31. A pressure transmitter is wired directly to a VFD and a DDC Controller from a BAS system only starts and stops the VFD. Which of the following is the correct connection?
A) An AO on the Controller is wired to an AI of the VFD.
B) An AI on the Controller is wired to an AO of the VFD.
C) A DI on the Controller is wired to a DO of the VFD.
D) An AI on the Controller is wired to an DO of the VFD.
E) A DO on the Controller is wired to a DI of the VFD.
Ans: E
32. A pressure transmitter (4-20mA) is needed to monitor the feedback going to a VFD, which is programmed for Closed Loop. To which of the following VFD control wire connections should the transmitter be attached for proper operation?
A. Analog Input
B. Digital Input
C. Analog/Digital Output
D. Relay Output
E. Both C and D are correct
Ans: A
33. A light is used to indicate when the VFD goes into an alarm condition. To which of the following VFD control wire connections should a 120Vac light be attached.
A. Analog Input
B. Digital Input
C. Analog/Digital Output
D. Relay Output
E. Both C and D are correct
Ans: D
34. Three VFDs are operating via Serial Communications with a Local Area DDC Controller. How many wire connections are needed on the VFD for serial communications?
A. 2 wire
B. 4 wire
C. 9 wire
D. 10 wire
E. It depends on how much information is desired between the VFDs and DDC Controller.
Ans: A
35. When discussing if a drive is 6,12 or 18 Pulse, which part of the drive is being discussed?
A. Inverter
B. DC Link
C. Rectifier
D. RFI Filter
E. Transmitter
Ans: C
36. Banks of large capacitors are the most prominent in which of the following parts of a drive?
A. Inverter
B. DC Link
C. Rectifier
D. RFI Filter
E. Transmitter
Ans: B
37. The main function of which of the following parts of an VFD is to change a high DC voltage into a pulsed AC voltage.
A. Inverter
B. DC Link
C. Rectifier
D. RFI Filter
E. Transmitter
Ans: A
38. If 480Vac is the incoming power to the VFD, which of the following is the expected voltage at the DC Link?
A. 240Vdc
B. 312Vdc
C. 480Vdc
D. 648Vdc
E. 800Vdc
Ans: D
39. IGBTs are found in which part of the drive?
A. Inverter
B. DC Link
C. Rectifier
D. RFI Filter
E. Transmitter
Ans: A
40. What type of application curve must be used inside a VFD to operate these Cooling Tower Fans correctly?
A) Constant Torque
B) Variable Torque
C) Constant Power
D) Variable Power
Ans: B
A) An AO on the Controller is wired to an AI of the VFD.
B) An AI on the Controller is wired to an AO of the VFD.
C) A DI on the Controller is wired to a DO of the VFD.
D) An AI on the Controller is wired to an DO of the VFD.
E) A DO on the Controller is wired to a DI of the VFD.
Ans: E
32. A pressure transmitter (4-20mA) is needed to monitor the feedback going to a VFD, which is programmed for Closed Loop. To which of the following VFD control wire connections should the transmitter be attached for proper operation?
A. Analog Input
B. Digital Input
C. Analog/Digital Output
D. Relay Output
E. Both C and D are correct
Ans: A
33. A light is used to indicate when the VFD goes into an alarm condition. To which of the following VFD control wire connections should a 120Vac light be attached.
A. Analog Input
B. Digital Input
C. Analog/Digital Output
D. Relay Output
E. Both C and D are correct
Ans: D
34. Three VFDs are operating via Serial Communications with a Local Area DDC Controller. How many wire connections are needed on the VFD for serial communications?
A. 2 wire
B. 4 wire
C. 9 wire
D. 10 wire
E. It depends on how much information is desired between the VFDs and DDC Controller.
Ans: A
35. When discussing if a drive is 6,12 or 18 Pulse, which part of the drive is being discussed?
A. Inverter
B. DC Link
C. Rectifier
D. RFI Filter
E. Transmitter
Ans: C
36. Banks of large capacitors are the most prominent in which of the following parts of a drive?
A. Inverter
B. DC Link
C. Rectifier
D. RFI Filter
E. Transmitter
Ans: B
37. The main function of which of the following parts of an VFD is to change a high DC voltage into a pulsed AC voltage.
A. Inverter
B. DC Link
C. Rectifier
D. RFI Filter
E. Transmitter
Ans: A
38. If 480Vac is the incoming power to the VFD, which of the following is the expected voltage at the DC Link?
A. 240Vdc
B. 312Vdc
C. 480Vdc
D. 648Vdc
E. 800Vdc
Ans: D
39. IGBTs are found in which part of the drive?
A. Inverter
B. DC Link
C. Rectifier
D. RFI Filter
E. Transmitter
Ans: A
40. What type of application curve must be used inside a VFD to operate these Cooling Tower Fans correctly?
A) Constant Torque
B) Variable Torque
C) Constant Power
D) Variable Power
Ans: B
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