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  • read the controller nameplate. label is on the outside of the cabinet, close to door hinge. there is also backup label inside the cabinet.

    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

  • There's also the voltages to consider. KRCs run on... 400VAC, internally, if I recall correctly, but the KRCs usually ship from KUKA with an external transformer that is set for the common supply voltage at the destination.

    For North American robots, the transformer input voltage is usually 480VAC 3-phase, although I think some Canadian facilities run on 575VAC. I think Japanese mains run 440VAC, usually.

    So, as Panic says, the specifications should be on the data plates on the KRC, but you'll want to check for both the controller spec and the transformer spec.

  • Most of the world used 400VAC for three phase system. that is what KRC4 is designed for. but there are exceptions and that is why three are transformer options.

    for North American market, controllers are KRC4-NA and come with transformer, have no X1 connector since power is supplied through strain relief on top of the cabinet and disconnect switch is NA style (interlocked with the cabinet door).

    this transformer version has three taps: 440V, 480V and 575V.

    440V is used in parts of Brazil (not exactly north but probably added to reduce number of configuration options).

    480V is used mostly in USA and occasionally in Canada. standard in Canada is 575V though often it is referred to as "600V".

    on controllers with transformer, secondary is always 400VAC so that same MADA is used like in the rest of the world.

    but even without transformer KRC4 can operate on other voltages such as 380V, 440V or 480V - as long as:

    1. supply is referenced to ground

    2. phases are symmetrical with respect to ground (some places in USA use corner grounded delta, hence need for transformer).

    3. robot in WoV project is replaced with same one but from AFC catalog that is meant for different supply voltage. so if trying to run transformerless KRC4 meant for European or Asian market in USA for example, as long as supply is fine (points 1 and 2), all one need to do is delete robot from WoV project, insert same robot again but from 480V catalog, you are good.

    if you don't change MADA (pick robot from correct catalog), parameters used for KPP will be wrong. When powering up, everything will look fine but there is a good chance that drives will blow up when you press enabling switch. if that happens KPP and all KSPs will be smoked. Reason is that in order to support higher input voltages such as 440V or 480V, KPP overvoltage limit is increased and hence not sensitive to act as expected. i have seen few that did not blow up right away when drives are enabled but this is thin ice so use at own risk.

    btw, since i am in Canada, i always power up transformer only to check secondary voltage. in quite few placed 575V is too high, for example 626-640V.

    this means that secondary voltage can go quite above nominal (436-445V) which exceeds required 400V +/-10%.

    i don;t see KRC4 complaining but that means any margin for line transients is gone. good luck when grid is unstable like in bad weather.

    i have contacted utility company to make them aware of the issue and they would change taps on a big transformer that provides power for entire plant. they like to leave it a bit higher but some 585V is within 2% of expected 575V, compared to 628V it used to be (over 9%).

    but the topic started with question about current. without mention of used voltage or in which part of the world this is installed.

    so.... the best answer is read the nameplate.

    some clients have argued that listed 25A FLA is too large for their existing power drops and disconnects (many use 15A or 20A).

    well... talk to your field inspector.... that raring is generous since KRC4 can be fitted with more drives. KRC4 standard can do up to 9 axes (6x 64A + 3x20A).

    KRC4NA uses transformer, either 8kVA or 13kVA. generally KR60 and smaller will get 8kVA transformer in the controller. but 13kVA is used for everything above that.

    transformers can convenient bottleneck since if loaded, core saturates and limits how much power can be transferred.

    doing a little math using 3-phase power can get you what the current limit is at some voltage. again, read label, do the math and talk to your field inspector.

    but it is also possible to use it without transformer

    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

  • Thanks Guys.

    Now i have alot f question to make to the electricity guy and my robot supplier. I will be back to you as soon i do the configuration of electric setup and i will post my experience.

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