# Which D.C. motor has got maximum self relieving property ?

Series motor has got maximum self relieving property.

## Related questions

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.

Description : A synchronous motor can be made self starting by providing?

Answer : A synchronous motor can be made self-starting by providing damper bar.

Description : How is a three phase cage induction motor self starting?

Answer : Any type of induction motor is self starting. Because the reason for torqe production require two flux displaced by some angle theta.If theta is constant with time then torqe will be constant;if ... torqe also pulsating. In induction motor this angle theta is not pulsating.so it is self starting

Description : Is induction motor is self starting?

Answer : Single phase induction motor is not self starting. Three phase induction motor is self starting.

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.

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.

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?

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

Answer : The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is 0.5.

Answer : In repulsion motor, maximum torque is developed when brush axis is at 45° electrical to the field axis.

Description : What is the maximum value of torque angle in synchronous motor?

Answer : The maximum value of torque angle in synchronous motor is 90 degrees electrical.

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.

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.

Answer : Shunt motors,  Series motors, Compound motors

Answer : D.C. generators are normally designed for maximum efficiency around full-load.

Answer : The condition for maximum efficiency for a D.C. generator is variable losses equal to constant losses.

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

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

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

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

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?

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?

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

Answer : Commutator provides unidirectional torque and pulsating dc

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.

Answer : When the armature of a D.C. motor rotates, e.m.f. induced is back e.m.f.

Answer : Torque developed by a D.C. motor depends upon magnetic field, active length of the conductor, current flow through the conductors, number of conductors, radius of armature.

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

Description : State maximum power transfer theorem for DC circuit.

Answer : Maximum power transfer theorem for DC circuit: The maximum power transfer theorem states that the source or a network transfers maximum power to load only when the load resistance is equal ... removed (disconnected) ii) All internal independent sources are replaced by their internal resistances.

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

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 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.

Description : In DC motor iron losses are occurred in?

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

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%.

Description : The property of a material which opposes the creation of magnetic flux in it is known as?

Answer : The property of a material which opposes the creation of magnetic flux in it is known as reluctance.

Description : The maximum torque of d.c. motors is limited by?

Answer : The maximum torque of d.c. motors is limited by commutation.

Description : A suspension type insulator has 2 units with self capacitance C and ground capacitance of 0.2 C. Each unit can withstand for a maximum voltage of 11 kV. Its string efficiency is  (A) 78% (B) 82% (C) 80% (D) 84%

Description : Explain magnetostriction property. Explain generation of ultrasonic using magnetostriction

Answer : When a ferromagnetic material is magnetized then the material exhibit small change in its dimensions, this phenomenon is called magnetostriction effect. Iron crystal expands when magnetized in ... waves  1.ultrasonic signaling 2.ultrasonic cleaning 3.ultrasonic soldering 4.ultrasonic drilling.

Description : Problem on eigen values property

Answer : Problem on eigen values property https://youtu.be/DoSTY-bBubQ

Description : Linearity property

Answer : Linearity property 1 : https://youtu.be/-iaXB3uvX9k Linearity property 2 : https://youtu.be/CbO8Mnw5v_o Linearity property 3 : https://youtu.be/P6GiYv5MCFI Linearity property 4 : https://youtu.be/ ... property 5 : https://youtu.be/KxkSkUkz8FY Linearity property 6 : https://youtu.be/W-F_vBifgZI

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.

Description : Why a dc series motor has a high starting torque?

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

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

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

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

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

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.

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

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

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

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