1. Which of the following motor is used where high starting torque and wide speed range control is required? Explanation: DC series motor gives the maximum starting torque at starting. With the help of Ward Leonard speed control method various speeds are also available.
Which motor is used for high starting torque and high speed?
Universal motors have high starting torque, can run at high speed, and are lightweight and compact. They are commonly used in portable power tools and equipment, as well as many household appliances. They’re also relatively easy to control, electromechanically using tapped coils, or electronically.
Which applications require high starting torque?
- Eddy Current drives operate across a wider speed range.
- No need for external cooling fans.
- No need for oversizing the motor.
- Full range of horsepower options.
- Simple-to-use controllers.
22 июн. 2020 г.
Why is high starting torque required?
Locked Rotor or Starting Torque
The Locked Rotor Torque or Starting Torque is the torque an electrical motor develops when starting at zero speed. A high Starting Torque is more important for application or machines hard to start – like positive displacement pumps, cranes etc.
What is the starting torque of synchronous motor?
A synchronous motor with only a field winding carrying a direct current would not be self-starting. At any speed other than synchronous speed, its rotor would experience an oscillating torque of zero average value as the rotating magnetic field repeatedly passes the slower moving rotor.
Which motor is used for high torque?
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.
What is a starting torque?
Starting torque is the torque transferred by the shaft coupling during run-up (see Start-up process). It is calculated based on the ratio of power (P) to angular velocity (ω) and is represented as a rotational speed function.
How do you increase the torque of a motor?
If you want to adjust the output torque within the rated torque range, you can usually adjust the input voltage or the amount of excitation current. If the DC motor has been set, the torque can only be increased by the speed reducer, which can be multiplied or even increased by a thousand times.
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. It is advisable that motor should not be used beyond some load value, as it may damage itself by self-loading. 5.
Which motor has high starting current?
Starting current of induction motor is as high as 5 to 7 times the normal full load current. Therefore different starting of induction motor, methods such as (star delta starter, auto transformer starter and other starting methods) are employed in order to reduce the high starting currents of induction motor.
How much torque does a 1 hp motor have?
The definition of 1 Horsepower is displacing 1 lb. 33,000 ft. in one minute or 33,000 lb-ft / minute.
Why electric motors have more torque?
The benefit of using an electric motor to power a car is that it can help drivers reach maximum torque from 0 RPM. This is because electric motors use an electric current, which moves through a magnetic field and creates the force necessary to rotate the armature and get the car moving.
What is pull out torque?
The maximum torque that can be applied to a motor operating at a given speed without losing synchronism.
How do you know if a motor is synchronous?
Synchronous motor is a motor that operates at synchronous speed, i.e. speed of the rotor is equal to the stator speed of the motor. It follows the relation N = NS = 120f/P, where N is the rotor speed and Ns is the synchronous speed.
Why the speed of synchronous motor is constant?
Why does a synchronous motor rotate at a constant speed? The stator magnetic field rotates at synchronous speed (which depends upon the frequency of supply) and hence the rotor follows it and rotates at synchronous speed as well. The stator is excited from supply which produces a rotating magnetic field in the air gap.
Why the synchronous motor is not self starting?
Above a certain size, synchronous motors are not self-starting motors. This property is due to the inertia of the rotor; it cannot instantly follow the rotation of the magnetic field of the stator. … Once the rotor nears the synchronous speed, the field winding is excited, and the motor pulls into synchronization.