# The Ta/Ia graph of a d.c. series motor is a?

The Ta/Ia graph of a d.c. series motor is a?

The Ta/Ia graph of a d.c. series motor is a parabola upto full-load and a straight line at overloads.

## Related questions

Description : A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to  (A) 0.75 p.u (B) 0.5 p.u (C) 0.25 p.u (D) 0.125 p.u

Last Answer : A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to 0.5 p.u

Description : The d.c. series motor should never be switched on at no load because?

Last Answer : The d.c. series motor should never be switched on at no load because the speed becomes dangerously high.

Description : A series motor is best suited for driving?

Last Answer : A series motor is best suited for driving cranes and hoists.

Description : Unlike a shunt motor, it is difficult for a series motor to stall under heavy loading because?

Last Answer : Unlike a shunt motor, it is difficult for a series motor to stall under heavy loading because it develops high overload torque.

Description : As compared to shunt and compound motors, series motor has the highest torque because of its comparatively .......... at the start.

Last Answer : As compared to shunt and compound motors, series motor has the highest torque because of its comparatively stronger series field at the start.

Description : Neglecting saturation, if current taken by a series motor is increased from 10 A to 12 A, the percentage increase in its torque is ........ percent

Last Answer : Neglecting saturation, if current taken by a series motor is increased from 10 A to 12 A, the percentage increase in its torque is 44 percent

Description : How much does a Massey Ferguson 1500 series tractor sell for in Des Moines, IA?

Last Answer : The average price of a Massey Ferguson 1500 series tractor may run you anywhere from \$18,000 to \$33,000. The price depends on the model of tractor you choose to purchase.

Description : The muscle spindles: a. are extrafusal fibres b. are innervated by type Ia and II fibres c. received motor innervation from the gamma fibres. d. respond to tension in the muscle

Last Answer : are innervated by type Ia and II fibres

Description : When running under no-load condition and with over excitation, armature current Ia drawn by a synchronous motor

Last Answer : When running under no-load condition and with over excitation, armature current Ia drawn by a synchronous motor Leads the applied voltage

Last Answer : During rheostat braking of D.C. series motors motor is run as a generator.

Description : Explain the necessity of starter for D.C. motor. State various types of D.C. motor starter.

Last Answer : Necessity of Starter for D.C. Motor: Armature current is given by equation Ia = (V−Eb)/Ra i) If the motor is at standstill or rest, back emf Eb is zero (as Eb= ZNP/(60A), at start speed N ... . Types of D.C. motor starters: i) Two point starter ii)Three point starter iii) Four point starter

Description : State at least one function and the material used for the following parts of DC Motor.

Last Answer : Part Function Material Yoke -Provides mechanical support for poles -Acts as protecting cover for machine -Provides path for magnetic flux Cast Iron OR Cast Steel Field Winding - ... Pole core  Provides mechanical support to field winding. Cast Iron OR Cast Steel

Description : Why shouldn’t a DC shunt motor start on the heavy load setting?

Last Answer : A series motor never started at no load and a shunt motor is never started at on load.

Description : What will happen when a DC shunt motor is started with a load?

Last Answer : Starting current will be very high so motor will take more current from supply. It may damage the armature winding.

Description : Why does the speed of a DC shunt motor decrease as the load increases?

Last Answer : Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease.

Description :  A DC Motor develops a torque of 150 N-m. A 10 percent reduction in the field flux causes a 50 percent increase in armature current. The new value of torque is: A) 102.5 N-m B) 202.5 N-m C) 172.5 N-m D) 232.5 N-m

Last Answer : T1=KIf,T2=K1.5I*0.9f T1=150Nm.  T2=T1*1.5*0.9=150*1.35=202.5Nm

Description : A separately excited d.c. motor fed from single phase full converter with firing angle 60° runs at 1000 r.p.m. If motor is connected to single phase semiconverter with the same firing angle of 60°, it would run at (a) 2000 rpm (b) 1850 rpm (c) 1500 rpm (d) 1000 rpm

Description : If a d.c. motor is disconnected from the source and armature circuit is short circuited through a suitable resistance, the process is called (a) regenerative breaking (b) rheostatic breaking (c) dynamic breaking (d) no breaking is possible

Last Answer : b) rheostatic breaking Because rheostat is connected to chang the power dissipated into heat.

Description : With the increase in load on a d.c. shunt motor, speed of the motor (a) increases proportionately (b) remains constant (c) increase slightly (d) reduces slightly

Last Answer : With the increase in load on a d.c. shunt motor, speed of the motor reduces slightly.

Description : To conduct load test on a dc shunt motor, it is coupled to a generator which is identical to the motor. The field of the generator is also connected to the same supply source as the motor. The armature of generator is ... value of this load resistance is  (A) 1.0 (B) 0.98 (C) 0.96 (D) 0.94

Last Answer : To conduct load test on a dc shunt motor, it is coupled to a generator which is identical to the motor. The field of the generator is also connected to the same supply source as the motor. ... obtain rated armature current in both motor and generator. The p.u value of this load resistance is 0.96

Description : The dc motor, which can provide zero speed regulation at full load without any controller is  (A) series (B) shunt (C) cumulative compound (D) differential compound

Last Answer : The dc motor, which can provide zero speed regulation at full load without any controller is shunt

Description : The chief advantage of Ward-Leonard system D.C. motor speed control is that is  1. Can be used even for small motors 2. has high overall efficiency at all speeds 3. Gives smooth, sensitive and wide speed control 4. Uses a flywheel to reduce fluctuations in power demand

