G540 - 4 motor connection problem

[dachopper]

Hi guys,

I have just purchased and installed this (http://www.automationtechnologiesinc.com/products-page/g540-stepper-motor-kits/g540-4-axis-nema23-381ozin-48v7-3a-psu)G540 4 axis kit.

All of the motors, in any combination, seem to work correctly by themselves, or two or three of them plugged into the G540, but as soon as all 4 of them are connected at the same time, I get a fault anywhere from 5 seconds to 30 seconds later.

The motors are 3.5 Amp per phase,
Power supply is 48 Volt 12.5 Amp,
All of the motors have 3.48K resistors installed on their DB9 connectors.

I'm at a loss, but the issue seems to have something to do with power supply, or the resistor setting, as it only ever occurs when 4 motors are connected, sometimes even without moving them.

I've read other threads, which all mention power supply, but then ppl point out 7 Amps should be fine, and I'm not even moving the motors sometimes. I have 18 Gau wire between the power supply and the gecko.

Any thoughts?

Nick

[Neale]

Those resistors should set a motor current of approx 3.5A per motor. Stepper motors draw current even when not moving (to hold position). That's 14A. You are using a switch-mode PSU that probably hard-limits at its rated current - 12.5A. I see a problem here...

[dachopper]

well, I was hoping not, as it was a kit bundled together, and that was the largest power supply they had for those motors.....

Why would a retailer bundle kits that don't work together - all of them have less power than required?

the fault seemed to occur at slow speeds, and not high speeds, and when coasting or reversing direction ( I have the acceleration set very low at the moment )

Rapid Speeds around 5000 - 8000 mm/min on a 10 pitch screw
5000 on the 5 pitch

[Clive S]

Why would a retailer bundle kits that don't work together - all of them have less power than required?

This is exactly the reason that we generally always inform new members never to buy any kits of parts as they are rarely matched

[m_c]

That size power supply should be fine. As these are modern chopper style drives, they won't actually draw the full 3.5A from the power supply unless you are really pushing all the motors hard at speed, which is quite unlikely.

It could however be a problem with the power supply. Ideally I'd connect an oscilloscope over the power supply, and see what is happening with all the motors connected.
You may be able to catch any dip in voltage with a voltmeter, as the dip would likely have to last for a second or two for the drive voltage to drop low enough to cause problems.
Does the power supply have any kind of voltage OK output? it may be worth connecting up a lamp to see if the power supply is shutting down when the problem happens.

[Neale]

As Clive says, the kits are often put together using less than ideal choices of components. In this case, I would guess that the kit uses a switch-mode power supply because these are smaller, lighter, and in particular cheaper than a linear supply, which is the preferred option from a purely technical viewpoint. The linear supply can cope with peak overload without breaking into a sweat where the SMPS can trip internal overload protection. I'm a bit surprised as well that there is a problem, though, but seeing that it appears to be load-related, and is a bit variable suggesting that perhaps it is when all motors are trying to deliver pulses simultaneously which won't happen all the time, maybe it is the PSU. Does seem on the face of it to be the most likely issue. My own machine uses small, cheap SMPS boxes for control circuitry where the load is smaller and well-defined (very cost-effective here) but I use a linear supply for the stepper drivers.

[Clive S]

If I am not mistaken depending on the how the drives are set the motors will draw more current when stationary

[m_c]

I would expect the internal filtering capacitors of the Gecko drives to minimise any harmonics that could cause high instantaneous current use.

However, what I'm wondering is what is the actual fault being caused?

[komatias]

With the 3.5A tuning and your power supply the gecko should work 100% fine. I suspect there is something tripping the chargepump.

What are you using to drive the Gecko? parallel port? Is that conking out and causing the chargepump to go low?

[dachopper]

This is my power supply http://www.automationtechnologiesinc.com/products-page/switching-power-supply/48v12-5a

I have the G540, connected with the DSUB ribbon to UC400ETH controller, then that goes Cat5 cable to a switch, and cat5 to my laptop.

When the fault occurs, the connection between the UC400ETH and Laptop and UCCNC program looks normal ( the G540 disables the servo's from moving, and the UCCNC software shows that the motors are still being told to move without any limit switch activation.
)

I noticed aswell, a little noise from the servo's when they are stationary and they are all connected, but less when there are 1 or 2 or 3 motors connected is this normal?

I've checked the resistors and they are 100% correctly installed, and re-wired the power supply to G5540 + and - with other 14G braded wire last night

[dachopper]

Another thought

To troubleshoot the power supply, I have a Mastech 30 Volt 10 Amp variable DC switching power supply.

Should I plug this in ( although it's only 30 volts, and the other one is 48 volts ) and see if there is a difference?

Nick

[dachopper]

I experimented again with the power supply and g540 , thismorning.

