What is the effect in a DC shunt motor?

When both (the direction of the field as well as that of armature current) are reversed the direction of rotation will not change. So in the case of DC shunt motor, if the supply terminals are interchanged, there is no change in the direction of rotation.

What are the factors that influence the torque of DC motor?

The torque is dependant on how large a magnet field the engine generates, and this is mostly dependant on the current it draws and the number of turns in the coil. So the thickness of the wire has no effect except if it affects the resistance and therefore the current drawn.

What is efficiency of a DC motor and state the condition of maximum efficiency?

Hence, to determine the condition for maximum efficiency, differentiating the denominator of the eqn. (3) with respect to armature current and equating it to zero, i.e. Therefore, the maximum efficiency occurs in a DC motor when the variable losses become equal to the constant losses for the motor.

What is the efficiency range of DC shunt motor?

Order of efficiency of rotating d.c machine is about 80 \% to 85 \%.

What is the starting torque of DC shunt motor?

The starting torque for this motor is about 1.5 times the full-load torque (Figure 7-49). This is sufficient to start this type of motor while under full load. The shunt motor, however, has the lowest starting torque of any of the other DC motors.

Which has stronger torque series motor or shunt motor?

The field flux, then is proportional to armature current. For light loads a series motor produces less toryue for the same arrnature current; for heavy loads it produces more torque than a shunt motor. Series motors are alwaye rigtdly connected to their loads, and never operated without some Ioad.

What are the factors affecting torque?

Examples: Page 5 Torque is Determined by Three Factors: The magnitude of the applied force. The direction of the applied force. The location of the applied force.

How is torque developed in a DC motor?

When a DC machine is loaded either as a motor or as a generator, the rotor conductors carry current. These conductors lie in the magnetic field of the air gap. Thus, each conductor experiences a force. Hence, a torque is produced around the circumference of the rotor, and the rotor starts rotating.

How would you define the efficiency of a DC generator?

The efficiency of a DC generator is defined as the ratio of mechanical input power to the output electrical power.

What is efficiency in DC machine?

Efficiency is simply defined as the ratio of output power to the input power. Let R be the total resistance of the armature circuit (including the brush contact resistance, at series winding resistance, inter-pole winding resistance and compensating winding resistance).

How is DC shunt motor efficiency calculated?

The overall efficiency of a DC motor can be found in a similar manner to that of a DC generator, that is: power input = power output + losses. Whereas the input to a generator was mechanical power and the output electrical power, the input to a motor is electrical power and the output mechanical power.

What is the typical efficiency of a DC motor?

The motors are normally designed to have maximum efficiency while working at or near full load. The efficiency of a dc motor at normal operating conditions may be as high as 95\%. A typical efficiency curve showing the manner in which the efficiency varies with the output is shown in Fig.

What are the characteristics of a DC shunt motor?

In Fig. 1.17, four important characteristics of a dc shunt motor, namely, torque, speed, armature current, and efficiency, each plotted against the useful output power, are shown. These curves are also known as performance curves of a motor.

When does the efficiency of a shunt machine become maximum?

The efficiency of the shunt machine becomes maximum when variable loss is equal to the constant loss. From armature current-output power curve, a certain value of current is required even when the output is zero. The motor input power under no-load condi­tions is consumed in meeting the various losses occurring within the machine.

What is the overall efficiency of a DC motor?

The overall efficiency of the dc motor is the ratio of output power to the input power. We also call it as commercial efficiency. This is the ratio of armature power to the input electrical power. This efficiency determines, how efficiently a motor delivers the armature power to the shaft for doing desired mechanical work by the machine.

Can a shunt motor start a heavy load?

A shunt wound motor is said to have a low starting torque as compared to other motors but it does not mean that a shunt motor is incapable of starting a heavy load. A shunt motor is capable of starting heavy load also but it would require more excess of current input over normal values than the series and compound motors.