Which Motor You Recommend: Single or 3 Phase?

We use 3 phase above 2.2KW.Go for single phase.What is FLA?

I advice you use 3 phase motor.

FLA stands for Fully loaded Amp rating based on a locked rotor condition. Motors typically have a maximum current rating to size relays and such that are switching power to the motor.

We use 3 phase above 2.2KW.Go for single phase.What is the FLA?

It doesn't matter which one is used, "Keeping aside cost factor".

I'm assuming that 3 phase is available, but, if money is no object, that doesn't matter either.

Thanks everyone! Say for example my load is a Vacuum Pump or Air/ Gas compressor. What I mean is if starting torque is very high, "single phase" is recommended or can I still use 3 phase? I see only advantage with single phase motor is that, we can run where 3 phase supply not available and simple series or triac speed control; since cost does not matter one should prefer 3 phase as all 3 phases will be well balanced!

It doesn't really matter, given the lack of constraints in the original post.

I think three motors are more efficient than single phase motors if we calculate entire electrical energy (starting currents, sudden jerk load currents, etc) is taken in to consideration; particularly in case of Capacitor-start-and-capacitor-run motors that are used in Air conditioning/ refrigeration compressors,

Actually, depending on how much torque is needed at slow speeds, you might do better with a DC brushed motor. There are just to many variables that will very rarely be fully known and understood to properly say which motor is the "ideal" motor for an application.

To be fully honest, I'm dodging your question. Getting a rotating magnetic field with only one AC phase will always produce compromises leading to inefficiencies under some loading conditions. Because of this I recommend three phase over single phase for powering a motor. But this is only true if one can find or fabricate the ideal motor of each configuration and have them drive identical mechanical loads. My stipulations of identical mechanical loads and identical electrical loss design of each motor to measure the accuracy of my claim would be tricky to assemble and test in a laboratory, it will not happen from buying off the shelf motors to make comparisons. So there will be applications that a particular single phase motor will work more efficiently than a particular three phase motor.

I always go for 3-phase because they are generally much smoother than single-phase motors (vibration-wise).

I ran a 3-phase mill from a cheap phase converter that basically power a 2nd phase with a capacitor (phase shift) to get the motor started and then the converter would revert to single-phase.

Switched to a VFD unit to drive the same motor and the mill runs much smoother. So much so that I'm converting my lathe over to 3-phase as well.

Interesting bit is that modern motors are apparently not balanced at the factory. Every motor we test can benefit by some dynamic balancing. Makes a great difference in surface finish on work. I suspect that lower vibrations also are good for bearings and other moving bits.

Capacitor start single phase motor can give upto 300% starting torque. Capacitor start and run motors ahve much lower starting torque. Stay away from split phase motors for this application since the starting torque is afraction of full load torque.

fluid coupling is another option.

I would go with a 3 phase Design C high starting torque motor as most reliable. Being less dependent on a single phase being overloaded or having simultaneous starts on a single phase system lends some uncertainty to the use of higher horsepower motors on single phase systems not to mention the current draw/voltage drop of a 1 HP single phase vs a 3 phase operation.

If one is <...Keeping aside cost factor...>, responses will be based on preferences and availability.