My other power supply, is only 30 Volt max 10 amps, but I can see the current draw on the system was down around 2-3 amps ( don't know how accurate that is ) I could not get the fault with the other system.

I then tried the keeling 48 volt 12.5 amp
with voltmeter on the output, it was steady but faulted at 48 volts, I adjusted the voltage pot to 49.9 volts, again stable, the multimeter coult not detect movement, but the fault happened faster at 50 volts, I dropped voltage to 46 volts, and faulted after 5 minute, then I tried 44 volts, and it took lots of simultaneous input, but it eventually gave a fault at 44 volts, I wound the pot all the way back, so it's now at 42.5 volts, and there was no fault so far.

sound like there is a feedback issue coming from somewhere?

Is there anything I can do to try make it work at 48 / 50 volts

[Clive S]

Personally I would build a toroidal transformer type power supply

[paulus.v]

4x3.5A =14A and you have a 12.5A PSU. Am I missing something?

For a switching power supply you need to be at least 18A.

(edit: I may be wrong here but Leadshine, among others, recommend adding 1/3 more to the rated motor current when using a switching PSU; 4*3.5*4/3=18.66A).

For a linear one you will be fine with 10A.

(edit: a bipolar parallel steppper requires a maximum of 2/3 of the rated amps/phase; 4*3.5*2/3=9.33A).

I would go with a toroidal PSU as Clive said.

[m_c]

4x3.5A =14A and you have a 12.5A PSU. Am I missing something?

In short, yes.

And before I give a Jazz style response about people commenting on things they don't understand, go and read the gecko drive stepper motor basics guide, as they explain quite well all about power supply requirements for stepper drives.

[m_c]

I experimented again with the power supply and g540 , thismorning.

My other power supply, is only 30 Volt max 10 amps, but I can see the current draw on the system was down around 2-3 amps ( don't know how accurate that is ) I could not get the fault with the other system.

I then tried the keeling 48 volt 12.5 amp
with voltmeter on the output, it was steady but faulted at 48 volts, I adjusted the voltage pot to 49.9 volts, again stable, the multimeter coult not detect movement, but the fault happened faster at 50 volts, I dropped voltage to 46 volts, and faulted after 5 minute, then I tried 44 volts, and it took lots of simultaneous input, but it eventually gave a fault at 44 volts, I wound the pot all the way back, so it's now at 42.5 volts, and there was no fault so far.

sound like there is a feedback issue coming from somewhere?

Is there anything I can do to try make it work at 48 / 50 volts

Provided you're remaining below the maximum voltage of the gecko drives, and allowing a reasonable safety margin, it should make no difference.

I can't remember, but are there any LEDs on the G540 to let you know any statuses?

I'd suggest temporarily disabling the chargepump input on the G540, and see if fault still occurs. It could be a noise issue that with the higher power, the G540 isn't seeing a good charge pump signal, so it is disabling all the drives. However if that was the case, I would expect problems with the step/dir signals aswell, however that probably wouldn't be noticeable if you're not actually working the machine to notice a position loss.

[paulus.v]

In short, yes.

And before I give a Jazz style response about people commenting on things they don't understand, go and read the gecko drive stepper motor basics guide, as they explain quite well all about power supply requirements for stepper drives.

Sorry for that, I edited my post to better explain my point of view.

[JAZZCNC]

Jazz style response not sure I like sound of that. . .Lol

Anyway I think the answer is obvious but all of you have failed to RTFM.!!! . . . . . With 3.5A motor current set resistor isn't required.

However I'd still throw that switched mode supply away and build one.!. . . . As well not RTFM you didn't RTFF . . . Because you'd seen said many times NEVER BUY KIT.!! . . :stupid:

EDIT: Just seen this.!!!!!!!


Is there anything I can do to try make it work at 48 / 50 volts

You don't want 50v or even 48V because the Geckos are only rated 50Vdc so doesn't leave big enoigh safety margin. You will KILL the drives quickly if run at this voltage.
44Vdc is about high as would run these drives from safety point of view. The 4-5v differnence will hardly be noticable in performance terms but the Smell of magic smoke will be.!!

If you want higher performance then sell the drives and use 80Vdc Digital drives with 70Vdc and then you'll see difference.! . . .Big one.!!

Gecko's are living on there reputation from years ago but sadly today they are behind in the Digital race.

[Neale]

Anyway I think the answer is obvious but all of you have failed to RTFM.!!! . . . . .

Not quite, Jazz - the problem is reading the Gecko manual. Their kit of current-set resistors includes the 3.48K resistor specifically for this drive. Why they use this daft value is anyone's guess, though. But then, Gecko are also responsible for the widely-quoted max voltage based on motor inductance formula which at best leads people astray - or perhaps it suits their drivers better? I also run Nema23 at 65V via a Chinese digital drive and I'm very happy with it. And a linear/toroidal PSU... And I have complete freedom to choose my own micro-step ratios and motor current at the flick of a DIP switch. Americans buy Gecko because they know that "American (products) are great". The rest of the world is forced to buy on price/performance/reliability alone. Oh, pity the rest of the world.

