The speed regulation of a DC motor is proportional to the resistance of armature. The lower the armature resistance, the better the speed regulation because of the armature current determines the torque produced by the motor if field excitation current is held constant.
What determines the speed of a DC motor?
Generally, the rotational speed of a DC motor is proportional to the EMF in its coil (= the voltage applied to it minus voltage lost on its resistance), and the torque is proportional to the current. Speed control can be achieved by variable battery tappings, variable supply voltage, resistors or electronic controls.
Which DC motor has poorest speed regulation?
The speed regulation of a permanent magnet DC motor is good ranging from 10 – 15% whereas for DC shunt motor it is somewhat less than 10 %. DC series motor has poor value of regulation.
What two factors determine the amount of torque developed by a DC motor?
What two factors determine the amount of torque developed by a DC motor? The strength of the magnetic field in the armature, and the strength of the magnetic field in the poles.
Why is it necessary to control the speed of a DC motor?
In mechanical system, speed varies with number of task so speed control is necessary to do mechanical work in a proper way. It makes motor to operate easily. Shunt motor is a special type of DC motor which runs at a constant speed. But using field and armature rheostat control method we can make it more versatile.
How do you change the speed of a DC motor?
Thus, the speed of a DC motor can control in three ways:
- By varying the flux, and by varying the current through field winding.
- By varying the armature voltage, and the armature resistance.
- Through the supply voltage.
What is the maximum speed of dc motor?
Why starters are required in a DC 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.
When the speed of DC motor is increased?
The speed of a dc motor is changed by changing the current in the field or by changing the current in the armature. When the field current is decreased, the field flux is reduced, and the counter emf decreases. This permits more armature current. Therefore, the motor speeds up.
What are the applications of DC motor?
Applications. DC motors are suitable for many applications – including conveyors, turntables and others for which adjustable speed and constant or low-speed torque are required. They also work well in dynamic braking and reversing applications, which are common in many industrial machines.
What are the two basic types of DC motor connections?
Main Types of DC Motors
- Permanent Magnet DC Motors. The permanent magnet motor uses a permanent magnet to create field flux. …
- Series DC Motors. In a series DC motor, the field is wound with a few turns of a large wire carrying the full armature current. …
- Shunt DC Motors. …
- Compound DC Motors.
How can a DC motor be made to operate at its base speed?
The speed of a DC motor can be controlled by applying variable voltage to the armature or field. … When full voltage is applied to the field and reduced voltage is applied to the armature, the motor operates below normal speed.
What determines the torque of a DC motor?
1 Answer. Torque of a motor is directly proportional to current. Therefore, the maximum torque a motor can produce is limited by the maximum current it can handle. The maximum steady state current a motor can handle is limited by the heat it can safely dissipate, which is proportional to the square of the current.
How can you reduce the speed of a DC motor?
If you want to reduce rpm without compromising speed regulation then use a voltage regulator or PWM controller to lower the motor voltage. If you also want higher torque then use a gearbox (which increases torque by the same proportion as it reduces shaft rpm).
What is meant by speed control of dc motor?
Often we want to control the speed of a DC motor on demand. This intentional change of drive speed is known as speed control of a DC motor. Speed control of a DC motor is either done manually by the operator or by means of an automatic control device.
How do you slow down a 12v DC fan?
Get a three 1.8 ohm 2 watt resistors, connect them in parallel and put them in series with your fan (put them in the air stream of the fan to help cool them). That should slow your fan down and reduce the load.