Electric Generators

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working principle and use of Generator

Generator is a machine that converts mechanical energy into electrical energy. It works based on principle of faraday law of electromagnetic induction. The faradays law states that whenever a conductor is placed in a varying Magnetic Field, EMF is induced and this induced EMF is equal to the rate of change of flux linkages. This EMF can be generated when there is either relative space or relative time variation between the conductor and magnetic field.

Working of Generators

Generators are basically coils of electric Conductors, normally copper wire, that are tightly wound onto a Metal core and are mounted to turn around inside an exhibit of large magnets. An electric conductor moves through a magnetic field, the Magnetism will interface with the electrons in the conductor to induce a flow of electrical current inside it.

The conductor coil and its core are called the armature, connecting the armature to the shaft of a mechanical power source, for example an motor, the copper conductor can turn at exceptionally increased speed over the magnetic field.

The point when the generator armature first starts to turn, then there is a weak magnetic field in the iron pole shoes. As the armature turns, it starts to raise voltage. Some of this voltage is making on the field windings through the generator regulator. This impressed voltage builds up stronger winding current, raises the strength of the magnetic field. The expanded field produces more voltage in the armature. This, in turn, make more current in the field windings, with a resultant higher armature voltage. At this time the signs of the shoes depended on the direction of flow of current in the field winding. The opposite signs will give current to flow in wrong direction.

Types of Generators:

  • AC generators
  • DC generators

 

AC Generators

These are also called as alternators. It is the most important means of producing electrical power in many of the places since now days all the consumers are using AC. It works based on principle of the electromagnetic induction. These are of two types one is induction generator and other one is synchronous generator. The induction generator requires no separate DC excitation, regulator controls, frequency control or governor. This concept takes place when conductor coils turn in a magnetic field actuating a current and a voltage. The generators should run at a consistent speed to convey a stable AC voltage, even no load is accessible.

Synchronous generators are large size generators mainly used in power Plants. These may be rotating field type or rotating armature type. In rotating armature type, armature is at rotor and field is at stator. Rotor armature current is taken through slip rings and brushes. These are limited due to high wind losses. These are used for low power output applications. Rotating field type of alternator is widely used because of high power generation capability and absence of slip rings and brushes.

It can be either 3 phase or two phase generators. A two-phase alternator produces two completely separate voltages. Each voltage may be considered as a single-phase voltage. Each is generated voltage completely independent of the other. The three-phase alternator has three single-phase windings spaced such that the voltage induced in any one phase is displaced by 120º from the other two. These can be connected either delta or wye connections. In Delta Connection each coil end is connected together to form a closed loop. A Delta Connection appears like the Greek Letter Delta (Δ). In Wye Connection one end of each coil connected together and the other end of each coil left open for external connections. A Wye Connection appears as the letter Y.

Advantages of AC Generator

  • These Generators are generally maintenance free, because of absence of brushes.
  • Easily step up and step down through transformers.
  • Transmission link size might be thinner because of step up feature
  • Size of the generator relatively smaller than DC machine
  • Losses are relatively less than DC machine
  • These Generator breakers are relatively smaller than DC breakers

DC Generators

DC generator is typically found in off-grid applications. These generators give a seamless power supply directly into electric storage devices and DC power grids without novel equipment. The stored power is carries to loads through dc-ac converters. The DC generators could be controlled back to an unmoving speed as batteries tend to be stimulating to recover considerably more fuel.

Permanent magnet DC generators do not require external field excitation because it has permanent magnets to produce the flux. These are used for low power applications like dynamos. Separately-excite DC generators requires external field excitation to produce the magnetic flux. We can also vary the excitation to get variable output power. These are used in electro plating and electro refining applications. Due to residual magnetism present in the poles of the stator self-excited DC generators can able to produce their own magnetic field ones it is started. These are simple in design and no need to have the external circuit to vary the field excitation. Again these self-excited DC generators are classified into shunt, series, and compound generators.

