Any 480V VFDs that can run on 240V?

I have powered up many VFDs by gradually ramping up the input voltage, I have noticed that the control screen powers up at a voltage level significantly lower than the min rated voltage. Some of the more sophisticated drives have hundreds of paramenters, I would think some manufacturers must allow the low voltage error flag to be disabled or reset.

In principle a 480V vfds could work on 240V at a derated power level, other than the fact that the low voltage error disables the drive. Are there any 480V drives that can set to work on 240V by playing with the parameters?

nope afraid not

the internal parts of a vfd are incapable of boosting the voltage so if you was to put 240v into a 480v vfd you will get a bus volatge of 240 x 1.414=339vdc. the vfd runs the motor by turning this on and off at very high speed so the most the drive could put out would be 339vac under load this would be alot lower.

the question is can you run a 480v motor of a 240v vfd? lol no idea realy

How about the question:

Can one run a 240 V motor from a 480V VFD supplied by 240 V mains?
For the sake of discussion, let's not care if it's single or 3phase input.

Is low voltage a show stopper for the control? Or just a safety for the motors?

Is that a question for you SBEAR? I am curious.

CalG

SBAER said:

I have powered up many VFDs by gradually ramping up the input voltage, I have noticed that the control screen powers up at a voltage level significantly lower than the min rated voltage. Some of the more sophisticated drives have hundreds of paramenters, I would think some manufacturers must allow the low voltage error flag to be disabled or reset.

In principle a 480V vfds could work on 240V at a derated power level, other than the fact that the low voltage error disables the drive. Are there any 480V drives that can set to work on 240V by playing with the parameters?

Click to expand...

Yes there are, but they are usually the most expensive ones. Most VFDs can accept an input voltage as low as -10% of the lowest "Class" nominal voltage. So for instance, what we think of as a 480V VFD is called a "400V Class" with most manufacturers. In that class, they design it to work on older IEC nominal voltages as low as 380V. So the lowest threshold voltage would then be 90% of 380V, or 342V, which is almost -30% of the 480V line. Still not low enough for what you are asking though.

Keep in mind however, that the output voltage is never higher than the input voltage, so if you only give it 240V, it will only run a 240V motor, not a 480V motor. It can't create voltage from thin air.

But there are a few; Telemecanique's ATV71 is one that comes to mind, where the lower input voltage limit is 50% of the nominal voltage class (not 50% of the lower limit as mentioned above). So the 400V class drive can accept 200V input. That would work for you. But that is one of the most expensive drives on the market, and the price will be based on the current rating at 480V, not 240V, so you will pay a lot extra to boot.

About the only time it does make sense is when you have a piece of portable equipment and you want to allow it to accept any input voltage. What you would do then is use a 208V rated motor, then program the drive to provide 208V output at full speed, regardless of what the input voltage is. One potential issue is however, that when you are running a 240V or 208V motor when the VFD is powered by 480V input, the VFD must "squeeze" more pulses into the PWM pattern to make the the 620VDC pulses only end up at 240VAC RMS. That also means that the motor insulatiuon is going to see the same kinds of stresses as a 480V motor would. So if your motor was designed on-the-cheap because it was never expected to be used on something like a 480V VFD, then it will likely fail quickly.

Drives Direct....(drivescirect dot co dot uk) has one that they advertise as 240V,1ph input to 415V,3ph output.

I've also noticed those on the eBay UK website. Sort of pricey, but probably less than the cost of a 240/480 transformer.

http://stores.ebay.co.uk/Drives-Dir...ERTERS_W0QQcolZ4QQdirZ1QQfsubZ5QQftidZ2QQtZkm

CalG said:

How about the question:

Can one run a 240 V motor from a 480V VFD supplied by 240 V mains?
For the sake of discussion, let's not care if it's single or 3phase input.

Is low voltage a show stopper for the control? Or just a safety for the motors?

Is that a question for you SBEAR? I am curious.

CalG

Click to expand...

The reason I am interested is that I come across big used 480V drives all the time, but in Canada there isn't much of a market for them. If I could use them to run 208/230V motors with a 240 single phase input they would have some value to me. I am not surprised that this is possible on the more expensive drives.

precisionworks said:

I've also noticed those on the eBay UK website. Sort of pricey, but probably less than the cost of a 240/480 transformer.

http://stores.ebay.co.uk/Drives-Dir...ERTERS_W0QQcolZ4QQdirZ1QQfsubZ5QQftidZ2QQtZkm

Click to expand...

