Electrical Engineering Answers

If Eth =199.45V with an angle of - 56.31 degrees Zth =8.32 with angle - 3.18° Using the maximum power transfer theorem, determine P max.

a. 1198.2 VA 

b. 1198.2W 

c. 1198.2 KW 

d. 1198.2 VAR

For a compound circuit R series with XL , R = 3 omega and XL = 6O omega connected with parallel branches R = 2 omega and XC = 8 omega E=30 V 0° Find source (IT) .

a. 4.07 A 48.57°

b. 4.07 A -48.57°

c. none of the above

d. 48.57 A -4.07 °

Using cascading, design an active low pass filter with the following specifications:

A_MAX = 1 dB

A_MIN = 30 dB

f_p = 20 kHz

f_s = 40 kHz

The filter order N should be as small as possible. Choose only from the filter that you have studied. Draw your circuit and show all calculations for the component values, with justifications explained (where applicable).

You are required to design the heatsink for the power transistor of a voltage regulator, keeping the heatsink cost minimal. The voltage regulator has an output voltage of 5 V and a full load current of 500 mA. At full load, the regulator efficiency is 25 %, with the power transistor contributing to 45% of the power loss. The regulator is expected to operate at ambient temperature of between 20 °C and 40 °C. The heatsink temperature should not be more than 80 °C. Assume the cost of the heatsink is inversely proportional to the value of the thermal resistance θ_SA. The power transistor has the following parameters: θ_JC = 3 °C /W TJ, max = 150 °C Determine the thermal resistances, θ_CS and θ_SA.

Isolated dc-dc converter is switched at 30 kHz with a duty cycle of 0.65. It is supplying 48 Watts load. The turn’s ratio of the centertapped transformer is 6.5. The dc link of this converter is taken from 48 V battery. The output inductor value is 10 mH. The output inductor current ripple is 12 % of load current. Determine following parameters for half bridge, full bridge and push-pull dc-dc converters (i) output voltage (ii) average and rms current of secondary diode (iii) voltage developed across the primary switch when it is off (iv) peak inverse voltage of secondary diode.

A flyback converter is switched at 50 kHz with a duty cycle of 0.4. It is supplying 25 Watts load. The turn’s ratio of transformer is 5. The input voltage of this converter is derived from 12 V battery. The flyback inductor value is viewed from the primary side is 10 mH. Determine (i) output voltage (ii) voltage developed across the primary switch when it is off (iii) peak current through the primary switch (iv) peak inverse voltage of secondary diode

Design the flyback converter for following specifications: Vin = 18 V, Switching frequency = 25 kHz, Vo = 7.5 V, Po= 30 W. Assume necessary data if required.

A three phase 11KV transmission line supplies a 3MW load of 0.8 lagging power factor. Each transmission line phase has a series resistance of 0.01 ohms and an inductance of3x104 Henries. If the power factor of the load is improved to unity. What is the supply voltage needed to give rated voltage at the load and the relative phase angles of the supply and load voltages? [11.0027KV 0.13°]

This task requires you to write a report on the growing development in networking technologies. Your report should include important features such as: memory capacity, wireless implications, smart sensors, control software etc.

Your report should show evidence of independence research. You should also include a bibliography.

The safe range of operation of a temperature controlled chamber is to be indicated by means of a green LED which should glow when the temperature is between 25 and 45 degrees above the ambient temperature. A green LED has a typical forward cut-in voltage of 3.3 V. If the temperature sensor of choice is a Pt100 RTD, with a nominal value of resistance Ro = 100 , temperature coefficient of resistance  = 3.85*10-3 / oC and a maximum safe current of 100 A, design a circuit to obtain the above, provided that the maximum current through the LED is to be limited to 10 mA. = ohm