Transformer for Allen Bradley VFD

I have a bridgeport 2J with a 1.5hp motor. I bought an Allen Bradley 3hp 3ph online for a good price before realizing it's set up for 380-480V input. I can power it up with 240V, but just get a "not enabled 0.0 Hz" message. I'm thinking the root cause is the input voltage since that's definitely out of spec. The motor is 2.2A at 460V, so that's ~1kW. Since I'm feeding the VFD with 2 phase, I should increase it by 33%, so I need ~1.33kW going in. Is a 2kVA transformer going to do the job for me to step up the input from 240 to 480?

thanks

Specify your VFD FULL catalog part number. It appears that you will need a transformer.

It's a 1336S-BRF30-AN-EN

your vfd is barely large enough you may be able to get away with reconnecting the input rectifier for voltage doubling and run it on 240v. don't overload your machine long enough to warm up the capacitors. i wouldn't bother trying to program current limits into the vfd but either buy a 10$ watt meter on ebay and wire it up to the input and keep it below 1kw, or just baby the machine rather than letting the 1hp motor bog down (a good motor bogs down at nearly twice the nameplate hp)

lxrubin said:

It's a 1336S-BRF30-AN-EN

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Look on the data plates for the specific build date, post that here.

IF.. you knew enough about electronics to re-connect as a Voltage Doubler? Probably would not have purchased the wrong VFD for the job to begin with, yah?

Smarter move than a transformer may be to go and get a brand-new VFD of the correct specs, already single-phase rated by its maker. Who wants to be married to a shop-modified orphan, anyway?

Small motor you have, decent new ones are not terribly costly, you'll have the full, brand-new, Warranty coverage, and low/no need to play research lab.

Thanks. I'm guessing you're suggesting that after I step up the input voltage, right? I'm not familiar with voltage doubling via input rectifiers.

Why is the VFD too small if it has double the capacity though? I know that since I'm using 2 phase in, that it's losing 2/3 capacity but it should still be good..?

And why not program a max amp into the VFD? Also, I can check the temp of the unit, so maybe there's a max temp limit I could set, but haven't seen that in the manual yet.

Regardless, I'm not planning on doing any heavy work.

thermite said:

Look on the data plates for the specific build date, post that here.

IF.. you knew enough about electronics to re-connect as a Voltage Doubler? Probably would not have purchased the wrong VFD for the job to begin with, yah?

Smarter move than a transformer may be to go and get a brand-new VFD of the correct specs, already single-phase rated by its maker. Who wants to be married to a shop-modified orphan, anyway?

Small motor you have, decent new ones are not terribly costly, you'll have the full, brand-new, Warranty coverage, and low/no need to play research lab.

Click to expand...

yep thanks for the advice. I'll check for the build date in the morning

lxrubin said:

Thanks. I'm guessing you're suggesting that after I step up the input voltage, right? I'm not familiar with voltage doubling via input rectifiers.

Why is the VFD too small if it has double the capacity though? I know that since I'm using 2 phase in, that it's losing 2/3 capacity but it should still be good..?

And why not program a max amp into the VFD? Also, I can check the temp of the unit, so maybe there's a max temp limit I could set, but haven't seen that in the manual yet.

Regardless, I'm not planning on doing any heavy work.

Click to expand...

to configure the vfd for voltage doubling you connect one line to the midpoint of the 400volt capacitors, the other line(s) to the rectifier. by doing so you substantially increase the rms current flowing through the capacitors. this is one of the reasons why when you run a vfd on single phase you have to derate the drive 50%. configuring it for voltage doubling and running it on single phase is an additional derateing, on the order of a third, which is why i suggested this could work since you have a 1hp motor and a 3 hp vfd.

The problem with using motor current limits as a means of limiting the hp is that the vfd is still fully capable of delivering full motor torque at lower speeds because the vfd input rectifier/capacitors are limited by current flowing into the vfd (which is constant power, say 1000 watts), not current into the motor.

lxrubin said:

Is a 2kVA transformer going to do the job for me to step up the input from 240 to 480?

thanks

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See if this manual is correct:
https://www.platt.com/CutSheets/Allen-Bradley/1336F-B075-AA-EN-L6.pdf

For 3 phase input (380-480V)
BRF30: Input kVA = 4.2-5.1 Input Amps = 6.4 Output kVA = 4.2 Output Amps = 5.3.

In one of my AB 240VAC manuals it states:
------------------------------------------------------------------------
The drive is typically used with a three phase input supply. The drive has been listed by U.L to operate on single-phase input power with the following requirement:

Output current is derated by 50% of the three-phase ratings identified in tables.
-------------------------------------------------------------------------

There is no such statement in the 1336 manual below probably due to the nature of the beast. Three phase connections for industrial type drive.

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1336f-um002_-en-p.pdf

Single Phase:
Load KVA = Load Voltage * Full Load Amps / 1000

Three Phase:
Load KVA = Load Voltage * Full Load Amps * 1.73 / 1000

lxrubin said:

..since I'm using 2 phase in, that it's losing 2/3 capacity but it should still be good..?

