191. If the output resistance of a voltage source is 4 Ω, it internal resistance should be

1. 3.A 3-phase ,Y- connected synchronous motor operates at 480 volt,50 Hz,2-pole,0.8 pf leading.The armature winding resistance is j1.5 ohm.The efficiency of the motor is 95%.The output torque of the motor at rated conditions is 350 Nm .Calculate: (a)the output power (b)the input power and the input current (c)the internal generated voltage Ea (d)the converted power (e)power losses (20 points)

The following three impedances are connected in series across a 40 V, 20 kHz supply: a 
resistance of 8 Ω, a coil of inductance 130 μH and 5 Ω resistance, and a 10 Ω resistor in 
series with a 0.25 µF capacitor. Sketch a neat diagram representing this network, and 
calculate:
5.1.1 The inductive and capacitive reactance’s. (4)
5.1.2 The magnitude and phase angle of the circuit impedance. (4)
5.1.3 The voltage drops across resistance, inductance and capacitance.

Question 5  (IEIIQ18)

A simple Zener shunt voltage regulator is to supply a 10 V to load of 100 mA, the input supply voltage varies between 15 V and 20 V.

5.1    Draw the circuit diagram.

5.2    Calculate the minimum power for the Zener that could be used safely in this circuit.

5.3    Using a Zener diode with a power rating of twice this minimum value.

5.4    Calculate the range of series resistance that may safely be used in this circuit and suggested a suitable standard resistance value.

Question 6  (IEIIQ19)

A voltage regulator is required to provide a regulated terminal voltage of 25 V at a maximum load of 150 mA. The input volage varies between 50 V and 75 V dc.

6.1    Calculate the minimum power for the Zener that could be used safely in this circuit.

6.2    If a 30 W rated Zener is used, calculate the range of possible series resistance, RS. values and suggest a suitable standard E12 resistor value.