[JAZZCNC]

Not quite, Jazz - the problem is reading the Gecko manual. Their kit of current-set resistors includes the 3.48K resistor specifically for this drive.

Yes has do lots of other Manufactures who use this type of current limiting but just because resistor is provided doesn't mean you have to use the bloody thing does it.? . . . Only use if required and this motor doesn't require resistor.

Edit: By the way I don't think this is the problem anyway. Personally I'm guessing the PSU is faulty.

[m_c]

Not quite, Jazz - the problem is reading the Gecko manual. Their kit of current-set resistors includes the 3.48K resistor specifically for this drive. Why they use this daft value is anyone's guess, though. But then, Gecko are also responsible for the widely-quoted max voltage based on motor inductance formula which at best leads people astray - or perhaps it suits their drivers better? I also run Nema23 at 65V via a Chinese digital drive and I'm very happy with it. And a linear/toroidal PSU... And I have complete freedom to choose my own micro-step ratios and motor current at the flick of a DIP switch. Americans buy Gecko because they know that "American (products) are great". The rest of the world is forced to buy on price/performance/reliability alone. Oh, pity the rest of the world.

I'm sure they only supply that resistor to minimise people asking how they set 3.5A if they've not got a resistor.

The max voltage based on inductance is a valid figure. You can run higher voltage, however unless you're running the stepper motors at speed, it has no benefit and will do no harm.
Any problem will arise when the motor is spinning fast enough that back emf increases the required voltage to drive the set motor current through the motor windings, to the point where you get diminishing returns for the voltage applied.
The key thing to remember is just because you have a 65V supply, is the motor will rarely see that applied. While stationery the motor should only see the rated stepper motor coil voltage, as there is no back emf to require a higher voltage to get the rated current flowing through the motor windings. It's only as the motor starts turning and back emf increases, that the required voltage increases.
Combine that with the laws of physics, where by power = volts time current, and with a stepper using a couple amps running flat out at maximum voltage, will be getting over one hundred watts of power applied. How long do you think your Nema23 could handle that before overheating and demagnetising?

As I said, that Gecko guide is pretty good. I can remember Marris's posts over on CNC zone where he explained a lot about stepper motors, drives, and the theory behind the figures. He didn't build a very successful business by plucking figures out of no where. Which is essentially what you've done by saying your 65V supply hasn't given you any problems, despite you not understanding the theory behind why it probably really isn't a good idea.

[JAZZCNC]

I'm sure they only supply that resistor to minimise people asking how they set 3.5A if they've not got a resistor.

The max voltage based on inductance is a valid figure. You can run higher voltage, however unless you're running the stepper motors at speed, it has no benefit and will do no harm.
Any problem will arise when the motor is spinning fast enough that back emf increases the required voltage to drive the set motor current through the motor windings, to the point where you get diminishing returns for the voltage applied.
The key thing to remember is just because you have a 65V supply, is the motor will rarely see that applied. While stationery the motor should only see the rated stepper motor coil voltage, as there is no back emf to require a higher voltage to get the rated current flowing through the motor windings. It's only as the motor starts turning and back emf increases, that the required voltage increases.
Combine that with the laws of physics, where by power = volts time current, and with a stepper using a couple amps running flat out at maximum voltage, will be getting over one hundred watts of power applied. How long do you think your Nema23 could handle that before overheating and demagnetising?

As I said, that Gecko guide is pretty good. I can remember Marris's posts over on CNC zone where he explained a lot about stepper motors, drives, and the theory behind the figures. He didn't build a very successful business by plucking figures out of no where. Which is essentially what you've done by saying your 65V supply hasn't given you any problems, despite you not understanding the theory behind why it probably really isn't a good idea.

Moray what you say is correct upto to point.? Can't argue with Laws of Pyhisics and like You I've got Massive respect for Marris.

However what your saying about 65V Killing steppers isn't really valid because takes many years to have this affect and the fact they are cheap as chips make it none starter. I've been running my machine for nearly 8yrs with same motors running 70+Vdc and built many many machines using same setup without any issues. In fact never had single stepper fail or go weak.

Now where it gets fuzzy is when to use the higher voltage.? For milling machine or lathe then it's wasted and like you say not benificial. However for Router then the extra voltage makes all the difference. . . Horses for courses.!!

[m_c]

I'm well aware of the benefits, but how often do the motors run fast enough and long enough to have the full voltage applied?
The only time you'd see problems is during prolonged time at high speed, which even on a router, I'd doubt you'd sustain for long enough. But it's worth bearing in mind, that you could easily destroy a stepper motor very quickly by pushing too far.

