(a) You are given the following current measurements from a three- phase induction motor at time t ia(t) = 14.524 A, ip(t) -4.72111 A, i(t) = -6.92255. You are told that the number of conductors is Ns = 3,000 and the conductor length is lg = 64 mm. (1) (ii) You measure the stator field density of the motor and determine that it has a magnitude of B.(t) = 0.55 T. Use your measurements to verify the claim that the number of conductors is indeed Ns = 3,000. [6 marks] If the current ip(t) suddenly collapsed to zero, due to a fault, determine if the stator field density would still meet the requirement for a magnitude of B.(t)| >0.5. [3 marks] Given the conditions in 3(a)(w) above, state if the motor would continue to run or not. Justify your answer. Consider the motor to be a squirrel-cage motor. [2 marks] Consider that the motor is stopped and the current ic(t) also collapses to zero, due to a fault, leaving only the current ia(t) operating. State if the motor would be able to start back up or not. Justify your answer. [2 marks] (iii) (iv) (b) Discuss the use of space vectors in AC machines. [4 marks] (c) Consider a three-phase permanent magnet AC motor. You measure the clockwise holding torque, and find it to be 1,200 Nm, while the stator is supplied with a current space vector of Is = 5 kA. You are told that torque constant is equal to ky = 0.2 Nm, but you don't trust the manufacturer. Determine if the torque constant quoted by the manufacturer is accurate or not. [3 marks] (a) You are given the following current measurements from a three- phase induction motor at time t ia(t) = 14.524 A, ip(t) -4.72111 A, i(t) = -6.92255. You are told that the number of conductors is Ns = 3,000 and the conductor length is lg = 64 mm. (1) (ii) You measure the stator field density of the motor and determine that it has a magnitude of B.(t) = 0.55 T. Use your measurements to verify the claim that the number of conductors is indeed Ns = 3,000. [6 marks] If the current ip(t) suddenly collapsed to zero, due to a fault, determine if the stator field density would still meet the requirement for a magnitude of B.(t)| >0.5. [3 marks] Given the conditions in 3(a)(w) above, state if the motor would continue to run or not. Justify your answer. Consider the motor to be a squirrel-cage motor. [2 marks] Consider that the motor is stopped and the current ic(t) also collapses to zero, due to a fault, leaving only the current ia(t) operating. State if the motor would be able to start back up or not. Justify your answer. [2 marks] (iii) (iv) (b) Discuss the use of space vectors in AC machines. [4 marks] (c) Consider a three-phase permanent magnet AC motor. You measure the clockwise holding torque, and find it to be 1,200 Nm, while the stator is supplied with a current space vector of Is = 5 kA. You are told that torque constant is equal to ky = 0.2 Nm, but you don't trust the manufacturer. Determine if the torque constant quoted by the manufacturer is accurate or not. [3 marks]
