A four-pole, star-connected, squirrel-cage induction motor operates from a variable voltage 50 Hz three-phase supply.

The following results were obtained as the supply voltage was gradually reduced with the motor running on no-load.

Stator line voltage                       220         164        112         88          42

Stator line current (amperes)         6.8          5.4         3.9         3.8         3.7

Stator power (watts)                   470         360        278       244        232

(a) By plotting a suitable graph from these results, determine the total of windage and friction losses, the no load magnetising current Io (assume no load current I_o is magnetising losses) and the equivalent circuit magnetising circuit parameters R_o and X_o.