Help w/selecting Buck & Boost Transformer (208VAC-230VAC)?

[-N.]

I wish to purchase the transformer to run a 230VAC single phase compressor motor on 208VAC service.

During the course of a previous thread it was determined that my electrical service consists of 2 phases of a 3-phase 240V feed. Hot-to-hot voltage I am getting at my breaker panel is 208VAC. This is all USA 60hz. I'm not familiar with specifications for transformers, so I would appreciate some assistance in determining the specs for the purchase of a Buck-Boost transformer, so I can run the compressor without burning up the motor.

I've found a surplus Buck-Boost transformer with these specs: ACME brand,Catalog #: T-1-81047, Style: ER, Primary Volts: 120 x 240, Secondary Volts: 12 x 24, Single Phase, .050 KVA, 50/60 Hz, Winding Rise 80, Degree C. Enclosure type: 3R Outdoor, Insulation System: B-3223-M Class 130

Would that suit my application? If not, what specs do I need to correctly and safely boost my service to

230VAC? Once again, many thaks for the assistance! Neal

[RTH]

Need to know what your amp load is a 230V in order to size the BB properly.

RT

"-N." wrote:

[-N.]

On Mon, 29 Dec 2003 18:28:57 -0400, RTH wrote (in message ):

The motor is rated at 22FLA. Is this the figure that's needed? I do not know starting amperage if the motor, though if needed I could get that info. This motor will be the only load on this circuit.

[RTH]

Don't think .050 kva is going to be big enough. Acme does not list selection tables on it's website. I checked another manf. Hevi-Duty Elec and there bb tables indicate that you need a .750 kva to boost 208 to 229 and will handle

31.8 amps. A .500 va will handle about 20 amps.

Suggest you try contacting a local Electrical Dist like Graybar Elec Supply or may WW Grangier for more info. They probably have what you need in stock.

RT

"-N." wrote:

[Dennis J Brown]

I have one that they were throwing away at work. It is still on my bench I will look and see what the rating is when I go back in Monday.

[Lew Hodgett]

RE: Subject

Go to any decent industrial electrical distributor.

Selecting a B/B x'fmr is a very straight forward thing.

All the x'fmr manufacturers publish selection tables.

All you need is input voltage, output voltage, and motor HP.

HTH

[-N.]

On Tue, 30 Dec 2003 1:26:55 -0400, Dennis J Brown wrote (in message ):

Thanks Dennis.

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Swap out the air for lovegasoline to make contact.

[-N.]

On Mon, 29 Dec 2003 22:20:42 -0400, RTH wrote (in message ):

I called SQUARE-D and was told .75 KVA was correct for my application.

Another question is whether to use a 12/24 volts secondary or 16/32 volts secondary. The gent at Square D claims that the 12/24 will give 230VAC output; the 16/32 will yield 236VAC output....these figures assuming consistant 208VAC input voltgae. He also said that although the motor is listed at 230VAC, the specs for motors have a wider voltage tolerance (I think he said it was 15% above & 10% below the listed voltatge). He felt that either Booster would work (the 16/32 however would then be rated at .50KVA for my application instead of the .75KVA rating of the 12/24). Anybody see any great advantage of the one over the other (I may possibly be able to get a 16/32 cheaper)?

On installation: does the Booster get installed downstream of the disconnect box (service panel-booster-disconnect box-motor)? Any other hardware needed to complete a booster circuit or is it pretty much just the Booster transformer wired into the circuit? Thanks again. Neal

[Wild Bill]

I see that the compressor cut-off is 170 in your latest post. That's a nice air supply if you have a demand for that much air.

I think the current drawn by the motor will be it's highest at 170. Instead of getting a transformer, I'd just reset the pressure switch cut-off for to about 140, and lower the cut-in a little.Another approach would be to reduce the size of the motor pulley, but resetting the pressures would be easier.

If you had high air demands, this wouldn't be a practical approach, but in a home shop, it shouldn't matter much. If you're using a lot of air on a daily basis, it will be more costly to operate the unit this way, with an increase in the amount of times the motor cycles on.

I don't know if the starter has a motor current protection trip in it, but you might want to check for that. If the unit has motor thermal protection plus current protection (that are operating properly), it's unlikely that you'll burn out the motor.

WB ..............