.
Thanks Gerald.

The transformer at RS-Online is made by Nuvotem of Ireland, who sell direct to Norway. See http://www.nuvotem.com/en/contacts/norway.shtml

You can ask them for part no. 1000P1-2-050. Datasheet

Thanks!
I also need a transnational forms of PDMX.
RS has certainly 9V Transformer to PDMX also.
I can connect the AC 50V directly to drivers, but where should I connect 9V transformer?
After that I have 50V and 9V transformer, drivers, PDMX and motors.
I do not need any more componentes to run the machine?
E-stop and limit switch i must have.
Sorry for all the questions!

Transformer to PDMX. Should I write. (on the first line in the last post)
Sorry my bad english!

Need Help Wiring ANTEC PS and G540
 

Brad: Any chance you have good pics of the wiring for your PS and the G540. I am running exactly the same setup (with ANTEC PS-5N39) and am very uncertain of how to wire the PS (both input and output sides)

Thanks Joe

Joe

The G-540 is very simple to wire, The instructions are very good. I was overwhelmed at first, but the more I read the clearer it became. I don't have e-stops wired up yet, so there only three wires I have connected to the G-540, all three to the power supply.

I have connection #11 on the gecko to the positive side of my power supply output.
I have connections #10 and #12 to the negative side of the output of my power supply.

Those are the only wires I have connected to the input side of my G-540. I need to hook up the e-stops on my machine and I will before I have the remote xbox controller working.

As far as the power supply is concerned, have a look at the kitchen table project, That's pretty much what we all used for our wiring set up. One important thing to do is be sure to FUSE THE POWER IN TO THE POWER SUPPLY. Don't ask me how I know, but I will tell you that it cost about $100.:o

Antec has the instructions how to wire the power supply on their web site on the spec sheet.

Dave

Dave: Thanks. Unfortunately, my power supply is the only one (apparently) where the PDF spec sheet doesn't work! However, Mike showed me that the other spec sheets work and I am using one of those. Do you recommend the optional fuse module for the ANTEK PS? If so, I will order one. Does it have to be installed by ANTEK or can I do it?

Joe

Just spoke to John at ANTEK who is sending the fuse module. Self-install is OK. Joe