Question: What would happen if the field of DC shunt motor is open?

If the shunt field suddenly opens while the motor is being operated under full-load conditions, only a small voltage due to the residual magnetism of the pole pieces will be induced into the armature. Current will increase considerably. … Under these conditions, the motor will act as a series DC motor.

What will happen if the field of DC shunt motor is opened?

Answer: n 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…

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What will happen when the field of DC shunt motor gets opened while the motor is running Mcq?

What will be the effect of opening of field of a DC shunt motor while motor is running? Explanation: In a DC shunt motor if supply for the field winding is cut down, the speed would dangerously increase in order to maintain the back emf of the motor.

What will happen if the DC shunt motor field winding opened accidentally running on no load?

What will happen if the d.c. shunt motor opened accidentally running on no-load has its shunt field winding? The field will be reduced to only to the value of residual flux. The speed will be very high. The parts of motor may even fly apart.

What will happen if excitation of DC shunt motor is changed?

2. What will happen if excitation of DC shunt motor is changed? … Explanation: Speed of the DC motor obtained from speed equation is inversely proportional to flux produced by the field. So, reducing the field current flux produced by armature will decrease, and speed will increase.

Why starter is used in DC shunt motor?

Starters are used to protect DC motors from damage that can be caused by very high current and torque during startup. They do this by providing external resistance to the motor, which is connected in series to the motor’s armature winding and restricts the current to an acceptable level.

What are the advantages of DC shunt motor?

Advantages of Dc shunt motor:

  • The power supply of the DC motor is any way cheap.
  • Shunt would motor able to runs at a predetermined speed.
  • The speed of a dc shunt motor is sufficiently constant.
  • Direct current machines can use for heavy industrial applications where the torque and speed wider range.
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What is a DC shunt motor?

A shunt motor (known as a shunt wound DC motor) is a type of DC motor which is self-excited and has the field windings that are connected in parallel to the armature winding of the motor. As these two parts are connected in parallel, the armature and field windings are exposed to the same supply voltage.

How speed of DC shunt motor is controlled?

Field Rheostat Controlled DC Shunt Motor

In this method, speed variation is accomplished by means of a variable resistance inserted in series with the shunt field. An increase in controlling resistances reduces the field current with a reduction in flux and an increase in speed.

Which DC motor has maximum self loading property?

Which DC motor has got maximum self-loading property? Explanation: A differentially compound DC motor, flux reduces so sharply at small increase in load at higher values of load. It is advisable that motor should not be used beyond some load value, as it may damage itself by self-loading.

Which motor has the poorest speed control?

Which of the following DC motor has the poorest speed control? Explanation: DC series motor at no load condition gives infinite speed ideally. Practically it will damage all the armature circuit.

What are the applications of DC shunt motor?

DC Shunt Motor Applications

  • These motors are used wherever stable speed is required.
  • This kind of DC motor can be used in Centrifugal Pumps, Lifts, Weaving Machine, Lathe Machines, Blowers, Fans, Conveyors, Spinning machines, etc.

What happens if excitation is changed?

A change in the excitation, thus, affects only the power factor of its output. … This reduces the terminal voltage slightly, so let the excitation of the first alternator be increased so as to bring the terminal voltage back to its original value.

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What is the speed of dc motor?

DC controls adjust speed by varying the voltage sent to the motor (this differs from AC motor controls which adjust the line frequency to the motor). Typical no load or synchronous speeds for an AC fractional horsepower motor are 1800 or 3600 rpm, and 1000-5000 rpm for DC fractional hp motors.

What will happen to the speed of the DC shunt motor when the flux is increased?

The speed will increase abruptly. The speed will remains almost constant. The speed will increase in proportion to reduction in load. In case of DC shunt motor, flux is practically constant as field is parallel to the armature.

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