Powering a KR C4 Compact Controller

    Hello all,
    I just received 2 brand new KR C4 compact robot controllers. They very clearly state 200-230VAC. I have 480VAC supply in my building and a 208VAC Wye transformer ready to go. When I triple checked with Kuka regarding the 208 wye, they told me it would not work, and I needed 230v single phase or 230v two-phase at a phase angle of 180 degrees. I have looked through their wiring schematics (in German...) and nothing looks like it would be damaged... But I do not know German and do not have the bill of material. The manual says:


    "200 V - 230 V AC, single-phase, two-phase (with grounded neutral (as symmetrical as possible) between the phases used) 50 Hz ± 1 Hz or 60 Hz ± 1 Hz"


    I took this to mean if I have two-phases they should be symmetrical about ground/neutral with regard to voltage. A 208VAC wye is symmetric about ground (120V each at 120 degree phase shift).


    Has anyone run these controllers on 208VAC wye? What could possibly require 180 degree phase angle?


    Thanks!

    I'm not experienced with the Compact, but I believe it is built to run off of household wall-socket current (I could be confusing it with the LBR/iiWA, however). That would suggest that it requires single-phase 220VAC (give or take a few volts) between the neutral and the hot. In typical US household electrical systems, the incoming service is two opposing phases of 120VAC relative to a center neutral. As such, small-appliance 120VAC can be tapped between either phase and the neutral, while 220VAC for large appliances can be tapped across the two opposing phases. My guess is that the Compact is intended to run off such a "large appliance" supply.

    Thank you SkyeFire. You are correct in what you said. I ended up just buying the transformers to get a 180 degree phase angle. Still no real idea why this is necessary. Apparently the controllers will actually burn out on wye configuration power.

    Power drawn from two legs of a Wye (or Delta) 3-phase circuit will be two sine waves only 120deg out of phase. Some motors will limp along on this, but for a system like the robot, this will look like a badly voltage-oscillating power supply.

    i have seen single phase controllers KRC4 compact and KRC4 small size (version1) run just fine from two leg of the three phase 208V supply.


    there is also new KRC4 small size (version2) but this one is powered from three phase just like KRC4 standard (380-480VAC 3P).

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

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