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question for the electrical engineering types = VFD 3 phase stuff


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The single phase motors will have caps and likely a centrifugal switch to transfer from the start to run winding, at 230V and 5hp you could see some fairly high amps for a brief period while it's coming up to speed, the unloader will need to be working properly so it's not fighting against the tank pressure

Just went through all this with an IR compressor, Quincy is tops IMHO, you might need a little bit of control wiring mods as I would assume your contactor is now 3 phase, might be able to leave the 3rd contact empty

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1 hour ago, searcyfarms said:

No, it just provides 3 phase. There is no reason for a VFD for your use. The compressor when wired through the digital phase shifter  will run at the designed speed. This device is for exactly what you are doing. Needing to run a 3 phase motor when you only have single phase available.

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25 minutes ago, TomH said:

No, it just provides 3 phase. There is no reason for a VFD for your use. The compressor when wired through the digital phase shifter  will run at the designed speed. This device is for exactly what you are doing. Needing to run a 3 phase motor when you only have single phase available.

ok nice way cheaper than a motor i can try it and if i get along with it ok save some $$$ - that phase shifter is rated at 23 amps and the motor is 14.8 so that will give it a little buffer. 

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Since the compressor motor is 5 hp, I would swap to a single phase motor.  That will be the simplest long term. I did just that years ago. Bought an Ingersol Rand T30 style with a 5 hp 3 ph motor. We had a 7.5 hp single ph silo unloader motor so swapped that on and never touched it again. That was almost 20 years ago. 
I have a rotary phase converter in my shop and I wouldn’t care to run a 3 ph compressor. I don’t want the RPC running 24/7, but I don’t want the complexity of having to power up the RPC, and when it’s spun up connect the compressor, then reverse the process when the compressor shuts down. 

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22 minutes ago, Gearclash said:

Since the compressor motor is 5 hp, I would swap to a single phase motor.  That will be the simplest long term. I did just that years ago. Bought an Ingersol Rand T30 style with a 5 hp 3 ph motor. We had a 7.5 hp single ph silo unloader motor so swapped that on and never touched it again. That was almost 20 years ago. 
I have a rotary phase converter in my shop and I wouldn’t care to run a 3 ph compressor. I don’t want the RPC running 24/7, but I don’t want the complexity of having to power up the RPC, and when it’s spun up connect the compressor, then reverse the process when the compressor shuts down. 

i just purchased one of those DPS Digital Phase Shifter MY-PS-7.5 23A 7.5HP units

 found one for 150 free shipping - will see how it goes when I get everything ready to test for smoke

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I have been working with 3 phase ac for over 60 years, both 60 HZ and 400 HZ (old time aircraft ac distribution).  If you have a unique situation with a special 3% motor the phase converter is probably the only solution, if you do not  have commercial 3% power available BUT for a simple air compressor with a standard ac motor I would just replace it with a single % at the the same footprint, Voltage, duty cycle and RPM. 

I always like the KISS, or keep it simple!

 

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2 hours ago, searcyfarms said:

ok nice way cheaper than a motor i can try it and if i get along with it ok save some $$$ - that phase shifter is rated at 23 amps and the motor is 14.8 so that will give it a little buffer. 

Unless it has the specific capability 23A is not sufficient to start that compressor, you would likely see a voltage spike of maybe 40 a on startup. A magnetic motor starter has the capability of withstanding that long enough to get a motor running. That device may or may not. 

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9 minutes ago, nomorejohndeere said:

Gas engine that bad boy 

 

 

 

Pto

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4 hours ago, vtfireman85 said:

Unless it has the specific capability 23A is not sufficient to start that compressor, you would likely see a voltage spike of maybe 40 a on startup. A magnetic motor starter has the capability of withstanding that long enough to get a motor running. That device may or may not. 

well if it doesnt work i will just sell it to you guys then and buy a bigger one dang it

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4 hours ago, vtfireman85 said:

Pto

yes going to hook up the prius PTO  to it and run battery/solar power - maybe hook a fan up also with solar to keep cool cause my shop ac went out and im trying to boon doggle one off c/l or faceplant - cmon prius dont fail me now.......wait i dont have one - i just woke i was having a nightmare about brandon

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One more vote here for a 1PH motor. My compressor looks similar yours except the compressor is V rather than upright. It's a big name that escapes me now. I got a really great deal on it just because it was 3PH. Looked at converters and decided to change the motor. i found a surplus one with the same frame and speed and still came out money ahead. I'm pretty sure I used the same contactor too as it offered wiring for both single and three phase. It's been running faithfully for 30 years. Changed the valves a few years ago.

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12 hours ago, oleman said:

400 HZ (old time aircraft ac distribution).

I had a 727 come in with a pack fan written up as replaced fan motor, new one wired wrong. I checked it and it was running backwards. Swapped two leads and voila! Fixed.

The pack fans came on at low speeds or when the gear was down to draw more air across the air cycle machine heat exchangers. The air cycle machine take hot engine bleed air and turns it into cold air.

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8 hours ago, searcyfarms said:

well if it doesnt work i will just sell it to you guys then and buy a bigger one dang it

The motor starting capacity is built in to the DPS. Only use the specific size, IE 5 to 7.5hp. Using a larger one will not work and may damage something.