Last Answer : The chief advantage of Ward-Leonard system D.C. motor speed control is that is Gives smooth, sensitive and wide speed control

Description : Under which of the following conditions is a DC motor provided with compensating winding used?  1. Wide range of speed control above normal  2. Wide range of steady load variation with no speed control  3. Wide range of rapid variation in ...  (a) 1, 2 and 3 (b) 2 and 3 (c) 1 and 2 (d) 1 and 3

Last Answer : Under which of the following conditions is a DC motor provided with compensating winding used?  1. Wide range of speed control above normal  2. Wide range of steady load variation with no speed control  3. Wide range of rapid variation ...  (a) 1, 2 and 3 (b) 2 and 3 (c) 1 and 2 (d) 1 and 3

Description : A 200 V, 10 A motor could be rewound for 100 V, 20 A by using .......... as many turns per coil of wire, having .......... the cross-sectional area.

Last Answer : A 200 V, 10 A motor could be rewound for 100 V, 20 A by using half, as many turns per coil of wire, having twice the cross-sectional area.

Description : A shunt d.c. motor works on a.c. mains?

Last Answer : A shunt d.c. motor works on a.c. mains unsatisfactorily.

Description : A 220 V shunt motor develops a torque of 54 N-m at armature current of 10 A. The torque produced when the armature current is 20 A, is?

Last Answer : Armature torque, Ta=PØZIa/2πA So Ta1/Ta2=Ia1/Ia2 Ta2=Ta1*Ia2/Ia1        =54*20/10         =108

Description : When load is removed, .......... motor will run at the highest speed.

Last Answer : When load is removed, series motor will run at the highest speed.

Description : Between no-load and full-load, .......... motor develops the least torque.

Description : A d.c. shunt motor is found suitable to drive fans because they require?

Last Answer : A d.c. shunt motor is found suitable to drive fans because they require small torque at start up, large torque at high speeds.

Description : If the field circuit of a loaded shunt motor is suddenly opened?

Last Answer : If the field circuit of a loaded shunt motor is suddenly opened circuit breaker or fuse will open the circuit before too much damage is done to the motor.

Description : If the pole flux of a d.c. motor approaches zero, its speed will?

Last Answer : If the pole flux of a d.c. motor approaches zero, its speed will approach infinity.

Description : If the load current and flux of a d.c. motor are held constant and voltage applied across its armature is increased by 10 per cent, its speed will?

Last Answer : If the load current and flux of a d.c. motor are held constant and voltage applied across its armature is increased by 10 percent, its speed will increase by about 10 percent.

Description : If load on a d.c. shunt motor is increased, its speed is decreased due primarily to?

Last Answer : If load on a d.c. shunt motor is increased, its speed is decreased due primarily to decrease in back e.m.f.

Description : A d.c. motor develops a torque of 200 N-m at 25 rps. At 20 rps it will develop a torque of .......... N-m.

Last Answer : A d.c. motor develops a torque of 200 N-m at 25 rps. At 20 rps it will develop a torque of 200 N-m.

Description : The shaft torque of a d.c. motor is less than its armature torque because of .......... losses.

Last Answer : The shaft torque of a d.c. motor is less than its armature torque because of rotational losses.

Description : The current drawn by a 120 - V d.c. motor of armature resistance 0.5 Ω and back e.m.f. 110 V is .......... ampere.

Last Answer : The current drawn by a 120 - V d.c. motor of armature resistance 0.5 Ω and back e.m.f. 110 V is 20 ampere.

Description : Under constant load conditions, the speed of a d.c. motor is affected by?

Last Answer : Under constant load conditions, the speed of a d.c. motor is affected by field flux.

Description : In a d.c. motor, the mechanical output power actually comes from?

Last Answer : In a d.c. motor, the mechanical output power actually comes from electrical input power.

Description : A d.c. motor can be looked upon as d.c. generator with the power flow?

Last Answer : A d.c. motor can be looked upon as d.c. generator with the power flow reversed.

Description : The induced e.m.f. in the armature conductors of a d.c. motor is?

Last Answer : The induced e.m.f. in the armature conductors of a d.c. motor is sinusoidal.

Description : The mechanical power developed by the armature of a d.c. motor is equal to?

Last Answer : The mechanical power developed by the armature of a d.c. motor is equal to armature current multiplied by back e.m.f.

Description : The Eb/V ratio of a d.c. motor is an indication of its?

Last Answer : The Eb/V ratio of a d.c. motor is an indication of its efficiency.

Description : The normal value of the armature resistance of a d.c. motor is?

Last Answer : The normal value of the armature resistance of a d.c. motor is 0.5.

Description : The counter e.m.f. of a d.c. motor?

Last Answer : The counter e.m.f. of a d.c. motor helps in energy conversion.

Description : In a d.c. motor, unidirectional torque is produced with the help of

Last Answer : Commutator provides unidirectional torque and pulsating dc

Description : In DC motor iron losses are occurred in?

Last Answer : In DC motor iron losses are occurred in the armature.

Last Answer : Series motor has got maximum self relieving property.

Description : D.C. motor is to a drive a load which is almost nil for certain part of the load cycle and peak value for short duration. We will select the?

Last Answer : D.C. motor is to a drive a load which is almost nil for certain part of the load cycle and peak value for short duration. We will select the compound motor.

Description : D.C. motor is to drive a load which has certain minimum value for most of the time and some peak value for short duration. We will select the?

Last Answer : DC motor mostly preferred is DC series motor becaus the load is continuous for a long time

Last Answer : If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens this will make armature to take heavy current, possibly burning it.