If u start the motor without load the speed will increase. as speed increases the back emf increases. … 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.
Which motor is always started with load?
At no load, it will rotate at dangerously high speed 2. It will fail to start 3. It will not develop high starting torque 4.
Why does Series motor tend to race at no load and light loads?
According to speed equation, N α 1/Φ as Eb is almost constant. So on very light load or no load as flux is very small, the motor tries to run at dangerously high speed which may damage the motor mechanically. … This is the reason why series motor should never be started on light loads or no load conditions.
Why series motors are not operated at no load?
A series motor should never be started at no load. With no mechanical load on the series motor, the current is low, the counter-EMF produced by the field winding is weak, and so the armature must turn faster to produce sufficient counter-EMF to balance the supply voltage. The motor can be damaged by overspeed.
Why do DC series motors start heavy loads?
The DC series motor provides high starting torque because the field and armature winding are connected in the series and carry the same current. … That is why DC series motor is capable to produce high starting torque, and it is preferred for driving heavy loads.
Can we start the DC shunt motor and series motor without load?
We can operate a shunt motor with no load because their torque is not that high as series motors. They are moreover constant speed motors and tend to operate at stable speeds. Series motors cannot be started without load, as they tend to overspeed and get damaged. Motor armature current is decided by the load.
When load is removed motor will run at the highest speed?
1 Answer. When load is removed, series motor will run at the highest speed.
Is advised not to run dc series motor with no load why?
It is advised not to run dc series motor with no load. … Explanation: If the torque is zero in dc series motor then the speed will be infinite causing the damage of the machine permanently.
What will happen when DC shunt motor is started with load?
Answer : Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease. Answer : With the increase in load on a d.c. shunt motor, speed of the motor reduces slightly.
Which motor should be started on no load?
The d.C. Series motor should always be started with load because 1. At no load, it will rotate at dangerously high speed 2. It will fail to start 3.
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.
Which DC motor has got maximum self relieving property?
Series motor has got maximum self relieving property.
Which type of load is connected to the DC series motor?
A series DC motor connects the armature and field windings in series with a common D.C. power source. The motor speed varies as a non-linear function of load torque and armature current; current is common to both the stator and rotor yielding current squared (I^2) behavior.
Which type of DC motor can start with heavy loads?
The starting torque of the DC series motor is proportional to the square of the armature current. The armature current-Torque characteristics of the DC series motor is as given below. That is why DC series motor is capable to produce high starting torque, and it is preferred for driving heavy loads.
Which DC motor is preferred for heavy loads?
4. Which DC motor is used with flywheel for intermittent light and heavy loads? Explanation: Cumulative compound DC motor is used with flywheel carrying peaks and so to smooth out the load on the motor as well as to reduce peaks on power system. Without flywheel the motor construction will be much larger.
Which type of DC motor is used for sudden application of heavy loads?
Like dc series motor, a dc cumulatively compounded dc motor has also variable speed, adjustable variable speed, and high starting torque. We use cumulatively compounded dc motors for intermittent high torque loads, shears, punches, elevators, conveyors, heavy planers and rolling mills, etc.