menu search
person
thumb_up_alt 0 like thumb_down_alt 0 dislike
105 views

1 Answer

If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses.

thumb_up_alt 0 like thumb_down_alt 0 dislike
← Prev Question Next Question →

Related questions

Description :

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.

thumb_up_alt 0 like thumb_down_alt 0 dislike
112 views 1 answer
Description :

Answer :

In a differentially compounded D.C. motor, if shunt field suddenly opens the motor will first stop and then run in opposite direction as series motor.

thumb_up_alt 0 like thumb_down_alt 0 dislike
73 views 1 answer
Description :

Answer :

If the field of a D.C. shunt motor gets opened while motor is running the motor will attain dangerously high speed.

thumb_up_alt 0 like thumb_down_alt 0 dislike
108 views 1 answer
Description :

Answer :

The armature may burn if the back e.m.f. of a D.C. motor vanishes suddenly.

thumb_up_alt 0 like thumb_down_alt 0 dislike
401 views 1 answer
Description :

A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be

Answer :

A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be 474 V

thumb_up_alt 0 like thumb_down_alt 0 dislike
319 views 1 answer
Description :

Answer :

The speed of a D.C. shunt motor more than its full-load speed can be obtained by decreasing the field current.

thumb_up_alt 0 like thumb_down_alt 0 dislike
101 views 1 answer
Description :

Answer :

As the load is increased the speed of D.C. shunt motor will reduce slightly.

thumb_up_alt 0 like thumb_down_alt 0 dislike
116 views 1 answer
Description :

Answer :

For a D.C. shunt motor if the excitation is changed torque will change but power will remain constant.

thumb_up_alt 0 like thumb_down_alt 0 dislike
138 views 1 answer
Description :

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?

Answer :

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 a resistance is connected in series with armature.

thumb_up_alt 0 like thumb_down_alt 0 dislike
133 views 1 answer
Description :

A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is

Answer :

A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is 36 Ohm

thumb_up_alt 0 like thumb_down_alt 0 dislike
192 views 1 answer
Description :

If field current is decreased in shunt dc motor, the speed of the motor (a) remains same. (b) increases. (c) decreases. (d) none of the above.

Answer :

increases

thumb_up_alt 0 like thumb_down_alt 0 dislike
2.0k views 4 answers
Description :

Answer :

The speed of a D.C. shunt motor can be increased by increasing the resistance in field circuit.

thumb_up_alt 0 like thumb_down_alt 0 dislike
98 views 1 answer
Description :

Answer :

In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be more than full-load current.

thumb_up_alt 0 like thumb_down_alt 0 dislike
215 views 1 answer
Description :

Answer :

In a D.C. shunt motor, speed is independent of armature current.

thumb_up_alt 0 like thumb_down_alt 0 dislike
68 views 1 answer
Description :

Answer :

The armature torque of the D.C. shunt motor is proportional to armature current.

thumb_up_alt 0 like thumb_down_alt 0 dislike
104 views 1 answer
Description :

In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is :

Answer :

In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is : 0.075

thumb_up_alt 0 like thumb_down_alt 0 dislike
82 views 1 answer
Description :

The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ (A) directly proportional to α and Φ (B) inversely proportional to α and Φ (C) directly proportional to α and inversely proportional to Φ (D) directly proportional to Φ and inversely proportional to α

Answer :

The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ directly proportional to α and inversely proportional to Φ

thumb_up_alt 0 like thumb_down_alt 0 dislike
128 views 1 answer
Description :

Why dc series motor should not be started at no load?

thumb_up_alt 0 like thumb_down_alt 0 dislike
605 views 0 answers
Description :

Answer :

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

thumb_up_alt 0 like thumb_down_alt 0 dislike
122 views 1 answer
Description :

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

Answer :

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

thumb_up_alt 0 like thumb_down_alt 0 dislike
2.6k views 1 answer
Description :

Answer :

At the instant of starting when a D.C. motor is put on supply, it behaves like a low resistance circuit.

thumb_up_alt 0 like thumb_down_alt 0 dislike
74 views 1 answer
Description :

Answer :

Sparking at the commutator of a D.C. motor may result in damage to commutator segments, damage to commutator insulation, increased power consumption.

thumb_up_alt 0 like thumb_down_alt 0 dislike
141 views 1 answer
Description :

Answer :

By looking at Commutator part of the motor, it can be easily confirmed that a particular motor is D.C. motor.

thumb_up_alt 0 like thumb_down_alt 0 dislike
91 views 1 answer
Description :

Answer :

If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor is to be derated by a factor recommended by manufacturer and select the next higher H.P. motor.

thumb_up_alt 0 like thumb_down_alt 0 dislike
79 views 1 answer
Description :

