Question

1-A facility Which instrument is useful for identifying uninsulated steam lines:

a- Tachymeter

b- Psychrometer

c- Infrared Camera

d- Bourdon Gauge

2- A new lighting system is installed to reduce energy use in a building What data is NOT needed to verify savings for this project :

a- Measurement of the CO2 level in the building .

b-Measurement of light levels .

c- Measurement of the power on the lighting circuit .

d- Measurement of the lighting system operating hours.

3-In a given facility you measure the incoming supply 3 phase voltage and you find the following voltages present, 236V , 231V ,227V imbalance.What impact is this likely to have on the motor load in the installation?

a- Increase motor losses by approx. 7%

b- Increase motor losses by apprax. 15%

c- Reduce motor losses by approx. 7%

d - Reduce motor losses by approx. 15%

4- ACE industries presently has a 11 kW exhaust fan motor that exhaust air from a production area. With the original ventilation flow rate, the fan motor was fully loaded. They have determined the volume flow rate of ventilation can be reduiced by 30% and still satisfy ventilation regulations. If the fan efficiency remains the same, what new minimum motor capacity is required to drive the system with reduced flow rate? Select the best choice from the motor capacities listed below the motor service factor is 1 ?

a- 3 kW

b- 4 kW

c- 5.5 kW

d- 7.5 KW

Answer 1

1. Option c - Infrared camera.

Explanation: Tachymeter is used to mesure speed based on time tavelled over a fixed distance. Whereas, Pshycrometer is used for measuring humidity of air. Again, Bourdon gauge is a mechanical device used for measuring pressure. But, Infrared camera is used for detecting uninsulated stream lines.

2. Option A- Measurement of CO2 level in building

Explanation: Measurements of light levels sets up the base for comparison with other type of lighting sysrtems for energy comparison. Measurement of power of lighting circuit is very necessery as Energy = (Power x time). . Measurement of lighting system operating time is required to calculate Energy as , Energy = (Power x time).

3. Option A- Increase motor loss by approx 7%

Explanation: Unbalance is supply voltage will always cause increase in motor losses as extra losses will be generated by higher frequency components of currents( if we do fourier analysis of unbalanced supply, we can understand better.). As loss is proportional to (Supply voltage)² . So, calculation for individual phases gives approx increase of 7% loss.

4. Option d- 7.5 kW.

Explanation: As, we can say that, power rating of a motor in exhaust fan is approxmately proportional to volume flow rate of air in full load. hence, 30% reduction in volume flow rate implies approx 30% reduction in motor rating if we want to run it in full load. So, new motor rating = 11 x (1 - 0.3) = 7.7 kW. So the closest answar is 7.5kW