Compound Motors

Brushless DC electric motor and Switched reluctance motor. The smaller motor is rated at W 0. Yes, I repeat the title because and as we said before, both long and short shunt compound motor can be subdivided according to the excitation or nature of compounding to: Advantages of a brushed DC motor include low initial cost, high reliability, and simple control of motor speed.

A simple DC motor has a stationary set of magnets in the stator and an armature with one or more windings of insulated wire wrapped around a soft iron core that concentrates the magnetic field. Yeadon, Alan W. For example, if a resistor with the same resistance as the field winding is switched in parallel with it, half of the armature current will now low through the resistor and half will low through the field.

The mechanical power developed by the armature of a d. Handbook of small electric motors. In this type of motor, negative terminal of the shunt field is connected to the positive terminal of the armature.

Coilgun Railgun Superconducting machine. We said before that compound motor divided according to the connection of field winding with respect to the armature winding to two major types: To convert the machine into the equivalent series version, the field coils need to be made from much thicker conductor, since they have to carry the armature current of 50 A, rather than the 2. A series motor has very high starting torque and is commonly used for starting high inertia loads, such as trains, elevators or hoists.

Electrical engineer's reference book. Disadvantages include high initial cost, and more complicated motor speed controllers. The shaft torque Tsh is less than armature torque Ta due to stray losses. Compound Interpole Motors Cumulative Compound Motors In cumulative compound motors, the polarity of the shunt winding is such that it adds to the series fields.

Compound DC Motors

Compensating windings in series with the armature may be used on large motors to improve commutation under load. Briefly, we can say that Dc compound motor is a combination of both a shunt wound Dc motor and series wound Dc motor which means that compound motor has the advantage of high starting torque and efficient speed regulation so it can be used in industrial applications include: For brushes intended to carry more than an ampere or two, a flying lead will be molded into the brush and connected to the motor terminals.

Advantages of brushless motors include long life span, little or no maintenance, and high efficiency. By varying the firing angle, and hence the proportion of each cycle for which the triac conducts, the voltage applied to the motor can be varied to provide speed control. If external mechanical power is applied to a DC motor it acts as a DC generator, a dynamo.

The interpole prevents the armature and brushes from arcing due to the buildup of magnetic forces. The current is 50 A, the resistance is 0. A typical torque-speed characteristic in the field-weakening region is shown by the line cd in Figure 3. Secondly, if a multicell battery is used to supply the motor, the cells may be switched progressively from parallel to series to give a range of Figure 3. The cumulative compound motor is one of the most common DC motors because it provides high starting torque and good speed regulation at high speeds.

As a result the motor speed reduces as the load increases shown in the fig above. In cumulative compound motors, the polarity of the shunt winding is such that it adds to the series fields. Which of the following d. When the load is increased, its speed is reduced drastically. This combination presents us the double advantage of having the torque characteristics of a series motor and the constant speed characteristic of a shunt motor in one compound wound motor.

Squirrel Cage Induction Motor: In fact any d. Since the armature voltage and the field direction reverse at the same time, torque continues to be produced in the same direction. For small load current and hence for small armature current change in back emf Eb is small and it may be neglected. We saw some examples of applications of DC motors also above. That is why a series motor should never be started without some mechanical load.