Practice Test GeeksCEM - Certified Energy Manager Practice Test
← All CEM Flashcard Decks

Certified Energy Manager Motors and HVAC Flashcards

7 cards from real CEM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Certified Energy Manager Motors and HVAC flashcards as text

  1. Which motor protection device guards against single-phasing in a three-phase motor?

    Answer: Thermal overload relay with phase-loss sensitivity

    A thermal overload relay with phase-loss sensitivity detects the current imbalance caused by single-phasing and trips before winding damage occurs.

  2. In a chilled water system, what is the benefit of increasing chilled water delta-T from 10°F to 14°F at the same cooling load?

    Answer: Reduced chilled water flow rate and pump energy

    A higher chilled water delta-T allows the same cooling load to be met with less flow, reducing pump energy consumption.

  3. What is the NEMA efficiency designation for a motor that meets or exceeds NEMA Premium efficiency levels?

    Answer: NEMA MG1 Table 12-12

    NEMA Premium efficiency motors meet or exceed the efficiency levels defined in NEMA MG1 Table 12-12.

  4. An economizer on an air handling unit uses outdoor air for free cooling when:

    Answer: Outdoor dry-bulb or enthalpy is below the return air condition

    An economizer brings in outdoor air when it is cooler (or has lower enthalpy) than return air, allowing mechanical cooling to be reduced or eliminated.

  5. Which parameter is used to evaluate the part-load efficiency of a chiller under real-world mixed operating conditions?

    Answer: Integrated Part Load Value (IPLV)

    IPLV (Integrated Part Load Value) is a weighted average efficiency metric that accounts for chiller performance at 25%, 50%, 75%, and 100% load.

  6. What is the primary energy penalty associated with operating a motor at loads well below its rated capacity?

    Answer: Reduced motor efficiency and power factor

    Motors operating significantly below rated load have reduced efficiency and power factor, increasing energy losses per unit of useful work.

  7. In a heat pump, the coefficient of performance (COP) in heating mode is related to COP in cooling mode by:

    Answer: COP_heating = COP_cooling + 1

    COP_heating = COP_cooling + 1 because the heating output equals the cooling capacity plus the compressor work input.