Regardless, the point I was making, is before people go stating random figures and dismissing known good advice, understand the reasoning behind those figures and the advice. Just because something works for you, doesn't mean it'll work for others.

[JAZZCNC]

Regardless, the point I was making, is before people go stating random figures and dismissing known good advice, understand the reasoning behind those figures and the advice. Just because something works for you, doesn't mean it'll work for others.

I get your point and I do agree on lot of it.! However your just has guilty the others for dismissing Known Good advise by not listening to or trying to put down experienced people like ME.! . . . Do you think I'd go to the trouble of buying more expenisive transformers and Drives which can handle higher voltages if I didn't KNOW there was benifit in doing so.? . . . . No I wouldn't.
Can I give you the calculations and science behind why then NO I can't.!! . . . . All can tell you is I just build the bloody things and thru lots trial error plus lot of patience found that 70Vdc works better for router than 54Vdc which calcs show for same motor..!! . . . . I don't need pyhisics or calculations to tell me this it's obvious from machines performance and to me that's all that matters.

I liken it to what Manufacturers recommend for Octane rating for engines best performance.!!. . . . . But you don't see many performance cars using fuel from your local esso garage do ya.!!

[Neale]

I'm sure they only supply that resistor to minimise people asking how they set 3.5A if they've not got a resistor.

Probably true! Just slightly puzzled why it's not a round 3.5K, but there we are.


...by plucking figures out of no where. Which is essentially what you've done by saying your 65V supply hasn't given you any problems, despite you not understanding the theory behind why it probably really isn't a good idea.
My problem with those kinds of rule-of-thumb formulae is that they take on a kind of mystical significance, where really they are just a "do this and you won't be far wrong" guideline. In fact, my problem with this one is that I don't see any theoretical basis for it (and I don't think that Ohm's Law and the di/dt stuff has changed that much since I studied it 40-odd years ago). However, I do see a reason why higher voltages can give better performance when used with appropriate drives and settings. I won't use a higher voltage still because that means much more expensive drives and power supplies, and why risk the insulation breakdown in the motor? I won't use a lower voltage because I do not believe that I am unreasonably stressing the motor at 65V as the driver is controlling the motor current for me and any excess power is being dissipated in a fan-cooled heatsink - but I'm going to get faster di/dt hence higher peak initial torque this way, so better performance. Can I quantify this? No, but it costs me very little to do it. I'm still tweaking my new machine but I have every intention of sticking an oscilloscope across various bits of the power supply to see what's happening. I'm interested both in the main PSU ripple given that it's a conventional linear PSU, and what's happening across the motor windings under load, just to see what voltages do appear there in practice.

Good engineering is a compromise. Understanding the trade-offs from both a theoretical and practical perspective is useful if you are going to go outside the "just do it my way and it'll be OK" approach. A lot of forum members here do lack an electronics background and look for advice and help, which they often find. Unfortunately, blindly following a published rule of thumb is a bit like buying a kit of electronic bits - it will probably work but won't be optimum in all but a few cases.

In the OP's case, it sounds as if the PSU is at the source of the problem as all the other bits seem to work. Whether it's a paranoid PSU overload circuit which doesn't like the pulse load of four chopper stepper drivers, or is underspecified, or is faulty, is a bit moot but replacing it, even on a temporary basis, with something that is known good is one way to find out. I would probably try reducing motor current in all four motors as well, if appropriate current-set resistors are to hand, to see if that helps. That might also point to whether it's the PSU.

[John S]

I'm well aware of the benefits, but how often do the motors run fast enough and long enough to have the full voltage applied?
The only time you'd see problems is during prolonged time at high speed, which even on a router, I'd doubt you'd sustain for long enough. But it's worth bearing in mind, that you could easily destroy a stepper motor very quickly by pushing too far.



It's not about maximum speed but percentages of the same.
If your 40v system is running at 1/2 speed on acceleration it probably used 20 volts.
If an 80 volt system is running at half speed it gets 40v and so even in the short distance it can reach the designed acceleration faster.

What we also have to take into account this that the home hobby CNC market has bee around for quite a while now.
Anyone remember the fledgling CAD_CAM_DRO group on Yahoo. I quick look at a stored database tells me it started in December 2003 [ edit 1999 ]

In that time a lot has changed but the same information gets repeated, that's the way of the internet.
Marris was very popular on there and he stated a lot of things that have now moved on.
I remember him being very vocal about Leadshine pinching his designs, this for a basically one man band accusing a large corporation with over 300 just employed in R&D alone ?

Leadshine now have closed loop digital drives and have had they for years whereas Gecko never produced a digital drive, they are all analogue.

