Objective Questions on AC/DC Motor Drives for Electrician Trade
| Sr. No. | Questions with options |
| 1 | Which control system consumes very low power for motion control in AC and DC motors?
(a) Field control (b) Drives control (c) Voltage control (d) Armature control Ans – (b) |
| 2 | Which drive is classified according to mode of operation?
(a) Group drive (b) Manual drive (c) Individual drive (d) Continuous duty drive Ans – (d) |
| 3 | What is electric drive?
(a) A device used as prime mover for generator (b) A device converts A.C to D.C supply (c) An electro mechanical device for controlling motor (d) A machine converts mechanical energy into electrical Ans- (c) |
| 4 | What is the full form of B.O.P in D.C drive?
(a) Bridge operation panel (b) Basic operational panel (c) Basic operation programme (d) Bridge operator programme Ans –(b) |
| 5 | Which is the classification of drive according to dynamics and transients?
(a) Short time duty drive (b) Intermittent duty drive (c) Automatic control drive (d) Variable position control drive Ans – (d) |
| 6 | What is the function of power controller in drive circuits?
(a) It sounds an alarm in no load conditions (b) It detects the overloading condition of motor (c) It reduce motor current during transient (d) It maintain the torque at low voltage conditions Ans – (b) |
| 7 | Why it is necessary to keep V/F ratio constant in a drive?
(a) Keep the stator flux maximum (b) Maintain the rotor current minimum (c) Maintain the speed of motor constant (d) Maintain the rated torque at all speeds Ans – (d) |
| 8 | Which power modulator used in the electric drive system?
(a) Cyclo converters (b) Frequency multiplier (c) Phase sequence indicator (d) Servo controlled voltage stabilizer Ans – (a) |
| 9 | Which type of sensing unit employed in drive system?
(a) Opto coupler (b) Speed sensing (c) Photo voltaic cell (d) Resistance temperature detector Ans – (b) |
| 10 | Which type of machine in industries is provided with multi motor electric drive?
(a) Rolling machine (b) Air compressor (c) Shearing machine (d) Heavy duty electric drilling machine Ans – (a) |
| 11 | Which control system is used for eddy current drives?
(a) Slip controller (b) Rectifier controller (c) AC voltage controller (d) DC chopper controller Ans – (a) |
| 12 | What is the purpose of JOG key in control panel of D.C drive?
(a) Stop the motor (b) Restart the motor (c) Inching operation (d) Reverse the direction of motor Ans – (c) |
| 13 | What is the purpose of LCD on basic operator panel in D.C drive?
(a) Indicate the fault (b) Display the speed (c) Monitor the parameter (d) Display availability of supply Ans – (c) |
| 14 | What is the reason of using shielded cable for connecting low level signal circuits in DC drives?
(a) Easy for connection (b) Good appearance (c) Protects from mechanical injuries (d) Eliminates the electrical interference Ans – (d) |
| 15 | Which device controls the speed of A.C motor in A.C drive?
(a) Field supply unit (b) COOMS technology box (c) Speed feedback technology box (d) Microprocessor based electronic dvice Ans – (d) |
| 16 | What is the main use of A.C drive?
(a) High starting torque (b) Group drive motors (c) Control stepless speed in motors (d) Interlocking system in industries Ans – (c) |
| 17 | What is the function of IGBT in AC drive?
(a) Smoothening incoming A.C supply (b) Controls the power delivered to the motor (c) Stabilize the output voltage from the rectifier (d) Converts incoming A.C power into D.C power output Ans- (b) |
| 18 | Why the A.C drives are better suited for high speed operation?
(a) High starting torque (b) Robust in construction (c) Having lighter gauge winding (d) No brushes and commutation Ans – (d) |
| 19 | What is the advantage of AC drive compared to DC drive?
(a) Requires less space (b) Installation and running cost is less (c) Fast response and wide speed range of control (d) Power circuit and control circuits are simple Ans – (b) |
| 20 | Which is the application of single quadrant loads operating in first quadrant in drives?
(a) Hoists (b) Elevators (c) Conveyors (d) Centrifugal pumps Ans – (d) |
| Published On – 11th June 2022 | |
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