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Which of the following will develop the maximum power by a DC motor?

Author

Avery Gonzales

Updated on March 06, 2026

Which of the following will develop the maximum power by a DC motor?

The condition for maximum power in case of D.C. motor is
Supply voltage =I × back e.m.f. D. Supply voltage = back e.m.f.

Keeping this in view, at what condition a DC motor will develop maximum power?

Condition for Maximum PowerThus maximum efficiency of a dc motor occurs when back EMF is equal to half the applied voltage.

Similarly, what is the condition for maximum efficiency in DC generator? Equation (1) shows that the efficiency of a DC generator is maximum when those losses proportional to the square of the load current are equal to the constant losses of the DC generator. This relation applies equally well to all rotating machines, regardless of the type of machine.

Additionally, what is the mechanical power developed by a dc series motor is maximum?

Back emf is equal to half the applied voltage. Back emf is equal to applied voltage. Back emf is equal to zero.

How do you control the speed of a DC motor?

Thus, the speed of a DC motor can be controlled in three ways:

  1. By varying the supply voltage.
  2. By varying the flux, and by varying the current through field winding.
  3. By varying the armature voltage, and by varying the armature resistance.

What is the efficiency of dc motor?

The value of the efficiency of a DC motor could typically be in the range of 70 to 85%. Larger the machine higher will be the efficiency. Losses consist of Armature and field copper losses, core loss, friction and windage loss.

What will happen if the back EMF of a DC motor vanishes suddenly?

Explanation: If back emf vanishes suddenly, motor circuit will try to retain back emf by drawing more current from supply. So, with the increase in speed, the back emf also increases. Therefore, armature current is also decreased, in case of series motor, armature current is equal to the line or load current.

Which power is mentioned on a nameplate of a motor?

Nameplate- defined parameters for the motor such as power factor, efficiency, torque, and current are at rated voltage and frequency. Application at other than nameplate voltage will likely produce different performance. It is common for manufacturers to nameplate a wide variety of voltages on one motor nameplate.

Which DC motor will be preferred for machine tools?

Which D.C. motor will be preferred for machine tools?
  • A. Series motor.
  • Shunt motor.
  • Cumulative compound motor.
  • Differential compound motor.

How do you calculate back EMF of a dc motor?

The back emf is calculated based on the difference between the supplied voltage and the loss from the current through the resistance. The power from each device is calculated from one of the power formulas based on the given information. The back emf is ϵi=ϵS−I(Rf+REa)=120V−(10A)(2.0Ω)=100.

For which of the following applications a DC motor is preferred over an AC motor?

The DC motors are preferred where higher starting torque is required for driving high inertia loads. The DC motor can deliver 250 % of the motor rated torque at start. Contrary to this, the induction motor takes the very high current at start, 6 times of the rated full load current and deliver low torque.

Which motor Cannot be started on no load?

In any DC motor the speed depends inversely on the flux and directly proportional to emf, N ~E/flux. At no load the armature current is very less and so is the flux, since the series winding has less number of turns.

What is armature reaction?

Armature reaction is the reaction or intereaction between the magnetic field produced by the flowing of current in the rectangular coil wound on the armature and the main magnetic field of the D.C. genarator or the motor. Installation of interpoles in the generator or motor to nullify the effect of armature reaction.

Which motor is constant speed?

DC shunt motor

How do you calculate the torque of a DC motor?

The torque equation of DC motor designs is torque = IBA_sin_θ for each turn of the motor with the electric current I in amps, magnetic field B in teslas, area outlined by the coil A in m2 and angle perpendicular to the coil wire "theta" θ.

What is the principle of torque generation in a DC machine?

Explanation: The electromagnetic torque generated in the dc generator is in the direction in which the prime mover is rotated.It is produced due to the action of armature current and stator field. Explanation: It is due to the fact that no field poles are induced in PMDC to create magnetic flux leading to harmonics.

Why does Series motor start with load?

In series motor field winding is in series to armature winding. In any DC motorthe speed depends inversely on the flux and directly proportional to emf, N ~E/flux. Motor armature current is decided by the load. On no load the armature current drawn by the motor will very small.

When the current in the shunt field is reduced the DC motor?

Intuitively we think that decreasing the field current should decrease the torque and motor should run slower. But exactly opposite happens. Because torque is dependent on both field current and armature current. When we reduce field current, Flux decreases and therefore according to (2), back emf (Eb) decreases.

What is the mechanical power developed by the motor?