The Gecko's might go down well in America as it's a large market and there are a lot of loyal rednecks but by the time you get a Gecko drive over here with the £ to $ shuffle, the 19% import duty and the 20 % VAT you are paying thru the nose for outdated technology.

The outdated 542 drive from Leadshine is a far better drive and for more reliable but as i say even that is now outdated.

Another thing that has slowly impinged on the scene are the switched mode supplies.
It was stated in the early days that they were not as good as a decently designed and made torroid but because they have become more affordable and popular early advise is being ignored.

Fact is a switched mode power supply cannot handle back EMF from motors and the faster they run the more you need that facility.

But they are now being bundled with a set of drives and motors that may well match someones purse but it doesn't mean to say they are a good match machine wise.

Switched mode is fine for logic power supplies that supply 5v / 12v / 24v end of story.

Whilst drives and motors have improved no end with advanced R&D and materials the basics behind them hasn't

Always over spec everything if a drive is running at 50 % it will never get hot, it will never be placed in an overload position and so it will last.
Buy well designed drives that have large heat finned cases for just the previous reasons.

Steer clear of micro based units that for some reason the designed has deemed it will look better if it's the size of a postage stamp.

There are physical limitation in running four 7A rated tracks side by side to a motor, 10 thou spacing whilst looking neat does not meet that criteria.

Above all seer clear of the integral motor and drive units.
It's a fact of life that stepper motors want to run hot and drive want to run cool, so why would some twonk want to bolt them together. Or cram 4 drives onto the smallest possible heat sink that will hold them without one falling off the edge ??

[JAZZCNC]

so why would some twonk want to bolt them together.

TWONK.!! . . . That's word of the day for Me.!! . . . . My days been full of TWONKS . .:hysterical:

[magicniner]

TWONK.!! . . . That's word of the day for Me.!!

My day has been full of Knobsocks :D

[JAZZCNC]

My day has been full of Knobsocks :D

Ah that was Friday.! :thumsup:

[dachopper]

Provided you're remaining below the maximum voltage of the gecko drives, and allowing a reasonable safety margin, it should make no difference.

I can't remember, but are there any LEDs on the G540 to let you know any statuses?

I'd suggest temporarily disabling the chargepump input on the G540, and see if fault still occurs. It could be a noise issue that with the higher power, the G540 isn't seeing a good charge pump signal, so it is disabling all the drives. However if that was the case, I would expect problems with the step/dir signals aswell, however that probably wouldn't be noticeable if you're not actually working the machine to notice a position loss.

The Charge Pump was disabled when the issue began, I enabled it and the issue remained

[dachopper]

Jazz style response not sure I like sound of that. . .Lol

Anyway I think the answer is obvious but all of you have failed to RTFM.!!! . . . . . With 3.5A motor current set resistor isn't required.

However I'd still throw that switched mode supply away and build one.!. . . . As well not RTFM you didn't RTFF . . . Because you'd seen said many times NEVER BUY KIT.!! . . :stupid:

EDIT: Just seen this.!!!!!!!



You don't want 50v or even 48V because the Geckos are only rated 50Vdc so doesn't leave big enoigh safety margin. You will KILL the drives quickly if run at this voltage.
44Vdc is about high as would run these drives from safety point of view. The 4-5v differnence will hardly be noticable in performance terms but the Smell of magic smoke will be.!!

If you want higher performance then sell the drives and use 80Vdc Digital drives with 70Vdc and then you'll see difference.! . . .Big one.!!

Gecko's are living on there reputation from years ago but sadly today they are behind in the Digital race.



I have read the manual, the drive IS DESIGNED to be operated at 50Volts, and already has a 10 volt buffer - it works up to 60 Volts.

I have measures the input voltage and current on the switch mode power and it is rock stable at 48/50/46/42 volts, whatever I set with the resistor

The total system current draw is only around 2.6 to 3.3 Amps - when I hooked it up to my 30 Volt power supply

[m_c]

Ignoring Voltage/Power supply discussions, what is the actual fault you are seeing?

Do the motors stop/stall, the drives fault out...?

[dachopper]

Ignoring Voltage/Power supply discussions, what is the actual fault you are seeing?

Do the motors stop/stall, the drives fault out...?

It's reading the CNC code, then the Gecko unit fault light somes on and that disabled everything

Is seems to happen a lot more - the higher the voltage I set on the switch mode power supply, I thought I had it working on the 42Volt setting, which is the lowest possible, but it stopped 3-4 times around the same area in the workpiece today

I tried to re-do it at slow speed, with slower accelerations and it still stopped - it's not jamming, it's running at about 30% of the jamming speed, it's being turned off because Gecko is giving a fault for some reason. the CNC program is still happily running in the background sending commands out

I switched over to another lower 30 Volt switched power supply that is also half the power ( 300 Watt ) , and I've had to slow down the motors and accelerations even more, as it's now almost half the efficient voltage I need. It seems to be getting through the job, although I had a few missed steps due to high loading at times during the cut sequence - so I've reduced the speed/accel even more

I don't know if it's a power problem, or a geckodrive current draw issue, or voltage issue - mystified

[m_c]

My guess is you have a noise problem, which is made worse by the higher voltage.

