# Best answer: How can you reduce the RPM of a DC motor?

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## How do you change rpm on a DC motor?

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.

1. Flux Control Method. Due to the field winding, the magnetic flux varies in order to vary the speed of the motor. …
2. Armature Control Method. …
3. Voltage Control Method.

## How the speed of a DC motor can be increased or decreased?

The speed of rotation of an electric motor can be varied based on the following factors: Magnetic flux – By decreasing the flux, the speed of the motor can be increased. The flux can be changed by changing the current with a shunt field rheostat. … This increased torque causes the dc motor to increase in speed.

## How can we change the speed of a DC motor using PWM?

If such a signal is fed to a DC motor, we can change the speed of the motor by changing the duty cycle of the PWM signal. The change in pulse width is created by increasing the on-time (HIGH value) of the pulse while reducing the off-time (LOW value) by the same amount so that the frequency of the signal is constant.

## How do you control the torque of a DC motor?

To control DC motors torque, a DC drive will regulate armature current. The armature voltage is unregulated allowing the motor to operate at whatever speed is necessary to achieve the set current /torque level.

## What are the methods of speed control of DC shunt motor?

Speed control of Shunt motor

• Flux control method. It is already explained above that the speed of a dc motor is inversely proportional to the flux per pole. …
• Armature control method. …
• Voltage Control Method. …
• Flux control method. …
• Variable resistance in series with armature. …
• Series-parallel control.

## How can you increase or decrease the speed of rotation?

The speed of the rotation of the electric motor can be increased by changing the resistance of the circuit, by decreasing the resistance of the electric motor, there is the increase of the current then the current strength will increase.

## Which DC motor is preferred for constant speed?

Which D.C motor is preferred for machine tools? Explanation: DC shunt motor is a constant speed motor tool machine such as lathe machine requires being run at a constant speed.

## What is PWM DC motor speed control?

PWM (Pulse Width Modulation) One method that is often used for DC motor control using a microcontroller is Pulse Width Modulation (PWM) method. The speed of the electric motor depends on the modulator voltage. The greater the voltage, the faster the rotation of an electric motor.

## How do you control the speed of a single phase motor?

Is is possible to control the speed of an induction motor (single or three phase) by reducing the voltage. This will reduce the magnetizing current, flux, and thereby increase the slip, by essentially reducing the rating. Not all types of motors are designed to run with significant slip (e.g. more than 5%).

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## 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.

## Does PWM reduce torque?

Your PWM driver might add a bit of resistance to the circuit, reducing the current and torque a bit, but usually this isn’t significant compared to the resistance of the motor windings.

## What is rpm of DC motor?

DC controls adjust speed by varying the voltage sent to the motor (this differs from AC motor controls which adjust the line frequency to the motor). Typical no load or synchronous speeds for an AC fractional horsepower motor are 1800 or 3600 rpm, and 1000-5000 rpm for DC fractional hp motors.

## How can you control the speed of a permanent magnet on a DC motor?

As the magnetic field strength of a permanent magnet is fixed it cannot be controlled externally, field control of this type of DC motor cannot be possible. Thus permanent magnet DC motor is used where there is no need to control the speed of the motor (which is usually done by controlling the magnetic field).