CEM Compressed Air and Power Systems 2

Question 1

Power factor correction in industrial facilities is important because low power factor:

Accepted Answer

Increases current draw for the same real power load, increasing I²R losses and potentially incurring utility penalties

Answer

Low power factor means more current flows for the same real (kW) load, increasing resistive losses in conductors and transformers and often triggering utility demand or power factor penalty charges.

Question 2

The nameplate efficiency of an electric motor represents its efficiency at:

Accepted Answer

100% of rated full load under standard test conditions

Answer

Motor nameplate efficiency is measured at full rated load per NEMA standards; actual efficiency varies with load and is typically lower at very light loads.

Question 3

NEMA Premium efficiency motors save energy compared to standard efficiency motors primarily because they have:

Accepted Answer

Reduced electrical (I²R) and core (iron) losses through better materials and design

Answer

Premium efficiency motors use higher grades of silicon steel, more copper in windings, closer tolerances, and improved designs to reduce core and copper losses, achieving 2-8% better efficiency than standard motors.

Question 4

Demand response programs allow large energy users to save money by:

Accepted Answer

Curtailing or shifting electricity use during grid peak events in exchange for utility payments or rate credits

Answer

In demand response programs, facilities agree to reduce load when called upon by utilities or grid operators during high-demand events, receiving payments or bill credits in return.

Question 5

Transformer losses consist of two components. Which component varies with load?

Accepted Answer

Copper (load) losses, which vary with the square of the load current

Answer

Copper losses (I²R heating in windings) vary with the square of load current; core losses (hysteresis and eddy currents in iron) are essentially constant whenever the transformer is energized.

CEM - Certified Energy Manager Practice Test

CEM - Certified Energy Manager Practice Test

CEM Compressed Air and Power Systems 2