I've just had a quick scan of the G540 manual. How have you connected pin 10 and 12 on the G540? Have you tried connecting them with just a short bit wire?

The G540 uses 4 G250s internally, which don't have any form of fault output, so an individual axis fault should not cause the G540 fault light to come on.

[dachopper]

My guess is you have a noise problem, which is made worse by the higher voltage.

I've just had a quick scan of the G540 manual. How have you connected pin 10 and 12 on the G540? Have you tried connecting them with just a short bit wire?

The G540 uses 4 G250s internally, which don't have any form of fault output, so an individual axis fault should not cause the G540 fault light to come on.


I've got a wire - about 2 foot long which is connecting them both together, I'll have a go - and shorten it right up, but I doubt this is the issue, then again, the + and _ wires run right next to this wire at the G540 box. -I heard there was some form of overvoltage protection, so I assumed that was what was faulting.


Wow - I just found this thread..

Guy has exactly the same motors as me, and the same fault.

http://www.cnczone.com/forums/gecko-drives/160760-g540-faults-3-motors-connected.html

[JAZZCNC]

I have read the manual, the drive IS DESIGNED to be operated at 50Volts, and already has a 10 volt buffer - it works up to 60 Volts.

Well that's news to me and I've fitted quite few now.! . . . Think you should read again because in the manual on Gecko web site which I've just been reading to make sure things haven't chenged there are still big warnings about NOT exceeding 50Vdc.!! . . . Which with 48Vdc you will get above with back EMF.

[paulus.v]

Wow - I just found this thread..

Guy has exactly the same motors as me, and the same fault.

http://www.cnczone.com/forums/gecko-drives/160760-g540-faults-3-motors-connected.html

But they fixed the problem in their G540 4 years ago. Is your Gecko that old?

[dachopper]

Well that's news to me and I've fitted quite few now.! . . . Think you should read again because in the manual on Gecko web site which I've just been reading to make sure things haven't chenged there are still big warnings about NOT exceeding 50Vdc.!! . . . Which with 48Vdc you will get above with back EMF.

....

You can't possibly expect a consumer, to read a manual that says use less than 50 Volts, then they purchase a power supply that inputs' less than 48 Volts, even 42 volts, and then say, oy you didn't factory in the manufacturers back EMF effect - there is no mention of this anywhere - but there is mention of of the formula to calculate the ideal voltage, and that is close to 50 volts.

I don' think this is the issue - sounds like I have one of the units with the current set resistor at 8 amps, and because of my application, the overcurrent protection circuit is going off.

Shame because I was told in 2016 by automation tech that they were selling me one of the latest models.... and after reading the 2012 post, they knew about this 4 years ago?

If this is what the problem is..... it sounds absolutely identical to the behaviour I am seeing

[paulus.v]

sounds like I have one of the units with the current set resistor at 8 amps, and because of my application, the overcurrent protection circuit is going off.

Shame because I was told in 2016 by automation tech that they were selling me one of the latest models.... and after reading the 2012 post, they knew about this 4 years ago?

If this is what the problem is..... it sounds absolutely identical to the behaviour I am seeing

It would be easy to check the value of the resistorryou have in the short-circuit protection. But only if they will tell you where to look and for what value.

The posts from #56 to #60 are interesting :joyous: ...Like politicians answering a press conference.

[JAZZCNC]

....

You can't possibly expect a consumer, to read a manual that says use less than 50 Volts, then they purchase a power supply that inputs' less than 48 Volts, even 42 volts, and then say, oy you didn't factory in the manufacturers back EMF effect - there is no mention of this anywhere - but there is mention of of the formula to calculate the ideal voltage, and that is close to 50 volts.


They expect the person fitting the unit to be competent or experienced enough to factor in that certain amount of Back Emf will be produced. It's common knowledge even at DIY level that safety factor is required which is often advised being around 10% less than Max rated voltage.

It's dangerous and foolish to assume that any manufacturer as built in "safety" factor and then Ignore the Warning Given in the Same Manufacturers Manual.!!

It's even MORE FOOLISH to thentry an Rubbish what someone with years of experience is telling you will happen if you run at those Voltages.

Now I should tell you to get stuffed you arrogant "Aussie Bastard" but in the spirit of helping people then I'll just say. Gecko after sales service is legendary so Contact Gecko tell them you your issue and they Will replace/repair the unit for you.

