VFD 240V IN 415V 3 phase out

MisterBill2

Joined Jan 23, 2018
27,504
Whatever is done, the connections in the motor junction box look rather nasty. Good connections are vital for a three phase motor, especially. A high resistance in any phase connection will certainly cause problems, which if the TS is really lucky will only be overload shutdown tripping.
Those terminal posts and connections look like it has been underwater for a while. There is no room for rust in power connections!!!!
 

MisterBill2

Joined Jan 23, 2018
27,504
@jonnydolt
I have just now re-read the title of this thread (or maybe actually read it for the first time) and I wonder if we have been talking about the same thing all along or not.

VFD 240V IN 415V 3 phase out

You do realize that your VFD will NOT step the voltage up to 415V, right? It takes in 240V single phase and outputs 240V 3 phase.

View attachment 295601

For the duration of my participation in this thread I have been talking about a way to power the motor with the 240V 3ph output of thhere is NO NEUTRAL e VFD instead of 415V 3ph that it expects. I wonder if you've been reading it that way, or if you've been reading it some other way because you were expecting 415V would be available at the output of the VFD.

That is why I suggested a new motor. I don't think yours will operate reliably and/or at full speed, with only 240V as its input.
There IS NO NEUTRAL connection to a three phase delta arrangement. At least, unless in the current civilized world.
There SHOULD BE a "safety ground" wire tied to the motor frame, which is not part of the power circuit.
Connecting any of the three motor drive terminals to a neutral will cause damage.
 

strantor

Joined Oct 3, 2010
6,875
There IS NO NEUTRAL connection to a three phase delta arrangement. At least, unless in the current civilized world.
There SHOULD BE a "safety ground" wire tied to the motor frame, which is not part of the power circuit.
Connecting any of the three motor drive terminals to a neutral will cause damage.
Ok...? I don't disagree but I'm puzzled as to why your contribution of this information was delivered in the form of a reply to something I posted as if it were relevant to what I said, and further why you haphazardly injected your "(t)here is NO NEUTRAL" warning into my quoted text as if I was the one who said that.

Screenshot_20230603-175155_Chrome.jpg
 

MisterBill2

Joined Jan 23, 2018
27,504
OK, it seems that making my post as a reply was a goof on my part.
Going back to the beginning, the photo in post #3 certainly looks like the safety ground, yellow and green, is tied to one phase input. In addition, the TS mentions tying in neutral several times. That is not part od a 3-phase delta connection.
Next, depending on the particular VS drive, the output could easily be a higher voltage than the input, even without a transformer. a voltage doubler circuit can do that quite well. And given that 480 delta (or maybe 460 delta, is 277 volts to neutral from each leg, it is entirely possible that the drive can power the motor fairly well, If the motor is wired delta.
 

strantor

Joined Oct 3, 2010
6,875
OK, it seems that making my post as a reply was a goof on my part.
Ah, ok.
Going back to the beginning, the photo in post #3 certainly looks like the safety ground, yellow and green, is tied to one phase input.
It didn't look that way to me but I can't really tell for sure.

In addition, the TS mentions tying in neutral several times. That is not part od a 3-phase delta connection.
TS is powering the the VFD from 240V single phase mains in Australia. It's my understanding that they don't have center-tapped mains like we do. So his single phase would consist of L (not L1 or L2, but just L), and N.

Next, depending on the particular VS drive, the output could easily be a higher voltage than the input, even without a transformer. a voltage doubler circuit can do that quite well.
The drive in question has no doubler. It is rated 220V input and 220V output. Specs shown in post #34.

And given that 480 delta (or maybe 460 delta, is 277 volts to neutral from each leg, it is entirely possible that the drive can power the motor fairly well, If the motor is wired delta.
The motor is rated 415V (Ausie mains 3ph voltage) in Delta. It seems not to be a dual voltage (277/480V, 240/415V, or 220/380V) rated motor. It seems instead to be a 415V rated motor meant to run in delta, with provision for wye wiring provided presumably just for wye/delta starting scheme. If you wanted to run this motor at full power in wye, the math says you'd need 720V to do it.
 
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