The chief advantage of Ward-Leonard system D.C. motor speed control is that is

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

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Related questions

In Ward-Leonard control the lower limit of speed is imposed by?

Last Answer : In Ward-Leonard control the lower limit of speed is imposed by residual magnetism of the generator.

The main disadvantage of the Ward-Leonard control method is?

Last Answer : The main disadvantage of the Ward-Leonard control method is high initial cost, high maintenance cost, low efficiency at light loads.

Ward-Leonard control is basically a?

Last Answer : Ward-Leonard control is basically a voltage control method.

The method of D.C. motor speed control shown in the illustration is known as _____________. EL-0101 A. Ward-Leonard B. Sperry-Rand C. Atlas-Copco D. Burmeister-Wain

Description : The method of D.C. motor speed control shown in the illustration is known as _____________. EL-0101 A. Ward-Leonard B. Sperry-Rand C. Atlas-Copco D. Burmeister-Wain

Last Answer : Answer: A

The basic type of D.C. motor speed control where a generator armature directly feeds the motor armature and the motor and generator fields are excited by a separate D.C. source is called ___________________. A. Burmeister-Wain B. Ward-Leonard C. Sperry-Rand D. Atlas-Copco

Description : The basic type of D.C. motor speed control where a generator armature directly feeds the motor armature and the motor and generator fields are excited by a separate D.C. source is called ___________________. A. Burmeister-Wain B. Ward-Leonard C. Sperry-Rand D. Atlas-Copco

Last Answer : Answer: B

is an open loop control system. (a) Ward Leonard control (b) Field controlled D.C. motor (c) Stroboscope (d) Metadyne

Description : is an open loop control system. (a) Ward Leonard control (b) Field controlled D.C. motor (c) Stroboscope (d) Metadyne

Last Answer : Ans: B

Speed control by Ward Leonard method gives uniform speed variation?

Last Answer : Speed control by Ward Leonard method gives uniform speed variation in both directions.

Ward - Leonard controlled DC drives are generally used for:

Last Answer : Ward - Leonard controlled DC drives are generally used for:  Heavy duty excavators

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

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.

With the increase in load on a d.c. shunt motor, speed of the motor

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.

A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated

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

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

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 

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

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.

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

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.

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

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.

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

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.

If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will?

Last Answer : If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will increase.

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Description : What does the city ward chief say ?

Last Answer : The city ward head is called the commissioner.

For constant torque drive which speed control method is preferred ?

Last Answer : For constant torque drive armature voltage control speed control method is preferred.

The advantage(s) of the method of D.C. motor speed control shown in the illustration is/are ______________. EL-0101 A. elimination of armature starting resistor losses B. elimination of speed instability with variable loads C. the ease of reversing motor direction D. all of the above

Description : The advantage(s) of the method of D.C. motor speed control shown in the illustration is/are ______________. EL-0101 A. elimination of armature starting resistor losses B. elimination of speed instability with variable loads C. the ease of reversing motor direction D. all of the above

Last Answer : Answer: D

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

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

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

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

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

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.

What will happen when a DC shunt motor is started with a 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.

A DC Motor develops a torque of 150 N-m. A 10 percent reduction in the field flux causes a 50 percent

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

A separately excited d.c. motor fed from single phase full converter with firing angle 60° runs at 1000 r.p.m.

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 

Last Answer : Ans =1500

If a d.c. motor is disconnected from the source and armature circuit is short circuited through a suitable

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

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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

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Under which of the following conditions is a DC motor provided with compensating winding

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

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A 200 V, 10 A motor could be rewound for 100 V, 20 A by using ..........

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.

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

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

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

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

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Description : A series motor is best suited for driving?

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

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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.

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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.

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

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

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Last Answer : series motor

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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.

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

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.

If the load current and flux of a d.c. motor are held constant and voltage applied ...

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.

Neglecting saturation, if current taken by a series motor is increased from 10 A to 12 A, the percentage increase...

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

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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.

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.

The shaft torque of a d.c. motor is less than its armature ...

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.

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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.

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

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

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

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.

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

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.

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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.

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

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.