1PH supply to a 3ph vsd

[robmwa]

I have a 3phase VSD for a pump, but only have a 230v supply, is it possible to run the pump through the vsd with a single phase supply?

 

[itsmoked]

Certainly as long as your motor is not too large as then it gets very expensive.

You also need a VFD that doesn't care about missing phases. It has to be larger than normal.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[robmwa]

how do i connect this do i connect 1 phase or loop out the three phases with my 1 supply?

 

[toygasm4u]

Yes, like Keith said; anything over about a 5HP motor will become cost prohibitive to do this.

You will want to make sure the VFD is capable of 1PH operation, and you will also be required to roughly double the size of the VFD to accommodate the loss of the third phase. (5HP motor takes a 10HP drive, etc.) I know that for VFDs such as the Allen-Bradley PF40 series, this is commonplace.

One other thing I commonly have to be cautious around when doing this are delta secondaries, be it a 240/120 with a wild B phase or a 480V corner grounded or open delta. VFDs like to see some balance on the inputs; if at all possible make sure you're on a properly grounded wye system when doing this.

 

[robmwa]

Sorry lads, to get this right ( i don't want to make a costly mistake!)

I connect my single phase supply to my R phase on the supply of the VSD and loop out my other 2 phases. Applying the same for the secondary and send the single phase to the motor.

The motor is 4hp.

 

[jraef]

No!
Connect the two line leads of the 1 phase supply to two of the three input terminals. Most VFDs don't care which two, some require that it be L1 and L2. Don't "loop" anything!


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[xnuke]

To clarify, are you saying you want to have a 1-phase input supplying a 3-phase VFD, then use only 1 phase of the VFD output to a single-phase pump?

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[jraef]

D'oh! Missed that...

Xnuke is right, you can't use only 2 phases off of a 3 phase VFD, it will trip on unbalanced output current. Then there is the other big issue of using 1 phase motors on VFDs at all, which can touch off a lengthy debate in this forum.

My "Reader's Digest" version: only a select few types of 1 phase motors can be used with VFDs, and the VFDs are specially designed for that purpose. You don't use 3 phase VFDs for the few types of 1 phase motors that can be operated by them.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376