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6 minutes ago, TomH said:

The motor starting capacity is built in to the DPS. Only use the specific size, IE 5 to 7.5hp. Using a larger one will not work and may damage something.

well maybe it will work after all then will know soon, i pick up the compressor tonight and should have the dps first of week provided shipping comes thru - great to know it should start/run the motor fine, its a 5 hp unit rated around 15 amps and the dps shows max 23 for 5 to 7.5 hp motors 

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16 hours ago, hardtail said:

The single phase motors will have caps and likely a centrifugal switch to transfer from the start to run winding, at 230V and 5hp you could see some fairly high amps for a brief period while it's coming up to speed, the unloader will need to be working properly so it's not fighting against the tank pressure

Just went through all this with an IR compressor, Quincy is tops IMHO, you might need a little bit of control wiring mods as I would assume your contactor is now 3 phase, might be able to leave the 3rd contact empty

i have a quincy already but couldnt afford another so was looking for a descent replacement and this one came across my radar - we have a prehistoric curtis up home but its a museum piece and parts NLA for it. It it might become a bbq smoker for someone LOL its a heavy old tank 

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15 hours ago, oleman said:

I have been working with 3 phase ac for over 60 years, both 60 HZ and 400 HZ (old time aircraft ac distribution). 

Off subject...I have a couple old generator heads 300 HZ I think the guy at the garage sale said I think B52 . They are air craft for sure, tie wire and such. I have hung on to them for forty years or so thinking that some day I might come across a use for them. Do you have any ideas?

Searcey , get a refund and buy a 1 PH motor TEFC, it is not cheep but will pay you back for the rest of your life, untouched.

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1 hour ago, just Dave said:

Off subject...I have a couple old generator heads 300 HZ

I never touched a B52 but every aircraft with an AC system that I know of is 400hz. There are some corporate aircraft that have wild frequency AC that's rectified to DC - a weight saving idea, I guess.

There used to be lots of smaller and older planes with a DC system with inverters to supply instruments that ran on either 208 or 26 volt AC but just about everything now is 28 volt DC. Gyros, Inertial Navigation Systems all wanted AC in the past but now the rotary inertial have been replaced by laser types that align in just couple of minutes and are DC. Our planes are all DC except for the in-tank fuel pumps which are AC and each has its own inverter.

I don't know what the airline aircraft use now. The newest thing I ever worked on were 757s and they were 208 400hz 3ph.

Anyway, get the P/Ns off your generators and put them on Ebay with the B52 info. Maybe there's a market for memorabilia. 

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2 hours ago, just Dave said:

Off subject...I have a couple old generator heads 300 HZ I think the guy at the garage sale said I think B52 . They are air craft for sure, tie wire and such. I have hung on to them for forty years or so thinking that some day I might come across a use for them. Do you have any ideas?

Searcey , get a refund and buy a 1 PH motor TEFC, it is not cheep but will pay you back for the rest of your life, untouched.

I would expect to see a 400 HZ system on a B52.  My exposure on  400 HZ came from shipboard electronics where certain equipment was shared between ships and aircraft.

I am a collector of many items but the only thing I have that operates  at 400 HZ is a function generator.

We had a piece of electronics from an aircraft with a 3% 400HZ 115V 23,000 RPM fan motor, about the size of a cigarette pack. Sounded like a Kirby vacuum cleaner on a turbocharger,  that motor required new bearings every 3 months.  Just think of ball bearings at that speed, made by the lowest bidder, on a government contract.

 

 

 

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15 hours ago, searcyfarms said:

yes going to hook up the prius PTO  to it and run battery/solar power - maybe hook a fan up also with solar to keep cool cause my shop ac went out and im trying to boon doggle one off c/l or faceplant - cmon prius dont fail me now.......wait i dont have one - i just woke i was having a nightmare about brandon

I wuz jist gonna tell you to put a windmill on it, but sounds like you and ol’ Brandon got it figgered out

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On 6/7/2022 at 11:07 AM, jeeper61 said:

image.thumb.png.25718f2073b1e673160bb6e02d093c3a.png

funny you picked that motor its the one the baldor tech/engineer guy told me to get, the farm duty has a lot more starting torque and he said unless youknow for sure the device will take the start torque you might be wise not to risk it - the farm duty line is nearly double the start torque

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2 hours ago, searcyfarms said:

funny you picked that motor its the one the baldor tech/engineer guy told me to get, the farm duty has a lot more starting torque and he said unless youknow for sure the device will take the start torque you might be wise not to risk it - the farm duty line is nearly double the start torque

Look around I saw it on Zoro for 854 free shipping 

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5 hours ago, oleman said:

I would expect to see a 400 HZ system on a B52.  My exposure on  400 HZ came from shipboard electronics where certain equipment was shared between ships and aircraft.

I am a collector of many items but the only thing I have that operates  at 400 HZ is a function generator.

We had a piece of electronics from an aircraft with a 3% 400HZ 115V 23,000 RPM fan motor, about the size of a cigarette pack. Sounded like a Kirby vacuum cleaner on a turbocharger,  that motor required new bearings every 3 months.  Just think of ball bearings at that speed, made by the lowest bidder, on a government contract.

 

 

 

Our building air conditioning compressors run at 35000 rpm, magnetic levitation 

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