Answer :
In case of D.C. shunt motors the speed is dependent on back e.m.f. only because flux is practically constant in D:C. shunt motors.
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
Answer :
The armature may burn if the back e.m.f. of a D.C. motor vanishes suddenly.
asked
Mar 20, 2018
by
anonymous
Description : The mechanical power developed by the armature of a d.c. motor is equal to?
Answer :
The mechanical power developed by the armature of a d.c. motor is equal to armature current multiplied by back e.m.f.
asked
Mar 26, 2018
by
anonymous
Answer :
If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will increase.
asked
Mar 20, 2018
by
anonymous
Description : What is the back EMF of a dc motor?
asked
Mar 15, 2018
by
anonymous
Description : The back emf of synchronous motor depends on?
Answer :
The back emf of synchronous motor depends on load angle.
asked
Mar 18, 2018
by
anonymous
Description : What is back EMF of synchronous motor?
asked
Mar 15, 2018
by
anonymous
Description : What is the back EMF of the motor?
asked
Mar 15, 2018
by
anonymous
Description : The synchronous motor will develop maximum power when the load angle is?
Answer :
The synchronous motor will develop maximum power when the load angle is 900.
asked
Mar 18, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
Description : In a d.c. motor, the mechanical output power actually comes from?
Answer :
In a d.c. motor, the mechanical output power actually comes from electrical input power.
asked
Mar 26, 2018
by
anonymous
Description : The synchronous motor which works on leading power factor and does not drive any mechanical load is called?
Answer :
The synchronous motor which works on leading power factor and does not drive any mechanical load is called synchronous condenser.
asked
Mar 18, 2018
by
anonymous
Description : The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is (A) 0.25 pu (B) 0.5 pu (C) 1.0 pu (D) 1.5 pu
Answer :
The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is 0.5 pu
asked
Apr 28, 2018
by
anonymous
asked
Mar 20, 2018
by
anonymous
Answer :
In repulsion motor, maximum torque is developed when brush axis is at 45° electrical to the field axis.
asked
Mar 20, 2018
by
anonymous
Description : An independent voltage source in series with an impedance ZS=R+jXS delivers a maximum average power to a load impedance ZL when A) ZL = R B) ZL = jXS C) ZL = R-jXS D) ZL = R+jXS
Answer :
An independent voltage source in series with an impedance ZS=R+jXS delivers a maximum average power to a load impedance ZL when ZL = R-jXS
asked
Jun 18, 2018
by
anonymous
Answer :
When the armature of a D.C. motor rotates, e.m.f. induced is back e.m.f.
asked
Mar 20, 2018
by
anonymous
Description : The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as?
Answer :
The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as pull-in torque.
asked
Mar 20, 2018
by
anonymous
Description : The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as?
asked
Mar 20, 2018
by
anonymous
Description : The counter e.m.f. of a d.c. motor?
Answer :
The counter e.m.f. of a d.c. motor helps in energy conversion.
asked
Mar 26, 2018
by
anonymous
Answer :
The speed of a D.C. shunt motor can be increased by increasing the resistance in field circuit.
asked
Mar 20, 2018
by
anonymous
Answer :
The speed of a D.C. shunt motor more than its full-load speed can be obtained by decreasing the field current.
asked
Mar 20, 2018
by
anonymous
Answer :
A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave will be of 5 Hz.
asked
Mar 21, 2018
by
anonymous
Description : Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be
Answer :
Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be 25 N -m
asked
Apr 29, 2018
by
anonymous
Answer :
As the load is increased the speed of D.C. shunt motor will reduce slightly.
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
Description : What is back emf?
Answer :
Back EMF: When a current carrying conductor is placed in a magnetic field it experiences a force; when it moves due to the force it (conductor) cuts the magnetic field due to which an emf is ... (hence the applied armature voltage) is opposed by the induced emf which is therefore called as Back emf.
asked
Apr 27, 2020
by
anonymous
Description : Do AC induction motors have back EMF?
asked
Mar 15, 2018
by
anonymous
Description : What is back EMF in inductor?
asked
Mar 15, 2018
by
anonymous
Description : What is the back EMF in Transformers?
asked
Mar 15, 2018
by
anonymous
Description : What is the back EMF?
