3 phase to single phase

[Chris Stevens]

I dont think a 3hp single phase motor has the same torque as 3hp 3 phase. So 3hp single phase might not start something like compressor, which originally had 3 phase motor..................

 

[brightspark]

with compressors i've found you take a 3hp 3hp motro off, fit a 3hp 1ph motor and you may get problems. some work fine some just stall.

usally they'll pump up from empty fine, the real test is when it cuts back in with some air in the tank

that's what the decompressor valve is for on the pressure switch and a one way valve on the tank, no motor likes a start up under full load on a comp

 

[normspanners]

that's what the decompressor valve is for on the pressure switch and a one way valve on the tank, no motor likes a start up under full load on a comp

HUMMMMM-------- that is not me disagreeing--------- thats the sound of the motor agreeing with you BS!!
That is why I have extended my head/feed pipe round and round in a large coil at the back of the fan to increase the capacity by about 10X to help with top up starts.

 

[monkeymark]

Well after all of this the whole thing may be a non starter. Someone decided they wanted it testing to see if repairs were financially viable.
So i "broke" the motor. Now it does nothing i still stand some chance of getting it. Time will tell.

 

[dannyp]

that's what the decompressor valve is for on the pressure switch and a one way valve on the tank, no motor likes a start up under full load on a comp

yup, but a std 3 ph compressor when retorofitted with a 1ph motor still seems to struggel, as with norms post

HUMMMMM-------- that is not me disagreeing--------- thats the sound of the motor agreeing with you BS!!
That is why I have extended my head/feed pipe round and round in a large coil at the back of the fan to increase the capacity by about 10X to help with top up starts.

the compressor can struggel to get going properly before it's fighting to much pressure. hence retrofitting more volume between the head and NRV on the tank. tho my old type 30 ingersol rand needed a selonoid valve being used as an unloader due to the sheer size of the flywheel so it chould get upto speed before it had to do any work

 

[Sarto]

If I remember correctly, almost any big motor manufacturer keep in catalog the "high start torque" single phase motors.
Something like this:

http://search-ext.abb.com/library/Download.aspx?DocumentID=9AKK101130D4886&LanguageCode=en&DocumentPartId=Sect 8&Action=Launch

on page 216, starting and run capacitor.

 

[dannyp]

that type of motor fairs better than ordianary singel phase motors but a 3ph motor still has a massive advantage over it