For motor, Eb = Vt − IaRaMechanical power developed by the motor is given by Pm = EbIa ⇒ VtIa − Ia2Ra. Mechanical power developed by the motor will be maximum if dPm/dIa is zero.

When the DC motor is at rest the value of the back EMF is?

The back emf is proportional to the speed N. It is zero at standstill . Back emf opposes the supply voltage and limits the armature current to a safe value.

What happens if the field circuit of a DC shunt motor is opened?

In d.c shunt motor if field winding supply is removed the motor back emf will drop to zero, hence the armature will draw more current to make up the emf. this results in blowing up of fuse. In dc series motor the motor will go to infinite speed (theoretically) as flux is inversely proportional to the speed

Which of the following windings are necessary in case of all DC machines?

In case of all DC machines we must use closed winding. Lap and wave windings are used based on the requirement of voltage and current levels, but winding of all DC machines is closed winding.

Can a DC motor run on AC?

Yes. A DC series motor is capable of running when supplied with a single phase AC supply. This is because the torque, which varies as the product of the armature and field current, is always positive. Thus, a positive average torque causes the motor to rotate.

What is the most efficient generator?

The Yamaha EF2000iS 2,000W gas powered inverter generator is the most silent, portable and fuel efficient generator on the market today. And for the price, it offers extreme value for the money.

What is generator efficiency?

Generator efficiency is the “ratio of output power (electrical power) obtained from the generator to the input power (mechanical power) supplied to the generator”. As the generator converts the mechanical energy into electrical energy, the output power available at the generator's output is electrical in nature.

Why generator efficiency is more than motor?

In general, the efficiency of a generator will be greater than that of motor. Some of the reasons are, The generator windings are made of more thicker windings hence have lesser resistance and hence lower copper losses . but in generator there are no opposing voltages .

What are the losses in DC generator?

In a DC machine, there are only two windings, armature and field winding. Thus copper losses categories in three parts; armature loss, the field winding loss, and brush contact resistance loss. The copper losses are proportional to the square of the current flowing through the winding.

What is the condition for maximum efficiency of a transformer?

Condition for maximum efficiency
Hence, efficiency of a transformer will be maximum when copper loss and iron losses are equal. That is Copper loss = Iron loss.

How do dc machines reduce losses?

As there are no eddy current losses the field poles need not be laminated. To minimize losses at the magnetic poles, one can make them permanent magnets or if they are wound, one must choose good copper wire with best conduction paths and good insulation.

What is the condition for maximum torque of a DC shunt motor?

The basic condition of transferring maximum power by DC shunt motor is to make the core loss equals to the copper loss of the shunt motor… Core loss is the constant loss it does not depend on load it is the minimum loss that is taken place in shunt motor if we reduce the copper loss then our efficiency increases..

How do you calculate the efficiency of a generator?

The efficiency of a generator is determined by the power of the load circuit and the total watts produced by the generator. It is expressed as a percentage since you are dividing units of power by units of power. For most commercial electrical generators, this ratio can be upwards of 95 percent.

How do you increase the speed of a 12v DC motor?

By adding more poles / magnets thus increasing magnetic flux… By also reducing a liitle bit the number of turns in your field windings…which will force the production of much stronger magnetic flux, using the limited current supply…

What are the factors that affect the speed of a DC motor?

Factors Affecting The Speed Of Dc Motor
  • The applied voltage.
  • The flux.
  • The voltage across an armature.

What is position control of DC motor?

The position control of a DC motor is crucial in applications for precision control system. The purpose of a motor position controller is to take a signal representing the required angle and to drive a motor at that position. Microcontrollers can provide easy control of a DC motor.

What are the applications of DC motor?

Applications. DC motors are suitable for many applications – including conveyors, turntables and others for which adjustable speed and constant or low-speed torque are required. They also work well in dynamic braking and reversing applications, which are common in many industrial machines.

How can we increase the rpm of dc motor?

So, as the magnetic field increases, the speed will decrease. This again makes sense because the stronger the magnetic field, the stronger the "push" on the armature so it will resist a change in speed. So any change to torque or speed will be directly proportional to the power required to drive the motor.

How is an SCR used to control the speed of a DC motor?

The speed of DC motor can be control by usingSCRin AC circuit as shown in the below figure. The SCR A and B rectifier, the o/p voltage of transformer T1 and apply this pulsating DC voltages to the armature winding and rectifier “C” supplies similar voltages to the motor field winding.

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Which of the following will develop the maximum power by a DC motor?