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Power supply in parallel
« on: June 29, 2008, 09:55:37 AM »
Hi, My power supply for my router table is a switching power supply at 24v 6.5A.  Look like it is not powerful enough for this purpose. I have two, can I connect both in parallel to increase current for the motors without damaging my board or power supply themself. Thanks for any advices, Jeff

Offline jimpinder

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Re: Power supply in parallel
« Reply #1 on: June 29, 2008, 01:15:58 PM »
When you say it is not powerful enough, what do you mean.

What are you trying to power.

If your main axis need, say 4 amps each, then power each axis from it's own supply - it makes no difference to the driver cards where the power comes from. As long as the leads to each motor are not interconnected, then you will be fine.

If say your Z axis needs another 2.5 amps, then  use  one of the supplies to power this as well.

I am thinking of powering my x and y axis from 36 volts (Gecko drives) and the Z axis from 24 volts (Routout drive) to see if I can increase speed and reliability on my X and Y.
Not me driving the engine - I'm better looking.
Re: Power supply in parallel
« Reply #2 on: June 29, 2008, 09:46:53 PM »
Hi, thanks for the reply.

My router table have 4 stepper motor, two nema23 425 ounces of torque for the  X axis, one nema23 425 ounces for the Z axis and one nema34 1200 ounces torque for the Y axis. When they move all at the same time, I think my power supply is not powerful enough since it can deliver only 6.5 amp and all motors together would need more then that.

This is my board. :

http://cgi.ebay.com/4-AXIS-CNC-ROUTER-OR-MILL-STEPPER-MOTOR-DRIVER-BOARD_W0QQitemZ230266327652QQihZ013QQcategoryZ78197QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


This is my power supply.:  S82J-15024A1 ( this mean, 150 watts, 24 volts)

http://pdf1.alldatasheet.co.kr/datasheet-pdf/view/152773/OMRON/S82J-15024.html

I have two of these power supply but only one input on my board for the power. I'm just wondering if I could hook up two power supply in parallel in only one input to have more current deliver to my motor. Sometime when the move all together, one or two loose steps but this never happen when only one or two are moving.



Offline jimpinder

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Re: Power supply in parallel
« Reply #3 on: July 01, 2008, 01:04:33 PM »
Yes - well, just fasten them in parrallel - pos to pos and neg to neg.

I would, however, include a fuse in line wtih each supply.
Not me driving the engine - I'm better looking.

Offline da21

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Re: Power supply in parallel
« Reply #4 on: July 01, 2008, 02:24:50 PM »
i would agree your power supply is not capable , given the limited information you have supplyed ,
i would have liked to see a voltage around 35 - 48 v and a current rating of 10 - 15A  , although you do not give the model numbers or ratings of your stepper motors , so it is difficult to comment further .

but as a very crude and quick way , add the current ratings of all the motor windings together and add 20% and that will give you a good starting point for the current capability requirements of your power supply , it's better to have an over rated supply than one to low , it's also usuall to supply them with a voltage of about 5 times the motor voltage rating  , then adjust your stepper motor driver current resistors as per the manual

also simple transformer type power supplys are better suited than switched mode for our uses , and tend to be more reliable long term
 

Dave 

Offline RICH

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Re: Power supply in parallel
« Reply #5 on: July 01, 2008, 11:32:06 PM »
Hmm....
Should the parrallel supplies feed a common capacitor before feeding the board?
RICH
Re: Power supply in parallel
« Reply #6 on: July 02, 2008, 02:37:04 AM »
Hi, my board have a maximum voltage rating of 32 volts.

This is my nema34 motor for the Y axis.   http://www.kelinginc.net/kl34H2120-42-8B.pdf        (1200 ounces)

These are my motors for the Z axis and X axis.   (X axis have 2 motors for the gantry for a total of 3 Nema23)  http://www.kelinginc.net/KL23H286-20-08B.pdf     (425 ounces)

All are connected in series.

I'm just asking since I have 2 similar power supply at 6.5 amp instead of buying one at 12 amp.

Offline jimpinder

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Re: Power supply in parallel
« Reply #7 on: July 02, 2008, 12:08:52 PM »
Yes - we understand - BUT - what is the rating of your motors - mine for instance are - forget the name, because it doesn't matter - 220Ncm, rated at 2.5 amps at 7.5 volts - this is the important bit - and it enables you to work out what power you are likely to need as per da21's post
Not me driving the engine - I'm better looking.
Re: Power supply in parallel
« Reply #8 on: July 02, 2008, 02:35:01 PM »
Click on the link for the PDF file I have posted, everything you need is there, rating, volts, ect.   Thanks

 

Offline da21

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Re: Power supply in parallel
« Reply #9 on: July 02, 2008, 03:16:06 PM »

your motors are rated at an average of 3A per phase , with bipolar windings ( 2 phases ) that means each motor requires 3A x 2 , so thats an average of 6A per motor
so 4 motors @ 6A each , have a maximum rating together of 24A ,  if they happen to be at a worse case situation of requiring maximum current on all motors ( ok it's not going to happen often , but you need to be able to handle this ) .

so your options are a single power supply that can supply 24 A or split your motor supplys between more than one power supply , but allowing each supply to cover the current needed for what ever it is connected to i.e 6A for each motor in your case .

in this case current capacity is more important than voltage , as the controller supplying the motor can be current limited by onboard resistors on a per motor basis , and therfore the voltage is also limited to . 

your voltage requirement needs to be as i said before , as a crude  guide 5 times the rating but it's not critical so 24v - 30v will be fine
just keep it below the maximum requirement of your controller by say 5v   

as i said this is a quick crude way of finding power supply ratings, without going into all the mathmatics and formulas , so yes everyone will find their own disagreements
if they wish to look for them , however it works in oractice.

i am just trying to keep it simple for the electronicly challenged amongst the community  .

Dave