Use 3phase input VFD on single phase?
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    Default Use 3phase input VFD on single phase?

    As the topic says, i have received a 3phase input inverter with a mill recently aquired. Can a ABB 3 phase input inverter be used by just giving it single phase input? I have single phase in my workshop and convert to 3phase with a RPC. If i can run the mill without the RPC (use 1phase line in and 3phase out) it would help immensely

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    Find ABB model number

    if (unable to find manual on internet)
    then ask question

    if (unable to find answer in manual)
    then ask question

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    Already have the model nr and manual, unable to find the answer there, could you perhaps help?

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    Quote Originally Posted by Rhynardt View Post
    Already have the model nr and manual, unable to find the answer there, could you perhaps help?
    Derate Three Phase VFD for Single Phase Power

    dee
    ;-D

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    Thanks dcsipo, thats the exact answer i was looking for.

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    Quote Originally Posted by Rhynardt View Post
    Already have the model nr and manual, unable to find the answer there, could you perhaps help?
    The derate factor is something I didn't want to mention until I looked at the documentation.

    What is the model name/number of the drive? You never know, someone might have the same model.

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    I recently called ABB with this exact question since the manual did not address it clearly (at least to me). Was momentarily disappointed in that the person answering the phone required me to give info in order to start an internal "trouble ticket". But within a minute they had me talking directly to an engineer who answered that question definitively as well as several other quick programming questions.

    And yes, my 7 1/2 hp 480V VFD operates fine on single phase input, though derated.

    Jim

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    Quote Originally Posted by Jim S. View Post
    And yes, my 7 1/2 hp 480V VFD operates fine on single phase input, though derated.
    Is your single phase 240V? 240V single phase into a 480V 3 phase VFD? I know very little about this. I never would have guessed that was an option.

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    Quote Originally Posted by ptsmith View Post
    Is your single phase 240V? 240V single phase into a 480V 3 phase VFD? I know very little about this. I never would have guessed that was an option.
    Step up transformer can be used to go from 240 to 480 prior to the VFD. There are a few VFDs sold in the UK that will step up 240 to 480VAC.

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    Quote Originally Posted by ptsmith View Post
    Is your single phase 240V? 240V single phase into a 480V 3 phase VFD? I know very little about this. I never would have guessed that was an option.
    480V single phase input. With derating, ABB engineer said that I could expect to get 3 1/2 - 4 hp from my 7 1/2 hp VFD. I simply used a step-up xformer to boost 240 single to 480V single phase as mksj points out above.
    Jim
    Jim

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    All my VFDs (to include Allen_Bradley 1305 and 1336, and 1336F, an Omron, and a Minarik, all get single-phase, and work just fine that way. The bigger machines have motors wired for 480.. Hasn't hurt a bit since.

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    Technically, ALL VFDs can operate from single phase power. A VFD just converts AC to DC, then recreates something that motors react to as if it is AC again ("pseudo AC").

    Where you get into trouble with this is in the rectification process. With a single phase input, only 4 of the 6 diodes on the diode bridge rectifier are going to carry ALL of the current, with means that the current through the diodes increases by the square root of 3, 1.732x. But in ADDITION to that problem, your DC bus capacitors have to work a LOT harder to smooth out the "ripple" in the DC bus from the rectifier. In a 3 phase input, the DC bus never gets to a zero voltage state, so the capacitors don't work all that hard and run cool. But when you have a single phase input, the ripple will drop all the way to zero V 120 times per second, so the caps must work harder and they will get hotter. That is really what the de-rate factor is all about, and depending on the VFD design, that de-rate factor can be anywhere from 50% to 65% (meaning the maximum motor size is 35% of the VFD rating if run from single phase), typically depending on whether or not the VFD has a DC bus choke or not. Most VFDs built to US or EU standards will have DC bus chokes, most Asian drives will not and require more de-rating (or a de-rating of the temperature to 25C/77F operation).

    But also for this reason, SOME of the VFD mfrs will put in a "Phase Loss" detection and protection circuit that simply looks for the loss of any phase and shuts the drive down so that the DC bus caps are not damaged. Then SOME of those mfrs, for some reason, do NOT allow you to disable that Phase Loss Trip function. Those are the only VFDs that cannot operate from single phase, but only because the mfr is not ALLOWING you to do that. If you are not sure, look at the instruction manual and if they HAVE a Phase Loss trip function, look then to see what it means* and / or if it can be defeated in programming. This inability to defeat it however means that people like you, meaning people with only single phase sources and 3 phase machines, are lost to them as a market potential. For that reason, this issue has been going away as more and more drive mfrs catch on.

    *One WAY of detecting whether or not you have a phase loss is to monitor the DC bus ripple, since that's really the only issue. So for example all A-B drives do this, meaning they don't actually look to see if there is voltage on each line terminal, they only loom at the EFFECT of a phase loss. So if the motor is lightly loaded, OR the VFD is over sized, the VFD does not have excess DC bus ripple and hums right along. So on A-B and ABB drives there is no way to defeat the Phase Loss trip function, but by reading the description of HOW it detects a phase loss (excess DC bus ripple), you can understand that by de-rating the drive, it will be fine.

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