Oh and the Voltage Calculation is just that.? A Calculation based on the Motors parameters and should be used has guide line for Motor Voltage and doesn't mean just because your motor specs calculates that 50V is ideal voltage you can run at this voltage on the drives.!!

[dachopper]

Yeah - I might open it up and see if I can find a serial number or something for the unit, and pass that to Gecko

I think Automation tech are sending Gecko a power supply, ( the same as mine ) to see if they can figure out what the issue is, should be this week sometime, in the meantime, all I can do is hookup the 48 Volt pwr supply and check the amperage, but because it spikes so fast, I don't think it will register on the multimeter

At least I can discount the voltage as the culperate, otherwise the 3 motors or two motors connected would cause the same issue - seems to be current draw related

[dachopper]

They expect the person fitting the unit to be competent or experienced enough to factor in that certain amount of Back Emf will be produced. It's common knowledge even at DIY level that safety factor is required which is often advised being around 10% less than Max rated voltage.

It's dangerous and foolish to assume that any manufacturer as built in "safety" factor and then Ignore the Warning Given in the Same Manufacturers Manual.!!

It's even MORE FOOLISH to thentry an Rubbish what someone with years of experience is telling you will happen if you run at those Voltages.

Now I should tell you to get stuffed you arrogant "Aussie Bastard" but in the spirit of helping people then I'll just say. Gecko after sales service is legendary so Contact Gecko tell them you your issue and they Will replace/repair the unit for you.

Oh and the Voltage Calculation is just that.? A Calculation based on the Motors parameters and should be used has guide line for Motor Voltage and doesn't mean just because your motor specs calculates that 50V is ideal voltage you can run at this voltage on the drives.!!

I'm sorry if I have offended you - I am just getting pissed off that I bought a package of components that don't work together, and I have tried your suggestion of a lower voltage - and it still does not work

However.
If what you say is correct, then why when I run 3 motors at 49 volts, does the system run absolutely flawlessly - no burning, no faults, no issues

Hook up a 4th motor, and fault occurs - directly proportionately to the 4 motor load I believe. Even at 42 Volts it still occurs. - that is 20% safety factor no + the manufacturers' unpublished safety factor that I didn't pluck from my aussie arse either - I gained through the wisdom of the internet


Product technical datasheet - from the manufacturer, and published all over the internet everywhere you purchase the unit from.

"Supply Voltage"

15 - 50 VDC.

That means Supply voltage 15-50VDC.... So far 42V - 50V does not work, so it probably is the current protection issue they identified in 2012

[John S]

2012 ? It's 2017 now. Every body else's drivers are in the bin now and they have moved on. Do yourself a favour, try to get your money back or eBay it and get some modern drives.

[dachopper]

Man, I tried Everything!

The unit is a Sep 2016 model, everything looks intact and tests correctly, I've tried earthing and isolating everything.

Can anyone recommend a linear power supply supplier - or are they all created equal?

Nick

[paulus.v]

When choosing the voltage of an unregulated power supply you have to take in consideration the possible voltage variations of the AC line voltage which are usually +/-10%.

For example a 32V AC toroidal transformer will give you around 44V DC at 230V but 49V DC at 253V

[JAZZCNC]

I'm sorry if I have offended you - I am just getting pissed off that I bought a package of components that don't work together, and I have tried your suggestion of a lower voltage - and it still does not work

However.
If what you say is correct, then why when I run 3 motors at 49 volts, does the system run absolutely flawlessly - no burning, no faults, no issues

Hook up a 4th motor, and fault occurs - directly proportionately to the 4 motor load I believe. Even at 42 Volts it still occurs. - that is 20% safety factor no + the manufacturers' unpublished safety factor that I didn't pluck from my aussie arse either - I gained through the wisdom of the internet


Product technical datasheet - from the manufacturer, and published all over the internet everywhere you purchase the unit from.

"Supply Voltage"

15 - 50 VDC.

That means Supply voltage 15-50VDC.... So far 42V - 50V does not work, so it probably is the current protection issue they identified in 2012

Didn't offened but does frustrate because I wouldn't waste my time posting info trying to help if wasn't sure of what I'm saying so when someone with very little experience then try's to tell me I'm talking bo~%&oxs does slighty piss me off.

Just about every drive on the market as specified operating voltage range just like Gecko have and in theory they should work fine if voltage is within that range.
Now where the problem comes from is the fact Steppers can be and are used in wide range of applications. Lots of these applications will be slow moving or light weight applications so will produce very little inertia or back EMF. Then in which case provided regulated 50V supply is used there won't be any issue.

However for CNC router this isn't the case and inertia pushing gantry from high feeds so will create back emf and push the voltage above the 50v safe limit.! . . Ahh but where using Regulated supply your thinking so no problem. . :yahoo: . . . .Wrong now you create another problem.?
Regulated supplies will have protection built into them so if voltage/current is feed back it clamps the supply and shuts down.! . . . Not good.

