The induction motor draws a high starting current as compared to the running condition. The starting current of the induction motor is about 5 or 6 times the motor full load current.
Why motor starting current is high?
At start, the reactance of the rotor is high because the slip of the motor is equal to unity. The value of Rr/s increase as the slip gets decrease. When the induction motor is started the rotor reactance is more than the rotor resistance and because of the large Xr/Rr ratio the motor takes large inductive current.
Which motor has high starting torque and starting current?
Series wound DC motors are best for applications that require high startup torque, without the need for speed regulation. Like a shunt motor, as a load is applied to a DC series motor, the motor speed decreases, which reduces the back EMF and increases the net voltage.
Which one of the following motor has high starting torque?
The capacitor start motor develops a much higher starting torque of about 3 to 4.5 times of the full load torque.
In which method of starting a motor the starting current is the maximum?
Explanation: At starting when slip is 1, the voltage induced is maximum. Explanation: Starters are needed in induction motors to limit the starting current.
Why is DC motor current so high?
Answer: The starting current is high as there is no back EMF or counter EMF present in the armature circuit because atstarting counter EMF is zero. … It’s armature has very less resistance due to this it need more current at starting time. Hence DC starters are used to limit the starting current ofmotor.
How long does motor starting current last?
After the first half-cycle the motor begins to rotate and the starting current subsides to 4 to 8 times the normal current for several seconds. As a motor reaches running speed, the current subsides to its normal running level. Typical motor starting characteristics are shown in Curve 1.
Which motor has a poor starting torque?
When a capacitor short-circuits, the winding in the motor may burn out. When a capacitor deteriorates or opens, the motor has poor starting torque. Poor starting torque may prevent the motor from starting, which will usually trip the overloads.
Which motor has highest no load speed?
Explanation: At no load, armature current tends to zero, flux φ tends to zero, where speed is inversely proportional to the flux, speed will tend to infinity. Thus, no load speed of DC series motor is highest.
Which DC motor has maximum self loading property?
Which DC motor has got maximum self-loading property? Explanation: A differentially compound DC motor, flux reduces so sharply at small increase in load at higher values of load.
Which motor is used in hand watches?
Both analog and stepped-movement quartz clocks use the Lavet-type stepping motor (see Quartz clock). Through miniaturization, it can be used in wristwatches and requires very little power, making a battery last for many years.