Interesting link, the drives that are marked as Teco look a lot like Yaskawa drives to me.

Jraef said:

But there are a few; Telemecanique's ATV71 is one that comes to mind, where the lower input voltage limit is 50% of the nominal voltage class (not 50% of the lower limit as mentioned above). So the 400V class drive can accept 200V input. That would work for you. But that is one of the most expensive drives on the market, and the price will be based on the current rating at 480V, not 240V, so you will pay a lot extra to boot.

Click to expand...

Thanks that is useful information to me. Are there other drives, ABB maybe they are expensive and I trip over them all the time.

I come across big used 480V drives all the time

Click to expand...

Not a big market in the USA either, especially in small commercial shops. Most bring in a 240v, 3 phase service & think that's good enough, not realizing how much used 480v equipment is available. Then they pick up something at auction or on eBay & find out the cost of a transformer to make their 'cheap' equipment usable

-------------------
Barry Milton

Sbaer

If you trip over a good one that doesn't break your leg, (or the bank)
I would be willing to "play" with it. Just to check out the possibilities.

CalG

MY 480v VFDs run on 240v...

SBAER-

As Barry suggested- a transformer can make a 480v drive run on 240v... ALL my 480v drives run on 240v SINGLE PHASE... I use a dry transformer, wire the primary (480v) side to the input of my drive, and the secondary to the 240v mains (through disconnects and contactors, for safety and control, of course).

As others noted, 480v drives are cheap and plentiful, and dry transformers in commonly-needed sizes aren't hard to find, either. I bought a few Allen-Bradley 1336S VFDs in the 5-10hp range for $35 each, and found transformers in the 3-10kva range for about the same... thus putting a 480v three-phase machine on 240 single (with variable speed!) for about $100 each... the balance being wiring, control potentiometers, pushbutton switches, etc.

MY 480v VFDs run on 240v...

SBAER-

As Barry suggested- a transformer can make a 480v drive run on 240v... ALL my 480v drives run on 240v SINGLE PHASE... I use a dry transformer, wire the primary (480v) side to the input of my drive, and the secondary to the 240v mains (through disconnects and contactors, for safety and control, of course).

As others noted, 480v drives are cheap and plentiful, and dry transformers in commonly-needed sizes aren't hard to find, either. I bought a few Allen-Bradley 1336S VFDs in the 5-10hp range for $35 each, and found transformers in the 3-10kva range for about the same... thus putting a 480v three-phase machine on 240 single (with variable speed!) for about $100 each... the balance being wiring, control potentiometers, pushbutton switches, etc.

Well, Cheep is right.

Ebay just offered up a 480 V unit for 10 bucks. Shipping is more.

I suppose a transformer will be next ;-)

CalG

Is the Allen-Bradley 1336S VFD an older model? I took a look at A-B's website and did not find it. I've got my 380V Schaublin running of a 240V RPC and it's internal transformer. But changing belts really is a pain (even the flat belt can be troublesome changing pulleys), so I really miss variable speed.

One twist that my application would present: I have a two speed motor (900/3600 rpm @60Hz, 0.8/2.0 HP). If I wire it up RPC->X-former->VFD->Motor(Spd. 2), will I get reduced torque at lower rpm?

In other words: 900 rpm 0.8 HP motor at 60 Hz = 900 rpm, 4.7 lb/ft torque
3600 rpm 2.0 HP motor at 15 Hz = 900 rpm ? lb/ft torque

BTW, the motor is nameplate rated to run at 670 rpm @ 50Hz, so that would give 6.3 lb/ft torque if I have the math right. I remember reading here that electric motors operate in constant horsepower mode above the nameplate rpm.

The mechanical brake on the Schaublin works quite well, brakes and disconnects the clutch, but the motor keeps spinning too (freewheeling) and when you take your foot off the brake pedal, the clutch re-engages and the spindle keeps spinning slightly. So a brake resistor would also help in that both braking actions could happen at once (disconnect motor and brake spindle while motor is electronically braked with zero load). This would enable very fast stops.

I stop a lot to take measurements, so anything that speeds that up is nice.

