Consider the following conditions for an induction motor fed by variable voltage variable frequency drive,

Air gap flux should be maintained constant.
‘V/f’ ratio should be constant.
Slip speed should be constant (Ns-Nr).
Which of the following conditions need to be satisfied for an induction motor to act as constant torque variable power drives.
Options:

1. ii
2. i and iii
3. ii and iii
4. i , ii and iii
5. i and ii