Advantages of DC Generator

  • Mainly DC machines have the wide variety of operating characteristics which can be obtained by selection of the method of excitation of the field windings.
  • The output voltage can be smoothed by regularly arranging the coils around the armature .This leads to less fluctations which is desirable for some steady state applications.
  • No shielding need for radiation so cable cost will be less as compared to AC.

 

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Electric generators are machines that convert mechanical energy into electrical energy. They are used in a wide variety of applications, including power generation, motor drive, and uninterruptible power supply (UPS).

There are two main types of electric generators: synchronous generators and induction generators. Synchronous generators produce alternating current (AC) electricity, while induction generators produce direct current (DC) electricity.

Synchronous generators are the most common type of electric generator. They are used in power plants, large industrial facilities, and other applications where large amounts of AC electricity are needed. Synchronous generators are typically powered by steam turbines, gas turbines, or water turbines.

Induction generators are used in smaller applications, such as portable generators and wind turbines. They are also used in some motor drives. Induction generators are typically powered by electric motors.

Electric generators are made up of a stator and a rotor. The stator is the stationary part of the generator, and the rotor is the rotating part. The stator and rotor are made up of coils of wire that are wound around a core. The core is typically made of iron or steel.

When the rotor turns, it creates a magnetic field. This magnetic field induces an electric current in the stator coils. The electric current is then used to power electrical loads.

Electric generators are typically regulated by a device called an exciter. The exciter supplies power to the rotor coils, which creates the magnetic field that induces the electric current in the stator coils. The exciter is typically controlled by a feedback system that maintains a constant output voltage from the generator.

Electric generators are typically cooled by a fan or a water-cooling system. The fan or water-cooling system removes heat from the generator, which prevents it from overheating.

Electric generators require regular maintenance to ensure that they operate safely and efficiently. Preventive maintenance includes tasks such as changing oil, cleaning filters, and inspecting bearings. Corrective maintenance is performed to fix problems that have been identified.

Common problems with electric generators include:

  • Bearing failure
  • Stator winding failure
  • Rotor winding failure
  • Exciter failure

Troubleshooting procedures for electric generators vary depending on the type of generator and the problem that has been identified. However, some general troubleshooting procedures include:

  • Checking the generator’s output voltage
  • Checking the generator’s input voltage
  • Checking the generator’s coolant level
  • Checking the generator’s oil level
  • Checking the generator’s bearings
  • Checking the generator’s stator windings
  • Checking the generator’s rotor windings
  • Checking the generator’s exciter

Electric generators must be operated safely to prevent injury or death. Some safety precautions that should be taken when operating electric generators include:

  • Wearing personal protective equipment (PPE), such as safety glasses and gloves
  • Disconnecting the generator from the power grid before performing maintenance
  • Keeping the generator clean and free of debris
  • Inspecting the generator regularly for signs of wear or damage
  • Following the manufacturer’s instructions for safe operation

Electric generators are used in a wide variety of applications, including:

  • Power generation
  • Motor drive
  • Uninterruptible power supply (UPS)
  • Frequency converter
  • Other applications

Power generation is the most common application for electric generators. Electric generators are used to generate electricity for homes, businesses, and industries.

Motor drive is another common application for electric generators. Electric generators are used to power motors in a variety of applications, such as pumps, fans, and conveyors.

Uninterruptible power supply (UPS) is a system that provides power to critical loads during a power outage. UPS systems typically use electric generators to provide power during an outage.

Frequency converter is a device that changes the frequency of an electric current. Electric generators are sometimes used as frequency converters.

Electric generators are also used in a variety of other applications, such as welding, lighting, and telecommunications.

What is a motor?

A motor is a machine that converts electrical energy into mechanical energy.

What are the different types of motors?

There are many different types of motors, but the most common are:

  • DC motors: These motors are powered by direct current (DC) electricity. They are often used in small appliances and tools.
  • AC motors: These motors are powered by alternating current (AC) electricity. They are often used in large appliances and machines.
  • Synchronous motors: These motors have a rotating magnetic field that is synchronized with the electric current that powers them. They are often used in large motors that require precise speed control.
  • Induction motors: These motors have a rotating magnetic field that is induced by the electric current that powers them. They are often used in small motors that do not require precise speed control.

