A. Frequency of magnetic reversals
B. Maximum value of flux density
C. Volume and grade of iron
D. Rate of flow of ventilating air
Correct Answer: Rate of flow of ventilating air ✔
Last Updated: July 02, 2018
Related MCQs
- Regenerative method of braking is based on that__________?
- The main disadvantage of the Ward-Leonard control method is__________?
- In Ward-Leonard control the lower limit of speed is imposed by________?
- For constant torque drive which speed control method is preferred ?
- Ward-Leonard control is basically a__________?
- Which motor should not be started on no-load ?
- Which of the following motors is most suitable for signalling devices and many kinds of timers ?
- Which of the following motors is usually used in house-hold refrigerators ?
- Why are the D.C. motors preferred for traction applications ?
- If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will_________?
- Which of the following motors one will choose to drive the rotary compressor ?
- If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking?
- If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor__________?
- The armature voltage control of D.C. motor provides__________?
- The plugging gives the__________?
- For a D.C. shunt motor if the excitation is changed__________?
- Which motor has the poorest speed control?
- If I2 be the armature current, then speed of a D.C. shunt motor is__________?
- The speed of a D.C. shunt motor can be increased by__________?
- As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit__________?
- The armature voltage control of D.C. motor provides__________?
- The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is__________?
- Usually wide and sensitive speed control is desired in case of__________?
- Which of the following method of speed control of D.C. machine will offer minimum efficiency ?
- The armature torque of the D.C. shunt motor is proportional to__________?
- As -the load is increased the speed of D.C. shunt motor will__________?
- Which of the following motor has the poorest speed regulation ?
- Buses, trains, trolleys, hoists, cranes require high starting torque and therefore make use of__________?
- In a differentially compounded D.C. motor, if shunt field suddenly opens__________?
- Following motor is used where high starting torque and wide speed range control is required?
- Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be__________?
- Speed control by Ward Leonard method gives uniform speed variation__________?
- Sparking, is discouraged in a D.C. motor because__________?
- Three point starter can be used for__________?
- Which D.C. motor is generally preferred for cranes and hoists ?
- In D.C. machines the residual magnetism is of the order of__________?
- For which of the following applications a D.C. motor is preferred over an A.C. motor ?
- The condition for maximum power in case of D.C. motor is__________?
- The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is__________?
- Which one of the following is not the function of pole shoes in a D.C. machine ?
- If the supply voltage for a D.C. motor is increased, which of the following will decrease ?
- Which of the following motor is preferred for operation in highly explosive atmosphere ?
- Sparking at the commutator of a D.C. motor may result in__________?
- In case of conductively compensated D.C. series motors, the compensating winding is provided__________?
- For the same H.P. rating and full load speed, following motor has poor starting torque__________?
- D.C. series motors are used__________?
- If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens__________?
- Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads?
- Which D.C. motor has got maximum self loading property?
- The power mentioned on the name plate of an electric motor indicates__________?
- The current drawn by the armature of D.C. motor is directly proportional to__________?