0
If a DC series motor is started without load, the armature winding (winding that doesn't spin) current will be at a minimum, resulting in the motor going to maximum speed / runaway, which can cause things to fly apart. As Armature current increases, the speed of the motor will decrease. The armature current will be forced to increase / speed of the motor will be forced to decrease as more and more load is applied.
Wiki User
∙ 14y ago
Wiki User
∙ 12y agodc series motor should not be operated on no-load because the speed in the starting will be infinty, on starting the dc sereis motor we always but a starting resistance.
Add your answer:
Earn +20 pts
Why a DC series motor should never be stared without load?
since torque is proportional to flux and armature current . Flux for dc shunt is constant . torque is proportional to armature current only. And initially armature current is very low hence it cannot be started at load .
How do you start a DC motor if there is no 3 point starter?
By the use of auto transformer and bridge rectifier we can start dc motor.
Why the series motor is started with some minimum load?
In series motor, At no Load Condition the flow of Armature Current is low, then the Flux is also low. Flux is inversely proportional to speed. If flux is decrease the speed is rapidly increase it spoil the rotor parts...... so SERIES MOTOR is start with LOAD.....
How do you wire start and run capacitors into an electric motor?
Connect your start capacitor in series with the start winding.Connect the run capacitor in the common terminal and Line 1 of the power supply.
Why is Dc series motor used to start at heavy load?
due to its high initial torque value. the DC series motor is a Constant power motor, equal to the RATED POWER if it has at rated value of the U and I. Angular velocity=Rated Power/Torque, so Torque =Rated Power/Angular Velocity thus, in the start the velocity is zero or near, so, the Torque is infinit or very higt
Which motor does not start on dc?
All AC motors except for a Series Motor.
Why a DC series motor should never be stared without load?
since torque is proportional to flux and armature current . Flux for dc shunt is constant . torque is proportional to armature current only. And initially armature current is very low hence it cannot be started at load .
Why should a series motor always start with a load?
In any DC motor the speed depends inversely on the flux. Consider when starting a series motor the current flowing will be high, but the flux that the motor produces will be moderate since the series winding has less number of turns. If u start the motor without load the speed will increase. as speed increases the back emf increases. this decreases the current through the series winding and hence flux decreases and the speed further increases. Theoretically speaking the speed becomes infinite. But practically the motor will accelerate to very high speed , which will damage the motor. But if you start the motor with the load, you are actually reducing the starting speed hence the motor runs safely. Since series motors has this property it is used in trains to pull high load.
How do you start a motor without a starter?
By the use of auto transformer and bridge rectifier we can start dc motor.
How do you reverse the rotation of a 110 volt motor?
As long as it is an induction 110 volt motor it can be reversed; if it is any other type of motor it cannot be reversed. You will have to get into the windings to bring both leads to the start in order to make it go in reverse. <<>> A split phase induction motor has two sets of coils and a centrifugal start switch. The start winding is in series with the start switch. The start winding provides a rotating magnetic field in one direction enabling the motor to start. The motor can be reversed by reversing the connections of either the start winding or the run winding but not both.
Can i not use a capacitor on a motor equipted with the motor?
No. You won't be able to start the motor without the capacitor.
Why the series motor is started with some initial load?
In dc motors Speed is directly proportional to back emf and inversely proportional to flux i.e N∝(Eb/φ) In series motor back emf is practically constant. So if we start motor without any load Flux will be small and so speed will be very high. if we start motor without any load it will gain very high speed and may get damaged due to centrifugal forces. Series motor have very high starting torque and used where high starting torque is required.
Can a shunt motor be started without residual magnetism?
Yes. The field is provided by the shunt windings, which are connected in parallel with the supply. You may be confusing a motor with a generator, as you cannot start a shunt generatorwithout residual magnetism.
How do you know if motor is locked up?
A motor that is locked up cannot make a rotation. The motor will not turn over or start. Try to turn the main pulley. When the pulley cannot be by just, the motor is locked up.
What happend when you start motor without starter?
The windings of the motor will be gonebecause of high current diectly goes to the windings of motor.
How supply takes the dc series motor in the train?
fast start low speed
Why can we start a shunt motor under no load but why can't a series motor?
The torque on a series motor is determined by the square of the armature current and, so, is very large -much larger than that of a shunt motor. Consequently, on starting, with no back-emf being generated, the torque on a series motor can be dangerously high if the machine has no mechanical load.
