Power Generation MCQs Part 20

Contents

- 1 Mechanical energy is supplied to a DC generator at rate of 30000 J/s. The generator delivers 35 at V. The efficiency of generator is:
- 2 Certain power station has connected load of 40 MW and maximum demand of 20 MW. Per annum, the units generated are 50.5*10^6 kWh. The demand factor is
- 3 A 200 MW power station delivers 100 MW for 3 hours, 50 MW for 7 hours and remains shut down for rest of each day. It also remains shutdown for 50 per year. The energy supplied per year is
- 4 Economizers in thermal power stations are used to heat:
- 5 If, power P available from hydro-scheme is given by formula P = 9.81 QH where Q is flow through turbine in litres/s and H is head in metres then P will be in units of

## Mechanical energy is supplied to a DC generator at rate of 30000 J/s. The generator delivers 35 at V. The efficiency of generator is:

Mechanical energy is supplied to a DC generator at rate of 30000 J/s. The generator delivers 35 at V. The efficiency of generator is:

- 9198
- 8198
- 7198
- 6198

Correct answer: 1. 9198

Solution:

Units generated per annum = Max demand * LF * Hours in year

= 30000 * 0.35 * 8760

= 91980000

= 9198 * 10^4 kWh

## Certain power station has connected load of 40 MW and maximum demand of 20 MW. Per annum, the units generated are 50.5*10^6 kWh. The demand factor is

Certain power station has connected load of 40 MW and maximum demand of 20 MW. Per annum, the units generated are 50.5*10^6 kWh. The demand factor is:

- 35.1 kW
- 45.1 kW
- 55.1 kW
- 65.1 kW

Correct answer: 1. 35.1 kW

Solution:

Average demand = Units generated per annum/Hours in a year = 50500000/8760 = 5765 kW

——————

Load factor = Average demand/Max deamnd = 5765/(20 * 10³) = 0.288 = 28.8%

## A 200 MW power station delivers 100 MW for 3 hours, 50 MW for 7 hours and remains shut down for rest of each day. It also remains shutdown for 50 per year. The energy supplied per year is

A 200 MW power station delivers 100 MW for 3 hours, 50 MW for 7 hours and remains shut down for rest of each day. It also remains shutdown for 50 per year. The energy supplied per year is:

- 18.48 *10^4 MWh
- 20.48 *10^4 MWh
- 22.48 *10^4 MWh
- 24.48 *10^4 MWh

Correct answer: 2. 20.48 *10^4 MWh

Solution:

Energy supplied for single working day = (100 * 3) + (50 * 7) = 650 MWh

——————–

Number of days for which station is operational = 365 – 50 = 315 days in year

——————–

Energy supplied/year = 650 * 315 = 20.48 * 10^4 MWh

## Economizers in thermal power stations are used to heat:

Economizers in thermal power stations are used to heat:

- Air
- Feed water
- Steam
- None of these

Correct answer: 2. Feed water

## If, power P available from hydro-scheme is given by formula P = 9.81 QH where Q is flow through turbine in litres/s and H is head in metres then P will be in units of

If, power P available from hydro-scheme is given by formula P = 9.81 QH where Q is flow through turbine in litres/s and H is head in metres then P will be in units of:

- W
- kWh
- kJ/s
- HP

Correct answer: 1. W