How does a motor work?

A motor works by converting electrical energy into mechanical energy. This is done by using a magnetic field to create a force that turns a shaft. The shaft is then connected to the load that the motor is powering.

What are the advantages of using a motor?

There are many advantages to using a motor. Motors are efficient, reliable, and easy to use. They can be used to power a wide variety of devices, from small appliances to large machines.

What are the disadvantages of using a motor?

Motors can be expensive, and they can be noisy. They also require regular maintenance.

How can I choose the right motor for my needs?

When choosing a motor, it is important to consider the following factors:

  • The type of load that the motor will be powering
  • The amount of power that the motor will need
  • The speed that the motor will need to operate at
  • The Environment in which the motor will be used

Where can I buy a motor?

Motors can be purchased from a variety of sources, including:

  • Hardware stores
  • Electrical supply stores
  • Online retailers

How much does a motor cost?

The cost of a motor will vary depending on the type, size, and power of the motor. Motors can range in price from a few dollars to several thousand dollars.

How do I install a motor?

The installation of a motor should be done by a qualified electrician. The electrician will be able to select the correct motor for your needs and install it safely and correctly.

How do I maintain a motor?

Motors should be regularly maintained to ensure that they operate safely and efficiently. The maintenance schedule for a motor will vary depending on the type and size of the motor. However, most motors should be cleaned and lubricated on a regular basis.

What are the safety precautions that I should take when using a motor?

When using a motor, it is important to take the following safety precautions:

  • Always read and follow the manufacturer’s instructions.
  • Make sure that the motor is properly installed and grounded.
  • Do not overload the motor.
  • Keep the motor clean and free of debris.
  • Disconnect the motor from the power source before servicing or cleaning it.

What are the common problems with motors?

The most common problems with motors are:

  • Overheating
  • Bearing failure
  • Electrical problems

If you experience any problems with your motor, it is important to have it serviced by a qualified electrician.

Sure, here are some MCQs without mentioning the topic Electric Generators:

  1. A device that converts mechanical energy into electrical energy is called a:
    (A) Motor
    (B) Generator
    (C) Transformer
    (D) Battery

  2. The principle of operation of a generator is based on the:
    (A) Law of conservation of energy
    (B) Law of electromagnetic induction
    (C) Law of conservation of momentum
    (D) Law of conservation of charge

  3. The main component of a generator is the:
    (A) Armature
    (B) Stator
    (C) Rotor
    (D) Field coil

  4. The frequency of the output voltage of a generator is determined by the:
    (A) Speed of the rotor
    (B) Number of poles on the stator
    (C) Number of turns in the armature winding
    (D) All of the above

  5. The output voltage of a generator is increased by:
    (A) Increasing the number of turns in the armature winding
    (B) Increasing the speed of the rotor
    (C) Increasing the number of poles on the stator
    (D) All of the above

  6. The output voltage of a generator is decreased by:
    (A) Decreasing the number of turns in the armature winding
    (B) Decreasing the speed of the rotor
    (C) Decreasing the number of poles on the stator
    (D) All of the above

  7. The efficiency of a generator is determined by the:
    (A) Copper losses
    (B) Iron losses
    (C) Mechanical losses
    (D) All of the above

  8. The power factor of a generator is determined by the:
    (A) Load current
    (B) Load voltage
    (C) Load power
    (D) All of the above

  9. The regulation of a generator is determined by the:
    (A) Change in output voltage with change in load current
    (B) Change in output voltage with change in speed
    (C) Change in output voltage with change in temperature
    (D) All of the above

  10. The harmonics of a generator are determined by the:
    (A) Number of poles on the stator
    (B) Number of turns in the armature winding
    (C) Saturation of the core
    (D) All of the above