TESTS OF INDUCTION MOTORS. 



167 



From these details we see that induction motors compare 

 favourably with the best shunt-wound direct-current motors, 



,7% 



30 



B.H.R 



FIG. 69. Characteristic curve of a brake test for a 5 B.H.P. single-phase motor. 

 100 cycles. 200 volts. 2000 revs, per min. 



both as regards efficiency and constancy of speed under variable 

 loads. 



Output of Motor expressed as Horse Power 



FIG. 70. Brake test of a 10 B.H.P. three-phase motor. 190 volts. 50 cycles. 

 1000 revs, per min. 



The chief objection to such motors is that no easy means has 

 been devised for varying their speed. It is possible, as has already 