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It doesn't so much "lose" capacity as ask its capacitor bank to operate with fewer incoming sine-waves. They have to cover the gap, work harder with the greater excursions, cannot do a perfect job, which can then make the rectifiers work harder as well. Thermal stress is involved, too.

VFD built and rated for 1-P input have upsized components to survive that longer. Many STILL DO have higher ratings if/as/when they can be operated on 3-P input. Think up-rated rather than de-rated, if you will.

Voltage doubling, tripling, more-yet is a OLD old trick. Primary use was TV and Oscilloscope CRT HV sources. Lots of volts, but very, very low current, so it made good economic sense.

Also has its downsides and some basic requirements I'd not be comfortable testing the limits of with stock VFD caps not selected for that by the OEM. JST may be comfortable with that, I'd expect jraef to be as conservative as I am.

B'rer johansen may be more daring, of course. Rons might want a 20-year-old Allen-Bradley rather than a 20 day old Hitachi. He isn't always consistent as to which, but your build-date may matter, and matter greatly.



I know the "how" of VFD well-enough. I don't wish to re-invent them. I simply want to treat them as a commodity with not a lot more work on my part than cabling-up a new TV + Blue-Ray, setting time-of-day on a microwave oven, or operating temperatures on a new 'fridge/freezer.

"Appliance" IOW, not an experimental Ham cell-relay, satellite, and landline RWI project nor an air-independent submarine propulsion system.

They just are not worth any special messing with their makers have not already done for their modest, mass-produced prices. Too busy. Got other fish to electrocute.

I can't find the build date anywhere, but it's definitely not new. Likely 10+ years old. I was under the impression that a high quality used unit would be a better choice than a new low quality unit.

Based on ron's calculation, a 2kVA transformer should do it, but I'll likely look at a new VFD that meets my exact requirements anyways.

lxrubin said:

I can't find the build date anywhere, but it's definitely not new. Likely 10+ years old. I was under the impression that a high quality used unit would be a better choice than a new low quality unit.

Based on ron's calculation, a 2kVA transformer should do it, but I'll likely look at a new VFD that meets my exact requirements anyways.

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Your impression is right. It's not the build date that matters as much as the hours if you want to think in those terms. With a import POS the self destruct is designed in with tolerances as slim as a piece of paper. (not the mechanical type of tolerance)

Nothing was calculated. Just provided the drive data and two equations. How did you use the data?

rons said:

Nothing was calculated. Just provided the drive data and two equations. How did you use the data?

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Three Phase:
Load KVA = Load Voltage * Full Load Amps * 1.73 / 1000
1.75kVA = 460V*2.2A*1.73/1000

lxrubin said:

I can't find the build date anywhere, but it's definitely not new. Likely 10+ years old. I was under the impression that a high quality used unit would be a better choice than a new low quality unit.

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Unsupportable, in the general case. That is very rarely true for electronic devices of any kind.

A "low quality" VFD that meets the same performance specs looks much the same as an expensive one from the viewpoint of an Electron. Not a reason to buy junk just because it is new. But old formerly-great are more "old" and "formerly" than they are still "great".

In any case, technology has moved on, components have aged, the unit has been worked under stress. At the minimum, a ten-year-old unit should have new capacitors.

I liken buying used VFD to buying used tires.

Welll. maybe not as good.

Some places, used tires actually have a Warranty.

lxrubin said:

Three Phase:
Load KVA = Load Voltage * Full Load Amps * 1.73 / 1000
1.75kVA = 460V*2.2A*1.73/1000

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You are using motor values to calculate VA for a single phase boost transformer connected to the VFD input. What do you think is wrong with that?

You have to consider the VFD input requirement and the derating factor. You also mentioned a 240 to 480 VAC transformer.

lxrubin, I found a 3kVA Acme tranformer (240/480) for $406 (USD). A 5kVA Acme costs $614 (USD).

You can ask your question at RockwellAutomation:
https://idp.rockwellautomation.com/...tion.custhelp.com&RelayState=/app/ask_product

If you ever make it to the states, I have a 3KV.
Way To busy to ship right now and not sure if it would be practical.

Andy

eBay sold prices are all over. $80 if you ever make it this way.

A 240v:240v isolation transformer can be connected as an auto transformer to turn 240v into 480.

The power you'll get will be double the transformers rating, so you could use a 1KW 240v isolation transformer to power a 1 hp motor from a 480v vfd. its a bit small given the bad power factor drawn by the vfd on single phase, but it will work.

Thanks all. I'm going to look for a proper 1phase 240v input VFD. Maybe in my spare time I'll try to get this to work and have it as a backup or for the next machine I'll likely add to my collection.

Alex

Hobby Shop said:

If you ever make it to the states, I have a 3KV.
Way To busy to ship right now and not sure if it would be practical.

Andy

eBay sold prices are all over. $80 if you ever make it this way.

Click to expand...

I actually moved to Michigan about a year ago, but forgot to update my profile. I might IM you later if I start fiddling with this thing in the future.