Which motor is variable speed motor?
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 any DC motor be variable speed?
A: 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.
Why DC series motor is called a variable speed drive?
From speed-current characteristic curve it is obvious that the series motor is a variable speed motor i.e., speed varies with the variation in line current. With the decrease in load on a dc series motor, the speed increases and may become dangerously high at very light loads.
Are variable speed motors AC or DC?
Variable frequency drives or alternating current (AC) motor adjustable speed drives. They are used in synchronous motors and both in wound-rotor and in squirrel-cage rotor asynchronous induction motors.
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 can a DC motor below base speed?
Speeds above the motor base (nameplate) speed are obtained by weakening the motor shunt field with a rheostat or electronically. Speeds below the motor base speed are obtained by weakening the generator field. This, in turn, lowers the generator voltage supplying the DC motor armature.
Which type of DC motor is used for variable speed control application?
4. Compound DC Motors. Compound DC motors or compound wound motors have both series and shunt field windings. These types of motors offer good starting torque, but they may have control problems in variable speed drive applications.
Can 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).
Which DC motor is preferred for constant speed?
DC Shunt-wound motor: This is an almost constant speed motor and its torque varies nearly as the current.
What is a variable speed motor called?
A variable speed drive (also known as a VSD, variable frequency drive, VFD, adjustable speed drive, inverter, converter or simply, ‘a drive’) is a device which is used to control the speed or torque generated by an electric motor.
Why is DC motor preferred over AC motor?
Because DC motors have higher starting torque compared to AC motors, they are preferred for applications like electrical traction. They are considered ideal for dealing with heavy loads for starting conditions in machines such as locomotives and cranes.
What’s better AC or DC?
DC power is significantly more energy efficient than AC power. DC motors and appliances have higher efficiency and power to size characteristics. … The greater efficiency resulting from recent developments in DC converter technology allows improvements in electricity delivery over long distances.