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 would 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…
What will happen if field winding terminal will be open circuited?
“The fact that full field or armature voltage might exist across an open circuited field winding means very little as no current can / will flow through it.” … Hence, now E is forced to the system, and as long as the voltage terminal is on, E is going to be Vt-RaIa.
What will happen if the shunt field winding opened accidentally during the experiment?
Ans: if the shunt field winding of a loaded shunt motor accidentally breaks, the loss of shunt field current would result in stopping of the motor or burn out the armature or fuse.
What will happen to the DC compound motor if the shunt field is opened when the motor is operating at light load?
Explanation: If shunt field is suddenly opened, flux due to shunt field will become 0. As, net flux is equal to shunt field flux – series field flux, the direction of flux will be reversed and thus motor will run in opposite directions.
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.
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.
Why is it dangerous to lose the field of a shunt motor?
Now cutting off the field winding is dangerous for shunt dc motor. As for shunt motor, speed is inversely proportional to field current, so cutting off the field winding results in dangerously high speed. Thus motor gets damaged.
What happened to the DC motor if it run without any starter explain in details?
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. Sudden development of large torque will cause mechanical shock to the shaft, reducing its life.
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.
Why is the speed of DC shunt motor dependent on back EMF?
In the case of DC motors Speed ∝ Back emf(Eb)/flux(φ). The field winding is connected across the armature. … As current is constant flux also becomes constant b the cause flux is directly proportional to current. Therefore the speed of the DC shunt motor depends on the back EMF.
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 happens when DC motor is connected to AC supply?
When DC motor is excited by an AC source ,the DC motor will run but the motor will vibrate . When AC motor is supplied with DC the motor won’t run since the induction isn’t possible . A DC motor connected a ac supply then motor pulsating and less efficient working.
Which DC motor has maximum self loading property?
1 Answer. Series motor has got maximum self relieving property.