So you see it's not so black and white.

Now do your self a favor contact Gecko USA not your supplier and tell them the problem and I'm sure they will help you or advise what it could be.

Or better still do your self Bigger favor and sell it then buy Leadshine AM882 Digital drives and use Unregulated toroidal supply. The difference in machine performance will be night and day and you'll never have any issues.

[paulus.v]

Or better still do your self Bigger favor and sell it then buy Leadshine AM882 Digital drives and use Unregulated toroidal supply. The difference in machine performance will be night and day and you'll never have any issues.

Totally agree! I've got the AM882 drives on his recommendation and I'm very satisfied by their performance. Lower noise and vibrations, better performance at high speeds, software configuration, auto-tunning, etc. And you can give your steppers 60-65V for better performance.

[dachopper]

Totally agree! I've got the AM882 drives on his recommendation and I'm very satisfied by their performance. Lower noise and vibrations, better performance at high speeds, software configuration, auto-tunning, etc. And you can give your steppers 60-65V for better performance.

Well - I've got the G540 working on 30 volts with the 4 motors, I've just had to ramp down the voltage significantly to achieve it.

Looked at the leadshine - are you using a Bob or some other thing to break the sigs out into a useable format to run wires?

I ran the G540 for a 7 hour job, and it completed without any problems, so - apart from the fault causing me to run slower, I'm going to reserve my judgement - hopefully there is a simple fix


I'm going to call Gecko tomorrow and see if I can get anywhere with them.

[paulus.v]

Looked at the leadshine - are you using a Bob or some other thing to break the sigs out into a useable format to run wires?


I'm still using the parallel port with a good BOB.

[dachopper]

Update - I finally skyped tech support, and they have been great.

The problem appears to be the result of several factors, but is related to switching power supply / 4 motor combo / and a setting on the G540

Gecko are testing out a mod to the G540 to see if they can get it to work with this power supply in particular, and the 4 motors I have.

I'll let you know the result incase others have the same issue.

Nick

[A_Camera]

I have read the manual, the drive IS DESIGNED to be operated at 50Volts, and already has a 10 volt buffer - it works up to 60 Volts.

The manual on page 3 says:


CAUTION!
Power supply voltage in excess of 50 VDC will damage the G540.

I would not try with anything near 60V, and would keep the voltage below 50V, since that is the maximum.

[A_Camera]

Update - I finally skyped tech support, and they have been great.

The problem appears to be the result of several factors, but is related to switching power supply / 4 motor combo / and a setting on the G540

Gecko are testing out a mod to the G540 to see if they can get it to work with this power supply in particular, and the 4 motors I have.

I'll let you know the result incase others have the same issue.

Nick

Never the less, as several people already pointed out, that PSU is under powered for 4 x 3.5A motors. Build a torioidal transformer based PSU and you'll never look back...

[John S]

Better still scrap the outdated Gecko and get something at least designed in this century.

[dachopper]

We will see, if the new power supply fixes the problem, I'm happy. If not I will probably try the leadshine the am882 quite cheap now it's no longer made, much different to new em series? . It's by no means a "cheap" change so we will see.

I did get my x axis running at 18,000 mm/min when I changed to the 42 volt pwr from 30 volt, so I should get another increase going to the max 50.

To clarify gecko tech support told me that 48 volt should be fine to use, and anything up to 50 volt should be fine with this system. IE it is designed and tested to run at higher voltages, and downrated to 50 volts for the consumer to avoid issues and to include a large enough safety buffer. Anything that fails below 50 is an anomaly.

[Clive S]

All I can say is you have the 20864syndrome. As was pointed out in the original post kits are very seldom a matched set of parts. Go with AM882 and 68V PS and you will have a different machine .

[dachopper]

Is $40 per am882 a good price?

[Clive S]

Is $40 per am882 a good price?

I would say very good but check the del charge

[paulus.v]

Is $40 per am882 a good price?

I do not think you can get them at that price. Be careful not to get defective units/ factory rejects or something. I got them at $75 with free standard shipping or at additional cost for DHL/UPS

[JAZZCNC]

so I should get another increase going to the max 50.

To clarify gecko tech support told me that 48 volt should be fine to use, and anything up to 50 volt should be fine with this system. IE it is designed and tested to run at higher voltages, and downrated to 50 volts for the consumer to avoid issues and to include a large enough safety buffer. Anything that fails below 50 is an anomaly.

I'll warn you again because don't care what Gecko says, if you run those drives at 50V you will considerably shorten there life.!!

If you can get AM882 for $40 then buy them instantly. Feed them 60v+ and watch your machine dance like never before.