multiple motors run on one VFD?

It should be OK, provided the VFD doesn't try to regulate the RPM in any way, such as by reading a back voltage.

As long as you don't switch the leads between the VFD and the motors while the drive output is on, you're OK.

Ned Simmons

A varition of this question...

My packing line is run with an home made 3 phase converter. There are seven

Karl

Thanks guys... one other question.

Forgetting about running two motors off one VFD for a second here...

Is there a really stripped down version of a VFD that I could find (read CHEAP!) or a package that combines a 3 phase motor, (anything above 1/4 HP) with just a dial to control the RPM... all of the VFD's I have bought are "somewhat" complex and have alot of options, LCD screen, etc... but I have always required a 3HP or larger VFD.

Just wondered if someone knew of a package that has a real small motor like what I need. I know EBAY comes up with all kinds of one-off deals, but I would like to find a supplier that I can keep getting these from if all my buddies want one of these tubs! ;-).

thanks, ron

I have a lot of VFDs for sale, up to 25 HP, but they all require some setup. Eventually once you set them up, you can run them with a small switch (that controls the VFD's output) and a potentiometer.

When I built a vib tumbler, I used a tread mill motor. They're DC and have their own speed controller. I got mine at the dump (there's a couple there every month). I know you didn't ask the question that I'm answering, but the tread mill motor is a good alternative. I posted my vibe'r to the DropBox:

I realize this is true for many VFD's, but it turns out you don't need to worry about it with Danfoss drives, at least the 2800 and 5000 series. They're rated for being used with manual disconnects. Before I bought mine I verified my understanding with one of their apps engineers. I've got a 7.5HP Danfoss drive mounted to the wall that runs all the three phase tools in my shop, manual switches, just like they were plugged in to the real thing.

Steve

Steve,

That is a great tip!

I also learned today that you can buy smaller HP rated VFD's that take

Bob, Nice Vib Tub! Mine is a U shaped tub, quite large, different approach because I have bigger parts to tumble. ron

That's very cool. Thanks for the info.

That's very good to know. I may be able to take advantage of that feature on some equipment I quoted recently.

Ned Simmons

There are probably other brands with the same feature, but I don't know which they are.

Note: Danfoss drives aren't cheap new. My 7.5HP unit runs about $1500 new....but I bought it on ebay.

Steve

No packages that I know off..but VFDs are now prettty damned cheap in low hp

Gunner

Rule #35 "That which does not kill you, has made a huge tactical error"

Not knowing the staring currents, it is hard to tell. If you can start the biggest first, the smallest last then that would help.

Wes S

Having given this a few more seconds of though, I would think as long as the VFD was sized for the combined HP of your motors you would be good to go. With the sequencing, you might even get away with a smaller than recommended unit since startup inrush will be lower than one big motor.

Wes S