# Induction motor and synchronous motor

Discussion in 'Homework Help' started by davehol, Mar 2, 2010.

1. ### davehol Thread Starter New Member

Mar 2, 2010
3
0
An industrial plant is supplied by the electric utility with 3 phase, 4160 V(line to line), 60 HZ. The total plant load is 5000 kW (3 phase). Each major process in the plant now runs with an induction motor that has a power factor of 0.85 lagging. It has been suggested that one of these major process can be converted over to a synchronous motor, which would also improve the overall power factor. The proposed machine has a series reactance per phase, Xs=6 ohms. It will serve a process that requires 2000kW after installation.
a) Find the current delivered to the plant by the utility before replacement of the induction motor by the synchronous motor.
b) The synchronous motor (Y-connected) is installed and set up to draw 2000 kW (out of the same 5000 kW) and S=2750 kVA with a leading power factor. What is the current delivered to the plant now? What is the plant's overall power factor?
c) With the motor in place, drawing P=2000 kW and S=2750 kVA (leading), find the torque angle and the internal voltage magnitude Ea (line to neutral) in the machine.

2. ### davehol Thread Starter New Member

Mar 2, 2010
3
0
I just cant figure out part c on this problem.

3. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
784
Re part (c) - Are you familiar with the the round rotor phasor diagram - leading current form?