For a 18600W 2400rpm DC motor, the following values are given: Ra = 0.089 O (value at room temperature (250C)), La = 0.00144 H, KT = 0.85 Nm / A and KV = 0.851 V / (rad / s)), (In calculations Use the hot resistance values at 100oC.) (Take the rated field winding losses as Wf=210W.)

A four-pole induction motor drives a load at 2405 rpm. This is to be accomplished by using an electronic converter to convert a 400V dc source into a set of three-phase ac voltages. a) Find the frequency required for the ac voltages assuming that the slip is 4 percent. The load requires 2hp. b) If the dc-to-ac converter has a power efficiency of 93 percent and the motor has a power efficiency of 80 percent, estimate the current taken from the dc source.

Sketch the torque versus speed characteristic for a series-connected dc motor.

1. A fundamental DC motor is shown below. VTerminal = 90V. The running current, I = 5A and the rotor resistance, R = 4 ohms. Answer the following: CEMF or E at the running condition = , Power delivered by the source at the running condition = Power converted to mechanical power at the running condition Power lost in heat by the rotor resistance = Show your work for each calculation. Suggest that you clearly mark the schematic. frut