A 100 MW coal fired power plant has an average heat rate of 9,500 BTU/ kWh. The plant load factor is 75%; the heating value of coal is12,000 BTU/ lb. Calculate the amount of coal usage for one day.

a. 1.425 x 106 lbs.

b. 2.235 x 105 lbs.

c. 1.425 x 106 lbs.

d. 1.826 x 106 lbs.

Kindly solve the below questions:

1. Assume the AC frequency is 50 Hz. Convert these phasors to signals (remember that phasor magnitudes are RMS values of the signals)

    (a) V = 115∠90V

    (b) I = 10 + 10j A

2.  Convert these signals to phasors (remember to us RMS values for the phasor magnitude)

    (a) v(t) = 230cos (314t + 20) V

    (b) i(t)  = 5cos (314t + 10) A

3. Suppose the voltage across a load is v(t) and the current drawn is i(t) where 

v(t) = 230cos (314t + 20) V

i(t)  = 5cos (314t + 10) A

   (a) calculate the complex power, real power, reactive power and apparent power.

   (b) calculate the power factor and indicate if it is leading or bagging

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.

Question 3  (IEIIQ16)

A 3 W rated Zener diode is used in a shunt voltage regulator circuit to supply a dc output of 12 V to a variable load with a minimum resistance of 240 Ω. The supply voltage varies between 20 V and 24 V.

3.1    Draw the circuit diagram.

3.2    Calculate the range of series resistance that may safely be used in this circuit. Select a single suitable standard value.

3.3    Calculate the maximum power rating required for the series resistor.

Question 4  (IEIIQ17)

A simple Zener voltage regulator is required to provide a steady regulated output voltage of 10 V under a maximum load of 80 mA, while the input voltage to the regulator varies between 12 V and 14 V.

17.1  Calculate the maximum rated current value of a Zener diode to be used

17.2  Calculate the minimum power for the Zener that could be used safely.

17.3  If a 5 W rated Zener were to be used in this circuit:

(i)      Calculate the maximum rated current value of a Zener device to be used

(ii)      Calculate the range of possible RS.  limiting resistor values.

(iii)     Suggest a suitable standard E12 resistor value