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How do you vary the speed of a motor?
Thus, the speed of a DC motor can be controlled in three ways:
- By varying the supply voltage.
- By varying the flux, and by varying the current through the field winding.
- By varying the armature voltage, and by varying the armature resistance.
What affects the speed of a motor?
The rotating speed of an electric motor depends on two factors: its physical construction, and the frequency (Hz) of the voltage supply.
Which motor is variable speed?
Variable speed drives (VSDs), also called variable frequency drives, are a valuable tool for the energy manager. Typically the VSD system consists of a three-phase AC induction motor and a variable frequency power supply.
Can you vary the speed of an AC motor?
Although they are constant speed devices, AC motor speeds can vary if the frequency, input voltage, or the windings that make the motor rotate are changed. A common and efficient means of changing a motor’s speed is to vary the frequency by use of an inverter as the power source.
How do you slow down an AC motor?
AC motors are constant speed devices but their speed can vary if you change the input voltage or frequency or the windings that make the motor rotate. The most common and efficient way of changing the speed is to vary the frequency by using an inverter as the power supply.
Does voltage increase motor speed?
Input Voltage: For a fixed load, the speed of the motor is affected by the applied voltage. Increase in voltage = increase in speed. Load Torque: For a fixed voltage, the speed of the motor is inversely affected by the load. Increase in load torque = decrease in speed.
Can any DC motor be variable speed?
In general if you don’t do anything special to it, a DC motor will have variable speed. The main factors are the DC voltage applied to the armature coil and the amount of torque load you are trying to drive. In order to make it into a constant speed DC motor you have to have some sort of electronic feedback.
Can I put a VFD on any motor?
Output voltages are available for VFDs to match almost any existing motor voltage. However, very few, if any, VFDs have a direct 13,800-volt output for very high-voltage motors. For these cases, using a step-up transformer on the output of the VFD is often necessary to match the motor voltage.
How do you increase the speed of an AC motor?
You increase the speed by increasing the frequency. If a motor base speed is 60 Hz, raising the frequency to 120 Hz will double the speed of the motor. However, if you do not keep the volt to hertz ratio constant, you will cause the motor windings to heat up.
Does speed affect voltage?
To understand this relationship between voltage and speed, let’s look at a typical brushed dc motor circuit. Back to the original question: how does voltage affect speed? From the analysis above, we can see that when the load (torque) on the motor is constant, speed is directly proportional to supply voltage.
What makes electric motor faster?
One easy way to make the motor run faster is to add another magnet. Hold a magnet over the top of the motor while it is running. As you move the magnet closer to the spinning coil, one of two things will happen. Either the motor will stop, or it will run faster.
How do you slow down an electric 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).
How can I change the speed of my electric motor?
The inverter controls will vary the frequency supplied to the motor and the motor speed will vary accordingly. Add a variable resistance in the motor circuit to reduce the voltage across the main winding if an inverter is too costly and accurate speed control is not required.
What happens to the speed of a motor when the load varies?
If the load varies, the speed changes. If the load drops to zero, the motor goes to full speed. Without a load, there is no speed variation. Increasing the motor slip causes increased power to be lost in the rotor. Motors that use this speed control method are generally designed for this type of use.
How is the speed of an AC motor determined?
AC motors are unique because they are built to run at specific speeds regardless of their design or manufacturer. The speed of an AC motor is dependent on the number of poles it has and the line frequency of the power supply, not on it’s voltage. Common AC motor units are constructed with either two or four poles.
Why does a DC motor have a maximum speed?
The number of wire turns in an armature, the operating voltage of the motor, and the strength of the magnets all affect motor speed. If a DC motor is running on a 12 V battery, that is the maximum voltage available to the unit and the motor will only be able to perform at a speed rated for 12 V. If the battery is low and supplying less voltage,