# Assignment-II -Subject-Electrical Machines

Friday, March 20, 2020

**Edit****Assignment-II**

Synchronous Motor & Power Devices

**Subject_ Electrical Machines**

1) Draw and explain
Equivalent Circuit and Phasor Diagram of a Synchronous Motor at lagging power
factor.

2)Write applications of 3-ph synchronous
motors.Also Compare 3-ph synchronous motors with 3-ph Induction motors.

3) Explain Operation with 3-phase Synchronous motor constant load and variable excitation with suitable phasor diagram and graph.

4) Explain Operation of 3-phase Synchronous motor with constant excitation and variable load.

5)Write power and torque equation of synchronous motor

6) A 50 HP 410 V 50 Hz 3 phase star connected
synchronous motor has full load efficiency of 85%. The synchronous impedance of
the motor is (0.2 + j 2.0) Ω per phase. If the excitation of the motor is adjusted
to give leading p.f. of 0.85. Calculate : i) Full load induced emf line value.ii) Mechanical power developed.

7)Explain construction detail and V-I
characteristics of TRIAC.

8)Explain and draw output and Transfer characteristics of MOSFET and IGBT.

9)Based on application and construction distinguish SCR and TRIAC

**Assignment-II**

**Synchronous Motor & Power Devices**

**Subject_ Electrical Machines**

**SET-B**

1) With suitable voltage equation of Synchronous motor draw and explain
Equivalent Circuit and Phasor Diagram of a Synchronous Motor at lagging power
factor.

synchronous motors also write applications of 3-

ph synchronous motors.

3)
Explain 'V' curves and inverted 'V' curves in case of
three phase synchronous motor.

4) Explain Operation of 3-phase
Synchronous motor with constant excitation and variable load.

5) The
efficiency of 3-phase , 400V star connected synchronous motor is 95% and it
takes 24A at full load unity power factor. what will be induced emf and total
mechanical power developed at full load and 0.9 power factor leading? The
synchronous impedance of the motor is (0.2+2j) ohm/phase.

6)Draw and explain power flow in synchronous motor

7) Explain construction detail and V-I
characteristics of DIAC.

8)
Explain Construction details and draw output and Transfer characteristics of
IGBT.

9) Explain construction detail, application and
V-I characteristics of SCR.

10)Based on application and construction distinguish DIAC and TRIAC