1336

the allen bradley 1336 is the old model of the powerflex. allen bradley tryed too stop making the 1336 but there was a revolt amoung the industrial comunity who had come to love and respect the drives. so even today you can order new 1336 they just cost more as they have to be assembled. the powerflex is a better drive but its a pain to program when you are using network controls. this was caused when someone decied to change the word number for the controls and forgot to tell the sale staff so what should have been plug and play now required programming. in industry alot of people dont use start/stop wiring but instead connect the drive to the network so you have more control of the drive.

my favorite is the abb 550 and in 480v its a cheap drive of ebay

SBAER

In respose to your original post, My reading discovers that Toshiba E3 series VFD's allow the "LOW VOLTAGE" warning to be defeated by programable settings.

I'm not sure of the ramifications however.

CalG

1336...

The 1336 came in several different flavors, and many different form-factors to suit motor sizes. From what I can tell, the "S" indicates Sensorless Vector operation, while the F... I'm not certain. My guess is that it operates in V/Hz mode, but not sure. There's a few other 1336 types, and as Skirty said- they were very popular in industry. The marketing beagles had a field day coming up with 'catchy' names that don't really identify the product, and I don't think they really had a clue what signified what... they just "added value" of confusion to an otherwise simple and sensible product series.

There are SOME larger versions of the 1336 that have a DC BUS input, so if you'd like to build your own single-phase rectifier circuit, you can bypass (and avoid the limitation) of not running three-phase input. Better be a good electrical engineer if you do, as you'll want to set it up with ballast resistance for soft-start, and a bypass contactor once the capacitor banks have charged up... and include proper fusing for protection (both you, and the VFD, and the machine).

Well, The test has been made, and an answer given on one VFD that just happens to be on my test bench.

YES! Well ....sort of.

Here is the story. Based on this original post question, I picked up a 440 V VFD at a comfortable price. The unit requires 3ph input and mentions consulting the factory if single phase input operation is to be considered

Since I don't have 440 V 3ph service in my shop, some alternate sources of supply were evaluated.

First, Direct 240V single phase to L1 ,L2 or any combination with L3 got the display to light up, But a reset, display change, or data change was not to be.

Second go: the output of the home built 240 V RPC was clipped into L1,L2, L3. Bingo! The display lit up, and data could be modified. (LOTS of options) But, Though at times it appeared that the unit was on the verge of useful operation, It only took a finger waving at the frequency increase key and the under voltage warning would take it's place on the display. Clearing the fault would get back to the "near working" state, but when the low voltage detection time expired (set to 10 sec.) the fault warning returned. The undervoltage trip had been disabled previously. I thought there might be a chance that the unit would go operational in spite of the fault message, but that was not to be. The fault message must have been cleared 500 times in hope ;-)

Some feelers were put out to try and snag a step up transformer, and I even made a trip to the local shop where I new there was 440 V service. No luck on the transformer locally, and a hand written sign on the shop door told me that this was the afternoon when "something came up. No Go.

Well a brainstorm will raise a lot of dust. With a sleepless night "figuring the angles" I thought to put a ganged Variac that is in the shop inventory to the task. Perhaps a little voltage boost would be enough. Variacs allow about 25% boost over line voltage.

And.... Yes! With two legs of the RPC runing through the Variac and boosted to 290 Volts and the third leg at about 270 to either of the other two, the drive smiled its 00 frequency and made a soothing fan sound suggesting all was well.

I clipped in the little Italian .27 kw 220/380 volt motor that is kept on the window sill just because it looks so cute. and Viola! As the Freq. increased, the motor shaft began turning! (The motor profile in the drive had been setup just for this little guy)

After what seemed like way too long acceleration, (A review of the parameters discovered the default acceleration was set at 60 seconds) the little motor was spinning it's heart out on the bench and I could see that the drive was not going to let up until some real speed was had. I pressed the stop button at about 80 hertz

I played around this way for about a half hour, and then what do you suppose? The low input voltage warning showed up (well, actually, I moved the dial on the Variac, and that dropped the in line voltage just that much. It must have all been right on the ragged edge of operation. It was time to call it a day. so I just packed all the clip leads away for a fresh go another time.

In recap

Some 440 V 3ph VFDs will function at about 290V 3ph input.
Not in any useful way however ;-)

Perhaps all would be fine at 330 V.

A bank of 3 buck-or-boost transformers might be a next step. It would be fun to find out what minimum single phase voltage is needed to power up the DC bus.

A day in the shop!

CalG

Cal, is there a parameter to ignore input phase loss?

That's what my altivar 58 needs done or it will fault on start up without all three legs present.