Kuka robot project - hardware choice

tommylight wrote:

In Europe you can get toroidal transformes for any secondary voltage, that is the easy part, the 5.4A rating is most probably the long term current the motor can withstand, peak current will be much higher so the drives are usually 20A or 30A rated, hence the power supply must be rated accordingly, in your case at a guess at least 60A transformer and rectifier. Or have 2 of the big motors on one power supply and 4 smaller on another power supply, at 30A to 40A each are easier to manage and find and might even be cheaper. You might easily make do with much less as it is a small weight, and use moderate accelerations.
Does the control box have power info on it? Should be in KW,
 

Yes, two toroid supplies might be the best solution.  Note that these transformers can be overloaded for short intervals, and that the PWM servo amps are switching power supplies, so that power input is just a little over power out, so they can deliver large output currents when the motor is moving slowly, while drawing MUCH smaller current from the DC supply.
Jon

greg23_78 wrote:

i don't have the electrical cabinet with the robot
i'd like to start with a second-hand 400 to 240V high-power three-phase autotransformer because it's “quite easy to find”. i'd like to share the phases and neutral to supply the drivers with 110V single-phase power.
i have 3xbig motor and 3xsmall motor so 1 phase for 1 big and 1 small.
after some research i managed to find some data on robot or control electrical power.
robot KR16(more recent than my robot but quite similar) = Installed motor capacity 8.8 KW
cabinet : Rated power input depending on the drive class: 7.3 -- 13.5 kVA.
I don't know which transformer power I should look for 12 KVA minimum? 400V/18.1A - 230V/31.4A

assuming that large motors will be at a maximum of 50%-60% of their maxspeed (110V instead of 180V)

KR16 powerKW
 

Attachment not found

KRC2 power KW
 

Attachment not found

 

Note that with Pico Systems servo amps, the supply MUST be isolated from the mains, an autotransformer must not be used.  This is because there is no isolation barrier between the control logic and the main transistors to keep cost down.
Jon

a pity about auto transformers, because there are plenty of them for sale, and they're high-powered.

I'll turn to this:



is it insulated?



moreover, i found in my garage two insulated 400/240 - 110V transformers with a power of 1000VA with two 110V 2x4.26A outputs and can up to 5000VA for short time

 

so I'll go with

transformer 1000 VA : - motor 0.57 kw 1.6A 143V
                                - motor 0.57 KW 1.6A 143V

 transformer 1000 VA: -motor 0.57 KW 1.6A 143V
                                -motor 1.5 KW 3.7A 146V

transformer 3000 VA :- motor 2.5KW 5.4A 185V
                                -motor 2.5KW 5.4A 185V

does this sound right or is the 3KVA transformer too small?

 

is it possible to drive kuka drivers or not, they are completely blocked by kuka?

 

Vevor no, but maybe, usually not isolated.
The 1000VA looks good, has outputs that can be paralleled giving 8.7A and can handle quite some beating, so get 1 of those, it will be more than enough for testing and running individual motors. After you do that, you can try using 2 or more motors with it and see how it behaves, you might just get away with 2 or 3 of those if no fast acceleration is needed.
Kuka does not makes drives, Siemens does/did, although that looks like something Beckhoff would make, so try finding more info on them. Also notice Kuka used fieldbus and profibus for comms...