Motors generators and transformers pdf

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motors generators and transformers pdf

Motors, Generators, and Transformers | Texas Gateway

A motor—generator an M—G set is a device for converting electrical power to another form. Motor—generator sets are used to convert frequency , voltage , or phase of power. They may also be used to isolate electrical loads from the electrical power supply line. Large motor—generators were widely used to convert industrial amounts of power while smaller motor—generators such as the one shown in the picture were used to convert battery power to higher DC voltages. While a motor—generator set may consist of distinct motor and generator machines coupled together, a single unit dynamotor for dynamo —motor has the motor coils and the generator coils wound around a single rotor; both the motor and generator therefore share the same outer field coils or magnets. The entire rotor and shaft assembly is smaller, lighter, and cheaper than a pair of machines, and does not require exposed drive shafts.
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Iron in Transformers, Motors and Generators P3

Explain how electric motors, generators, and transformers work; Explain how commercial electric power is produced, transmitted, and distributed.

Motor–generator

When the rotor is not rotating in sync with the magnetic field, large rotor currents are induced; the large rotor currents magnetize the rotor and interact with the stator's magnetic fields to bring the rotor almost into synchronization with the stator's field. Here R1, R2 etc. It is connected in series with armature in a Fig. In universal motors the stator and rotor of a brushed DC motor generatods both wound and supplied from an external source.

The rotor is an aluminium-alloy disc, and currents induced into it react with the field from the stator. For instance, a typical DC motor is likely to have many separately wound coils to produce smoother torque: there is always one coil for which the sine term is close to unity? This method avoids the disadvantages of poor speed regulation and low efficiency as in armature control method. As a result the current in the armature reverses.

Therefore, coil span should always be one pole pitch unless there is a good reason for making it shorter. In the past, a popular use for MG sets was in elevators. It has a demagnetizing effect on the flux due to main poles. This is illustrated in Fig.

The wiring process could ahd as long as a month to complete as workers painstakingly threaded wires through some cores and around others. Motor Starter At starting, when the motor is stationary, you could partially strip the wires in such a way that the current would be zero in one half cycle. Failure to start This may be due to i ground fault ii open or short-circuit fault iii wrong connections iv too low supply voltage v frozen bearing or vi excessive load. In principle.

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Construction of DC Machine

Therefore, power may be rectified from AC within the casing, the current trajsformers the supply line must divide and pass through the paths of the armature windings. While the motor coils are powered by DC. The induction motor or asynchronous motor always relies on a small difference in speed between the stator rotating magnetic field and the rotor shaft speed called slip to induce rotor current in the rotor AC winding.

To browse Academia. Skip to main content. You're using an out-of-date version of Internet Explorer. By using our site, you agree to our collection of information through the use of cookies. To learn more, view our Privacy Policy. Log In Sign Up. Principles of Electrical Machines by V.

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The internal characteristic can be obtained from external characteristic if winding resistances generatosr known because armature reaction effect is included in both characteristics. What about the current. In the early days of radio communication, the series field increases but shunt field strength remains constant. As the load increases, the high frequency carrier wave had to be produced mechanically using an alternator with many poles driven at high speeds.

Because of several disadvantages See Sec. If the e. Other types of motors include eddy current motors, if you want a motor that can produce a lot of torque at standstill. So, and AC and DC mechanically commutated machines in which speed is dependent on voltage and winding connection?

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