3 Phase compressor, single ph service: What options?

[pescador775]

I don't get the dryer deal except that a dryer plug may be three prong (old) or four prong. Breakers are normally 40 Amperes. Even so, I would not want to carry that thing equipped with a 7.5 hp motor.

 

[Fl_Key_Guy]

A dryer circuit is 30 amps I believe.

I was going to put this thing in a trailer anyway since Monroe County (FL Keys) and FEMA are such jerks about downstairs enclosures and equipment below the 100 year flood plain, blah, blah, blah. So it will be easy to carry with the truck!

A long enough 10 gauge power cord could connect me to a friend's dryer outlet. But if a slower speed won't work then neither will a 5 hp motor...

 

[pescador775]

Yeah, I checked, standard dryer circuit breaker is 30A. My bad.

 

[mike_s]

a standard dryer outlet is 30amp, but a pain in the butt to run a longer cord into the house to the dryer, have to move the dryer, unplug it, then do the same in reverse afterwards....

just spend a couple bucks and get a outlet mounted out in the garage near the place you want to hook it up on your trailer. A little eaiser in the long run not having to deal with the plug behind the dryer anytime you want to use it.

that and you don't have to listen to the wife/other fuss that they con't use the dryer and having the door cracked open letting bugs in and AC out while the compressor is on. compressors aren't quiet also, so you'll like having that door closed.

might want to consider a GFCI breaker since you're running it outdoors. (I think you'll find that NEMA & NBC code specifies a GFCI outlet or breaker in most outside locatioin anyway.)

 

[dannobee]

You guys have it all wrong. Yacht generators are three phase and this compressor was made for a yacht. Buy a yacht and your troubles will be over (at least with respect to powering the compressor).

I hear there are a lot of them for sale in your area, too. We'll all chip in for some gas when you get it. Get a big one so we can all sleep over.

But seriously, If it's going on a trailer anyway, have you considered a small diesel engine like the Yanmar's that are offered with some of the Bauer's?

 

[mike_s]

yeah... if I had a yatch big enough for a 3-phase generator, all my problems would be solved...


as for a trailer generator, have you priced a 3-phase generator lately? **ouch**

(we use 3-phase generators at work (on trailers), they aren't cheap).

 

[Fl_Key_Guy]

The yacht idea sounds good, but I'll need a benefactor and a huge debit card for fuel and mooring...

I am seriously looking at a 3 phase propane generator that would also run the house. (My power just came back about a half hour ago- having a brush by hurricane Ike THIS week). Used, $900.

I don't think they make GFI dryer receptacles- that would require a GFI breaker. GFCI is not so foolproof either- I've fooled myself into shocks at least 3 times on them. And yes, they were "exercised" and operable. They will only protect you from carrying current from hot to soil or the electrical ground. But I'm rambling off the thread...

Any more info on running the compressor at only 800 rpm?

 

[CraigAClark]

As I asked before, does the unit have a Mariner or Mariner II block. 2003 would be in the realm of still having the Mariner Block available. Bauer made the change to the Mariner II block around this time. Brownies would not have changed the model because of the block change. So you see, I can't tell you what block is on your unit. You can tell very easily what block you have. The Mariner has an oil pressure regulator attached to the side of the 3rd stage. There is a clear sight glass on the regulator. This regulator is not present on the Mariner II. The Mariner has a dipstick for checking the oil level, which is located on the left side of the first stage (facing the side opposite the flywheel). The Mariner II has 2 oil level sight glasses, located on each side at the bottom of the crank-case, facing the side opposite the flywheel.

800 rpm is too low. The Mariner can be run at 1100 rpm. I can give you the model number of a Leeson, single phase, 5hp motor which will work. The motor is ODP, but it has one of the lowest amp draws of any 5hp motor I have found, 20.5 FLA. Since we are a Leeson Distributor, I can tell you whether it is in stock at their Miami location and may be able to help you on the price. You can also install a TDR on the auto drain circuit which will keep the unit "unloaded" until it has reached full speed.

Craig

 

[mike_s]

I am seriously looking at a 3 phase propane generator that would also run the house. (My power just came back about a half hour ago- having a brush by hurricane Ike THIS week). Used, $900.

Not sure how big it is, but regardless, $900 for a 3 phase generator of any size is pretty cheap.

Propane is a lot more stable for long term storage such as for emergency outages also than gasoline is.

I don't think they make GFI dryer receptacles- that would require a GFI breaker.

I said GFCI breaker above. (as I've never seen a GFI dyer receptacle either.)

I only reference recepatacle & GFCI when I said in most places it was a code requirement for an outside electrical device.

 

[Scuba Duck]

You can accomplish both desires (speed reduction and 3 phase AC) with the same appliance. Look for Variable Frequency Drives on Ebay. This is a device that turns single phase AC into DC current then into 3 Phase AC curent at whatever frequency (rotational speed) you want. You will be able to slow the compressor down if desired while keeping the more reliable 3 phase motor.

Here is one I found on EBAY, new that is rated for 7.5 HP.

Variable Frequency Drive Inverter VFD NEW 7.5HP 5.5KW - eBay (item 140263806015 end time Sep-13-08 06:00:36 PDT)

You may be able to find a used one for considerably less.

50 Amp breakers are commonly used for Ranges (Ovens).

GFCI's don't protect you from getting shocked. Should a Ground Fault occur, ie the ground wire to the GFCI outlet or GFCI breaker no longer connects to an effective ground, the circuit in the GFCI will open and secure power. You can still shock yourself by providing the current path from hot to cold. And if the appliance you are using does not have a ground wire (the typical hair dryer for example) the GFCI doesn't really provide any level of protection.

208V 3 Phase is really 240 volt.

Standard single phase generally has two 120 volt power wires (with respect to neutral or ground) that are 180 degrees out of phase. 2*120*Sin(180) = 240 volts as measured on your volt meter.

3 phase power has each phase 120 out of phase with the next, with each power wire at 120 volts with respect to ground or neutral. 2*120*Sin(120) = 208 volts as measured on your volt meter. So when you measure between two phase of a 3 phase circuit, your meter will read 208 volts. But if you measure between one of the phases to ground, your meter will read 120 volts.