Synchronous and Full-Load Speeds
of AC Induction Motors

No. of
Poles		 60 Cycle R.P.M. 50 Cycle R.P.M. 40 Cycle R.P.M. 30 Cycle R.P.M. 25 Cycle R.P.M.
Sync. Full
Load		 Sync. Full
Load		 Sync. Full
Load.		 Sync. Full
Load		 Sync. Full
Load
2 3600 3500 3000 2900 2400 2310 1800 1750 1500 1450
4 1800 1770 1500 1450 1200 1150 900 860 750 720
6 1200 1170 1000 960 800 770 600 575 500 480
8 900 870 750 720 600 575 450 375 375 360
10 720 690 600 575 480 460 360 340 300 285
12 600 575 500 480 400 385 300 285 250 240
14 514 490 428 410 343 330 257 247 215 205
16 450 430 375 360 300 288 225 215 187 180
18 400 380 333 319 266 256        
20 360 340 300 285 240 230        
22 326 310 273 260 218 208        
24 300 285 240 230 200 192        
30 240 230 200 192 160 153        

The speed of the AC squirrel cage induction motor is determined by the frequency of the supply system and the number of poles for which the motor is wound:

Sync RPM = (F x60) xP

where F is the frequency of supply in cycles per second and P is the number of pairs of poles.
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