VFD driving

[grifftech]

Can I drive a VFD off mains. 60hz, 120v

[rs20]

Some VFDs yes, other VFDs no. You'd best provide a specific VFD model. In general, typically, I think the answer is "yes".

Lol. like briselec below, I thought OP meant Variable Frequency Drive as well (just like Google).

A vacuum fluorescent display? A specific VFD requires a certain amount of DC filament voltage, about 60V DC from memory? It might be interesting to somehow rectify and chop down mains electricity to get your 60V DC, but if you did that in the naive way you'd end up with the 60V DC with respect to mains neutral, instead of mains earth. This is very dangerous. You need to use an isolated transformer for safety.

Given that you need 5V or so for whatever circuitry drives the VFD, I'd probably suggest that you just step up 5V (or 12V, or whatever else you have handy) up to the 60V DC. It'll be less complex than creating a safe supply from mains.

Do you have a particular design in mind for how you're going to convert 120V AC to ~60V DC? How are you going to power the microcontroller (or whatever) that will be driving the VFD?

[briselec]

If you mean drive a 3 phase motor with a vfd connected to single phase, yes but only with a vfd that has that capablity.

[grifftech]

Vacuum fluorescent display.

[danjenkins]

VFD choices are limited at 120V. AC Tech has few of them. If you can move up to 208/240V you'd have many more choices.

Here's one of them that can run in 120V http://shop.actechdrives.com/AC-Tech-Lenze-SF110S-p/sf110s.htm

[Falcon69]

If you mean drive a 3 phase motor with a vfd connected to single phase, yes but only with a vfd that has that capablity.

and then you will want to get a VFD rated for twice the HP rating of your motor.

For example. You have a 4.5kW (~5hp equivalent) spindle motor for your CNC. But you only have 220 or 120 (not recommend to run on 120) and not 3-ph.  You will want to buy a VFD with a HP rating of 10HP.  You might get away with a 7500HP if it is a Hitachi or other good named and reliable brand. Those Chinese ones won't do it. They are junk.

EDIT:
Found It!

http://www.hitachi-america.us/supportingdocs/forbus/inverters/Support/AN032404-1_Rev_A_Sizing_for_Single-Phase.pdf

[matseng]

No...  The filament of an average VFD wants about 3-4 volt AC, then a voltage between 15 and 60 volts DC to light up the segments. This depends on if the display is dynamic/multiplexed or static/direct drive.

[dannyf]

"Can I drive a VFD off mains. 60hz, 120v"

I have a thankless well water system where the vfd pump is always on. I don't recall the wiring but it doesn't seem to be that powerful so I suspect that it is a single phase vfd motor.

My pump is in the well but friends have those always on online vfd pumps that seem to be too small to be 3phase motors.

Newer ac systems use vfd compressors and they are definitely single phase.

[danjenkins]

If you want to replace your pump motor, take a look at Leeson. I have one of their platinum series motors and have been very happy.

http://www.clrwtr.com/PDF/LEESON/LEESON-Permanent-Magnet-AC-Motors.pdf