max wire length for gecko

[dertsap]

what is the max wire length that i can have from my 201 drivers to the motors , ive changed my wires over to this stuff http://cgi.ebay.com/CNC-stepper-moto...QQcmdZViewItem

the motors don t seem to have the same power they did before ,and are unpredictably loosing steps and the torque doesn t seem the same , it just isn t the same as it was before , the motors are 6amp and the length of the motor cables are roughly 20 feet, ive come to two conclusions ,the cables are too long or the cables are garbage

any ideas or input ?

[dertsap]

so it s not the new wires causing the trouble

can anyone tell me how to make sense of this :
i went out into the workshop cranked up the electric heater and turned on the router table without the router (spindle) running, i tested a few programs at high speeds to test the system ,everything worked perfectly ,then while i was running another test program i looked over at the heater and figured it was warm enough to turn it off , everything crapped out .started loosing steps and sounded ugly , plugged the heater back in and all was good again ????

now i haven t finished the wiring in the shop ,everything is wired but connects to an extension cord because i haven t added a sub panel yet, its been like this for quite some time now and ive never had any problem ,
i can see running a 1500w heater ,400w of lights , pc/monitor , and two heavy power supplies putting a draw on the power line and screwing things up but its the opposite ,the 1500w heater is whats keeping things stable ?

i don t get it ?
i really don t want to have to run the heater in there in the summer time , it would be a freaking sauna

does this make any sense ? the only thing different from before is the new motor wires and the stupid heater

[Greolt]

Originally Posted by dertsap ........ ive changed my wires over to this stuff......... .............. the motors are 6amp and the length of the motor cables are roughly 20 feet,..........

I googled a couple of wires sizing charts and it seems to me that 22ga is too small for 6 amps

No idea whats with the heater thing.

Greg

[dertsap]

what would be a recommended size for that kind of amperage ,
the wire i had before was the thickest thing i could shove into the driver but it was bulky
what floors me is i had the system running near top speed tonite with all the same torque it ever had , up until i unplugged the stupid heater , i dont get it !
i'm going to try the old wire again and see whats going to happens
its been a while since ive run the system and ive done some cleaning up of the wiring . its got to be the wires

i would really like to understand what in the twilight zone is happening out there,

[epineh]

The only thing I could see the heater doing in this case would be to increase the load on your extension cord dramatically, which will result in a voltage drop for everything plugged in, which as you say should generally cause more problems than it fixes.

Only other thing is that if everything is plugged into the same lead the heater MAY be absorbing some kind of noise on the line caused by the router or power supplies. I am clutching at straws here it certainly is a strange one.

Are you using switchmode pwr supplies by any chance ? I'm not too sure how you set up the current on Gecko's but did you do this with the heater on or off, I wonder if that could affect things...

Russell.

[dertsap]

the router wasn t running to create any noise ,i was only test running the steppers , the power supplies are linear supplies that ive had connected for some time now , i haven t had any problems running this before now , ive recently mounted the drivers and breakout board into a pc box , and using the old pc supply for the logic and the fans , the 24v supplies are on the exterior and isolated from the box

[epineh]

Well there is only one thing it can be then...Gremlins, try to keep a light on, they hate that, the dull glow of the heater may have been keeping them at bay.

[dertsap]

Originally Posted by epineh Well there is only one thing it can be then...Gremlins, try to keep a light on, they hate that, the dull glow of the heater may have been keeping them at bay.

thats gotta be it lol

time to go back to what worked before

[dertsap]

is it possible that with the heater running the power supplies are not pushing out the full amperage and the setup has found a sort of comfort point
i'm just thinking if the drivers are pushing the amperage but power is heavily restricted because of the wires and the supplies are pushing less power to the drivers it has balanced things out
i'm in doubt about it and it probably makes no sense what i am trying to get at,
but whats happening doesn t make much sense either
i just want to be more definite before i go tearing thru all the wiring again

[ger21]

Originally Posted by Greolt I googled a couple of wires sizing charts and it seems to me that 22ga is too small for 6 amps

I dug up some info from Mariss from his Geckodrive Yahoo group.

Most will agree 22-gage wire is pretty small (0.64mm or 0.025" diameter). Let's see how it would work out wiring to a 7A per phase motor 10' (3m) away. 22-gage wire has 0.16 Ohms resistance for a 10' length. Two wires are needed per coil so that's 0.32 Ohms. The voltage drop will be 2.2V due to wire resistance at 7A. If your power supply voltage was 65VDC then it just became a 63VDC supply as far as the motor is concerned. Will your motor know the difference? Not at all; it draws 7A at low speed where supply voltage doesn't matter. At high speed your motor phase current drops to 3A. The cable drop becomes 1V, the supply becomes 64VDC instead of 65VDC. Does the motor care? Not at all again. Will the cable melt? Cable dissipation is 7^2 times 0.32 or 15 Watts. That works out to about 1/8W per inch. It will be warm but not hot. At high speed it's 3W and 0.024W / inch. Not even warm. Mariss

[dertsap]

thanks Ger , i bought some new 14 gage wire which is the same as ive had connected before ,so hopefully it'll be back to normal
the other wire will be good for limit switches (whenever i get to that)

[Greolt]

Originally Posted by ger21 I dug up some info from Mariss from his Geckodrive Yahoo group.

That"s good info. Thanks Gerry