Maricopa Community Colleges  HVA140AB   19932-20086 
Official Course Description: MCCCD Approval: 07/22/08
HVA140AB 19932-20086 LEC 1 Credit(s) 1 Period(s)
Alternating Current Variable Frequency Drives
Principles and operation of frequency-controlled AC motor drives, including current source inverters (CSI), variable voltage inverters (VVI) and pulse width modulated inverters (PWM). Heating, ventilation, and air conditioning (HVAC) applications along with energy savings, motor-pump sizing, and torque-load calculations.
Prerequisites: None.
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MCCCD Official Course Competencies:
 
HVA140AB   19932-20086 Alternating Current Variable Frequency Drives
1. Describe the construction and operation of AC induction motors. (I)
2. Explain the effect of frequency on the speed of an AC motor. (II)
3. Explain the effect of frequency on the torque output of an AC motor. (III)
4. Describe the construction and operation of current source inverters (CSI). (IV)
5. Describe the construction and operation of variable voltage inverters (VVI). (V)
6. Describe the construction and operation of pulse width modulated inverters (PWM). (VI)
7. Determine horse power requirements for various sized pump applications. (VII)
8. Determine energy savings with variable frequency drives versus other standard drives. (VIII)
9. Describe adjustments on operating variable frequency drive systems. (IX)
10. Explain the application of variable speed drives to heating, ventilating, and air conditioning systems. (IX)
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MCCCD Official Course Outline:
 
HVA140AB   19932-20086 Alternating Current Variable Frequency Drives
    I. AC Induction Motors
        A. Basic construction
        B. Induction from field to rotor
        C. Rotating magnetic field in stator
      II. Frequency and Speed
          A. Slip speed
          B. Number of pole pairs
          C. Variance of frequency
        III. Frequency and Torque
            A. Air gap flux density
            B. Impedance variance
            C. Voltage variation
            D. Frequency/voltage relationship
          IV. Current Source Inverters
              A. Description
              B. Operational characteristics
              C. Advantages versus disadvantages
            V. Variable Voltage Inverters
                A. Description
                B. Operational characteristics
                C. Advantages versus disadvantages
              VI. Pulse Width Modulated Inverters
                  A. Description
                  B. Operational characteristics
                  C. Advantages versus disadvantages
                VII. Horsepower Requirements
                    A. Duty cycle
                    B. Flow formula
                    C. Weighted horsepower
                  VIII. Energy Savings
                      A. Outlet damper versus variable speed
                      B. Pressure requirements
                      C. Throttle valves
                      D. Mechanical variable speed
                      E. Cycling system
                    IX. Adjustments/Applications - HVAC
                        A. Air-handling fans
                        B. Refrigerant compressors
                        C. Heating systems
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