Electrical characteristics like voltage, frequency and phase of power supply should be consistent with the motor nameplate rating. A motor will operate satisfactorily on voltage within 10% of nameplate value, or frequency within 5%, or combined voltage and frequency variation not to exceed 10%.
What are the characteristics of electric motor?
Electric motor speed-torque characteristics may be classified into three main groups:
- Absolutely Hard (flat) Speed-Torque Characteristic: A characteristic exhibiting no change in speed with change in load torque. …
- Hard Speed-Torque Characteristic: …
- Soft Speed Characteristic:
Why are motor characteristics important?
Generally, three characteristic curves are considered important for DC motors which are, (i) Torque vs. armature current, (ii) Speed vs. … These are explained below for each type of DC motor. These characteristics are determined by keeping the following two relations in mind.
What is load characteristics of motor?
The motor load determines the operating point on the torque curve. While the motor torque and current may exceed 100% for a few seconds during starting, continuous operation above 100% can damage the motor. Any motor torque load above the breakdown torque will stall the motor.
What are the characteristics of induction motor?
Rotating Speed and Torque
2.40 shows the characteristics of induction motors. When a motor is designed in such a way that impedance of the aluminum conductor of the rotor is reduced, its efficiency is increased in a high-speed range.
What are the characteristics of three-phase induction motor?
The torque-speed characteristics of a three-phase induction motor is a straight line between the no-load and full-load operating points. The slope of the curve line depends upon the resistance of the rotor circuit i.e. the higher the rotor circuit resistance, the sharper the slope of the curve.
What is the characteristic of DC motor?
DC Motor Construction and Operation
A DC motor is comprised of a wound armature, commutator, brushes and magnets—all within a totally-enclosed housing. Rotation occurs when the magnetic field of the motor—created by the permanent magnets in the housing—interacts with the commutator through graphite or carbon brushes.
What is EMF and back emf?
Counter-electromotive force (counter EMF, CEMF), also known as back electromotive force (back EMF), is the electromotive force (voltage) that opposes the change in current which induced it. CEMF is the EMF caused by magnetic induction (see Faraday’s law of induction, electromagnetic induction, Lenz’s law).
What are the principal characteristics of a series De motor What are its uses?
From torque-current characteristic it is evident that series motor develops large starting torque to accelerate the heavy masses and from speed-current characteristic it is also evident that speed falls as the load increases, so series motor is automatically relieved from heavy excessive load, therefore, series motor …
What are load characteristics?
[′lōd ‚kar·ik·tə′ris·tik] (electronics) Relation between the instantaneous values of a pair of variables such as an electrode voltage and an electrode current, when all direct electrode supply voltages are maintained constant. Also known as dynamic characteristic.
What two important characteristics are possessed only by the synchronous type of motor?
Characteristics of Synchronous Motor are constant speed motors. The speed of the motor is decided by the number of poles and frequency. Compared to an induction motor, it is very sensitive to sudden changes of load. This causes a hunting of the rotor and finally leads to stability problems.
What are the characteristics of a cumulatively compounded DC motor?
Characteristics of Compound DC Motors
The shunt field winding of cumulative motors and their additional flux from series winding produces a large amount of flux which causes a large amount of torque at low speed. It means that motors such as cumulative run at a reasonable speed on light or even no-load conditions.
What are the characteristics of synchronous motor?
Main Features of Synchronous Motors
- Synchronous motors are inherently not self starting. …
- The speed of operation of is in synchronism with the supply frequency and hence for constant supply frequency they behave as constant speed motor irrespective of load condition.
What are characteristics of torque?
Torque is proportional to voltage squared and the current is proportional to the voltage. So, if the stator voltage is reduced the speed reduces and similarly if the stator voltage is increased the speed also increases.
What characteristic of an AC induction motor must be considered when changing the motor speed?
Key Characteristic: Running Speed
Two important characteristics of AC motors that need to be considered for any application are running speed and starting torque. Running speed is dependent on the power supply frequency, the number of motor poles and the amount of slip.