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.
Which motor should not be started at no load?
If it is started without load the field current will be less, hence flux will be less and due to this motor speed will go infinite and damages itself. This is the reason why series motor should not be started without load and shunt motor can be started without load. , Made my first DC motor at age of 7.
Which of the following machine should not be started at no load Mcq?
6. Which motor should not be started on no-load? Explanation: No-load speed of the DC motor is very high, it’ll create a dangerous situation and the centrifugal forces will destroy the armature and may harm the personnel.
Which can be started on no load Unlike DC series motor?
Unlike DC series motor, DC compound motor can be started on no-load. Explanation: Cumulative motor takes best from shunt motor and series motor as well. Due to shunt field flux component, DC cumulative motor can be started on no load.
When motor runs on no load then?
When the motor is connected across the supply mains without load, it draws small current from the supply mains. This current will flow through the series field and armature, the speed tends to increase so that back emf may approach the applied voltage in magnitude.
Why a DC series motor should not be started without load Mcq?
at no load, it will rotate at dangerously high speed. at no load, it will rotate at dangerously high speed. …
Why DC shunt motor is started on no load?
For DC shunt motor the field resistance is high and armature resistance is low so the variation of flux is very less when rated voltage is applied to the motor and motor speed does not exceeds rated speed at no load. So we can start the DC shunt motor with no load.
Which of the following is not a type of stepper motor?
Which among the following is not the type of a stepper motor? Explanation: Variable magnet is not the type of a stepper motor. Variable reluctance stepper motor consists of a soft iron multi-toothed rotor and a wound stator. Permanent magnet stepper motors have a rotor made up of the permanent magnet.
What all may happen if the DC shunt motor running on no load has its shunt field winding opened accidentally?
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.
Why Swinburne test is called No load Test?
The Swinburne test is an indirect method for determining the efficiency of DC motors. It works by finding the no-load losses experimentally and then estimating additional losses from the rated motor data. … Because the motor is running at no-load condition, the net output is zero.
Which motor is used in hair dryer?
Conventional hair dryers traditionally make use of AC universal motors capable of achieving high-speed rotation while operating on single-phase power supplies commonly used in households.