Answer :

In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to 25% of the previous value.

thumb_up_alt 0 like thumb_down_alt 0 dislike
164 views 1 answer
Description :

Answer :

If a D.C. motor is connected across the A.C. supply it will burn due to heat produced in the field winding by eddy currents.

thumb_up_alt 0 like thumb_down_alt 0 dislike
78 views 1 answer
Description :

Answer :

If a D.C. series motor is operated on A.C. supply, it will spark excessively, have poor efficiency, have poor power factor.

thumb_up_alt 0 like thumb_down_alt 0 dislike
73 views 1 answer
Description :

Field control of DC motor

Answer :

Field control of DC motor

thumb_up_alt 0 like thumb_down_alt 0 dislike
97 views 2 answers
Description :

Answer :

In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developed by the motor will remain unchanged.

thumb_up_alt 0 like thumb_down_alt 0 dislike
159 views 1 answer
Description :

Answer :

D.C. Series motor is generally preferred for cranes and hoists.

thumb_up_alt 0 like thumb_down_alt 0 dislike
88 views 1 answer
Description :

Answer :

Cumulatively compounded D.C. motor will be suitable along with flywheel for intermittent light and heavy loads.

thumb_up_alt 0 like thumb_down_alt 0 dislike
117 views 1 answer
Description :

Answer :

The type of D.C. motor used for shears and punches is cumulative compound D.C. motor.

thumb_up_alt 0 like thumb_down_alt 0 dislike
114 views 1 answer
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?

Answer :

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 series motor.

thumb_up_alt 0 like thumb_down_alt 0 dislike
213 views 1 answer
Description :

The speed of a D.C. motor can be controlled by varying  1. Its flux per pole 2. Resistance of armature circuit 3. Applied voltage 4. All of the above

Answer :

The speed of a D.C. motor can be controlled by varying  1. Its flux per pole 2. Resistance of armature circuit 3. Applied voltage 4. All of the above

thumb_up_alt 0 like thumb_down_alt 0 dislike
145 views 1 answer
Description :

Answer :

Sparking, is discouraged in a D.C. motor because commutator gets damaged.

thumb_up_alt 0 like thumb_down_alt 0 dislike
118 views 1 answer
Description :

Answer :

The speed of a D.C. series motor is inversely proportional to the armature current.

thumb_up_alt 0 like thumb_down_alt 0 dislike
76 views 1 answer
Description :

Answer :

The starting resistance of a D.C. motor is generally low.

thumb_up_alt 0 like thumb_down_alt 0 dislike
89 views 1 answer
Description :

Answer :

In case the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be less than 50%.

thumb_up_alt 0 like thumb_down_alt 0 dislike
119 views 1 answer
Description :

Answer :

For starting a D.C. motor a starter is required because it limits the starting current to a safe value.

thumb_up_alt 0 like thumb_down_alt 0 dislike
66 views 1 answer
Description :

Answer :

A D.C. series motor is that which has its field winding consisting of thick wire and less turns.

thumb_up_alt 0 like thumb_down_alt 0 dislike
58 views 1 answer
Description :

Answer :

The direction of rotation of a D.C. series motor can be changed by interchanging field terminals.

thumb_up_alt 0 like thumb_down_alt 0 dislike
79 views 1 answer
Description :

Answer :

A.C. series motor as compared to D.C. series motor has smaller brush width, less number of field turns, more number of armature turns, less air gap.

thumb_up_alt 0 like thumb_down_alt 0 dislike
76 views 1 answer
Description :

Answer :

The armature voltage control of D.C. motor provides constant torque drive.

thumb_up_alt 0 like thumb_down_alt 0 dislike
55 views 1 answer
Description :

Answer :

Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be cumulatively compounded.

thumb_up_alt 0 like thumb_down_alt 0 dislike
304 views 1 answer
thumb_up_alt 0 like thumb_down_alt 0 dislike
84 views 0 answers
Description :

Answer :

Differentially compounded D.C. motor has got maximum self loading property.

thumb_up_alt 0 like thumb_down_alt 0 dislike
64 views 1 answer
Description :

Answer :

The current drawn by the armature of D.C. motor is directly proportional to the torque required.

thumb_up_alt 0 like thumb_down_alt 0 dislike
360 views 1 answer
Description :

Answer :

Cumulative compound D.C. motor is preferred for elevators.

thumb_up_alt 0 like thumb_down_alt 0 dislike
88 views 1 answer
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?

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.

thumb_up_alt 0 like thumb_down_alt 0 dislike
85 views 1 answer
Description :

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

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.

thumb_up_alt 0 like thumb_down_alt 0 dislike
134 views 1 answer
editAsk a Question
...