# What will happen if a shunt DC motor is directly connected to the supply line?

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## What will happen when the DC shunt motor is connected to AC supply?

The Shunt winding has a large number of turns so that it has appreciable inductance. When A.C is applied to a shunt motor, the large inductive reactance of shunt winding will reduce the field current too much. Consequently, Shunt motor will not usually run on A.C Supply.

## What will happen if the field of a DC shunt motor is opened while the motor is running?

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. The magnitude of this current may be sufficient to burn out the motor.

## When motor is directly connected to main supply armature draws?

As the DOL starter connects the motor directly to the main supply line, the motor draws a very high current compared to the full load current of the motor (up to 5-8 times higher). The value of this large current decreases as the motor reaches its rated speed.

## What will happen when DC motor is connected to AC supply then Mcq?

burn. run at lower speed. If a DC series motor is connected to an AC supply same current will flow through the series field and armature field after being rectified by the commutator. So, the machine will run but with high sparking at brush, poor pf, low speed and low efficiency.

## What will happen if a shunt motor running at no load has its shunt field winding opened accidentally?

Ans: if a shunt motor, running at no load has its shunt field opened or burnt out, the back emf will fall to nearly zero . the armature current will continuously increase the speed of the motor until its parts fly apart.

## Why DC shunt motor should be started without load?

Since speed is constant and torque (τ) is proportional to armature current (Ia). So that, starting a shunt motor at a heavy load requires a high starting current. In order to avoid this high starting current, shunt motors are not started at heavy loads and they should be started without any load.

## What will happen if DC motor is used without starter?

What will happen if DC motor is used without starter? Explanation: It would cause intolerably heavy sparking at the brushes which may destroy the commutator and brush-gear. … Explanation: In shunt and compound motors starting the shunt field should be switched on with full starting resistance in armature circuit.

## What are the advantages and disadvantages of a DC shunt motor?

The installation of DC machines is expensive compare with other types of machines. Shunt motor is a constant speed motor, it would be disadvantages where it’s necessary to operate under variable speed. For the same current input, its starting torque is not a high as that of a DC series motor.

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## What will happen if the field circuit breaks down?

In the case of a series machine if field winding disconnected, then the motor circuit is open and no current will pass through the armature, for the operation of machine interaction of two fluxes is necessary thus the machine won’t operate.