Answer :
When the armature of a d.c. motor rotates under the influence of the driving torque, the armature conductors move through the magnetic field and hence e.m.f. is induced in them as in a generator. The ... that energy conversion in a d.c. motor is only possible due to the production of back emf.
asked
Mar 15, 2018
by
anonymous
Answer :
The armature torque of the D.C. shunt motor is proportional to armature current.
asked
Mar 20, 2018
by
anonymous
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
asked
May 8, 2018
by
anonymous
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
asked
May 3, 2018
by
anonymous
Answer :
For a D.C. shunt motor if the excitation is changed torque will change but power will remain constant.
asked
Mar 20, 2018
by
anonymous
Answer :
In a D.C. shunt motor, speed is independent of armature current.
asked
Mar 20, 2018
by
anonymous
Answer :
If the field of a D.C. shunt motor gets opened while motor is running the motor will attain dangerously high speed.
asked
Mar 20, 2018
by
anonymous
Description : A shunt generator running at 1000 r.p.m. has generated e.m.f. as 200 V. If the speed increases to 1200 r.p.m., the generated e.m.f. will be nearly?
Answer :
A shunt generator running at 1000 r.p.m. has generated e.m.f. as 200 V. If the speed increases to 1200 r.p.m., the generated e.m.f. will be nearly 240 V.
asked
Mar 21, 2018
by
anonymous
Description : The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be?
Answer :
The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be 580 V.
asked
Mar 21, 2018
by
anonymous
Description : A change of 4% in the supply voltage to an induction motor will produce a change of approximately
Answer :
A change of 4% in the supply voltage to an induction motor will produce a change of approximately 8% in the rotor torque
asked
May 8, 2018
by
anonymous
Description : The voltage transformation ratio of a transformer is equal to the ratio of?
Answer :
The voltage transformation ratio of a transformer is equal to the ratio of secondary induced e.m.f. to primary induced e.m.f.
asked
Mar 19, 2018
by
anonymous
Description : "Maximum power output is obtained from a network when the load resistance is equal to the output resistance of the network as seen from the terminals of the load". The above statement is associated with?
Answer :
"Maximum power output is obtained from a network when the load resistance is equal to the output resistance of the network as seen from the terminals of the load". The above statement is associated with Maximum power transfer theorem.
asked
Mar 25, 2018
by
anonymous
Answer :
Power plant having maximum demand more than the installed rated capacity will have utilisation factor more than unity.
asked
Mar 20, 2018
by
anonymous
Answer :
When a D.C. series motor is connected to A.C. supply, the power factor will be low because of high inductance of field and armature circuits.
asked
Mar 20, 2018
by
anonymous
Description : A dc chopper is fed from a constant voltage mains the duty ratio of chopper is progressively increased while the chopper feeds an RL load. The per unit current ripple would (1) increase progressively (2) decrease progressively (3) decrease to a minimum value at α = 0.5 and then increase (4) increase to a maximum value at α = 0.5 and then decrease
Answer :
A dc chopper is fed from a constant voltage mains the duty ratio of chopper is progressively increased while the chopper feeds an RL load. The per unit current ripple would increase to a maximum value at α = 0.5 and then decrease
asked
Apr 30, 2018
by
anonymous
Description : Voltage ratio
Answer :
Voltage ratio
asked
Jun 11, 2019
by
anonymous
Description : Define: 1) voltage ratio, 2) current ratio, 3) transformation ratio of transformer.
Answer :
1) Voltage ratio: The voltages in primary and secondary winding is proportional to number of turns in primary and secondary respectively. So, the voltage ratio is same as transformation ratio. V2/V1 = N2 ... as transformation ratio of transformer. It is denoted by K. K = N2/N1
asked
Aug 12, 2018
by
anonymous
Description : For maximum transfer of power, internal resistance of the source should be?
Answer :
For maximum transfer of power, internal resistance of the source should be equal to load resistance.
asked
Mar 25, 2018
by
anonymous