A star-connected squirrel cage induction motor has the following parameters and rating: Rs = 2 ohm, Rr¹ = 3 ohm, Xs = Xr' = 3.5 ohm, V = 400V, 50 Hz, 1,380 rpm. It is driven by voltage source inverter which gives constant V/f control to induction motor. If the inverter frequency is variable from 10% of the rated frequency to base frequency. Calculate: (a) Frequency for a speed of 1,000 rpm and full-load torque. (b) Torque for a frequency of 35 Hz and speed of 950 rpm.

Subject Electrical Machines 2

Explain the DC power internal structure.

Q5- Adjust a fire angle for a three-phase full-wave semi-controlled converter to feed the separately exciter DC motor to get a load torque can be reached to 750 rpm. When the supply voltage of converter is 150 volts per-phase and the absorbed current through the armature 40A with resistance 0.2 a and a constant back emf 0.4v/rpm. Then find the maximum speed for motor assume the previous parameters values are a constant.

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.

(c) A four-pole, three-phase 415 V, 50 Hz induction motor has a rated rotor speed at 1445 rpm. The motor is connected to a constant torque load. (i) Sketch the IEEE recommended per-phase equivalent circuit for the three- phase induction motor. Label all the key components clearly. (ii) Determine the motor's synchronous speed in rpm, the motor's slip, and the frequency of the rotor current in Hertz.. (iii) If the operating frequency of the motor reduced to 40 Hz and the synchronous and rotor speed difference (n.- n,) is maintained at 55 rpm, determine the new motor's synchronous speed and rotor speed.

what is the best switch for buck boost converter and why

For a 18600W 2400rpm DC motor, the following values are given: Ra = 0.089 2 (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 1000C.) (Take the rated field winding losses as Wf= 210W.) If the motor speed is reduced to 50% of the rated speed (1200rpm), find the inductive voltage, the induced current, the motor efficiency and the motor speed at no load to obtain the rated torque at this speed. (Field supply current will be considered constant). I A V V Eff % ONL rpm

A DC, separately excited motor is used to drive a constant-torque load. The field circuit is excited by a full-wave, AC/DC SCR converter. The armature circuit of the motor is connected to a constant dc voltage source of 160 V. The inductance of the field circuit is large, and the field current is continuous. The field AC voltage (input to the converter) is 147 V (rms), and the field resistance is 100 N. The armature resistance is 1.2 N. When the triggering angle of the SCRS is adjusted to zero, the motor speed is 1000 rpm, and the armature current is 10 A. Calculate the average current and dc power of the field i. A1 F1 circuit when the triggering angle is equal to 15°. La Ra If A a P; W M • If the motor speed is to be increased to 1400 rpm, what is the F2 A2 triggering angle? (a) Circuit a =

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