Recent questions tagged variable

Description : With sketch, justify use of Variable Geometry Turbocharger as compared to fixed geometry turbocharger. 

Last Answer : Variable Turbine Geometry technology is the next generation in turbocharger technology where the turbo uses variable vanes to control exhaust flow against the turbine blades. The problem with the ... The angles of the vanes vary throughout the engine RPM range to optimize turbine behaviour.

Description : List variable flow meter. 

Last Answer : 1. Variable area : Rotameter 2. Variable head : a) Venturi b) Orifice c) Pitot tube d) Nozzle

Description : Define resistor and draw symbol of variable resistor.

Last Answer : Resistor: A resistor is an electrical component that limits or regulates the flow of electrical current in an electronic circuit. Symbol of variable resistor:   

Description : Compare variable head flow meter with variable area flow meter.

Last Answer : Parameter Variable head flowmeter Variable area flowmeter Working principle Restriction or obstacle is placed in the path of flow to create a differential Pressure. The pressure ... viscous fluid slurries and dirty fluids. In laboratories and testing and production lines.

Description : Compare variable reluctance and permanent magnet motors.

Last Answer : Variable reluctance Motor  Permanent magnet motors   The rotor is not magnetised The rotor is magnetised  High torque to inertia ratio  Low torque to inertia ratio  ... rotor has salient pole construction The rotor has mostly smooth cylindrical type of construction. 

Description : Explain following techniques related to energy conservation in transmission and distribution system. (i) By balancing phase currents (ii) Variable technical losses (I2R losses).

Last Answer : (i) Balancing Phase currents: Proper (healthy balanced) three phase loads always draw equal currents in all lines but single phase loads in the 3 phase 4 wire system or loads connected between two ... . 11) Minimize I2R losses. 12) Balance the load currents. 13) Regulate the system voltages.

Description : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque  (1) Decreases (2) Increases (3) Remains constant (4) None of the above

Last Answer : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque Increases 

Description : In a self-controlled synchronous motor fed from a variable frequency inverter  (1) the rotor poles invariably have damper windings  (2) there are stability problems  (3) the speed of the rotor decides stator frequency  (4) the frequency of the stator decides the rotor speed

Last Answer : 2

Description : With the knowledge of the state variable representation of a plant the transfer function of the plant 

Last Answer : With the knowledge of the state variable representation of a plant the transfer function of the plant can be determined completely

Last Answer : In variable speed motor a weaker commutating field is needed at low speed than at high speed.

Description : Advantages of Variable Frequency Drive (VFD)

Last Answer : Advantages of Variable Frequency Drive (VFD)