three-phase motor turns 380v to single-phase 220v.

[Homer66]

I turned around the forum a bit, but I didn't find any feedback, so I'm here asking for delucidations.
I'm turning a three-phase motor into a single phase to use it in 220.
I ask those who know more about me in the electromechanical field: knowing that with such change (from 380 to 220) I will have a performance decrease of 30% (I found it on the net...), in regard to the turns/min I will have the same decay?
then becertainly translated: if in three-phase I had 3000, in monophase I will have 2000 rpm?
Fatty.

 

[marcok625]

hello, should not change the rotation speed because linked to the frequency not to the voltage.

 

[marcok625]

attention that:

the speed of the rotor in nominal conditions is always less than a 3-6%; it is the phenomenon of slider (slip) allowing torque production. from the formula that defines it slider it is possible to express the actual rotation speed of the rotor (nr ):

{\displaystyle s={\frac {n_{s}-n_{r}}{n_{s}}}}}

where s è lo scorrimento, ns is the speed of synchronism and nr is the real speed to which the rotor rotates.

the actual value of the slide depends on the actual load on the rotor. the load is never null because there are always the phenomena of friction between the moving parts and the air that prevent the motor to rotate at the speed of synchronism, winning this mechanical couple.

cast iron https://it.wikipedia.org/wiki/motore_asincrono

 

[meccanicamg]

lose power but do not turn. insert a condenser that does the function of the third phase then always working at 50hz network you have the same speed.

 

[Homer66]

thank you all warmly for the infos