What is the function of amplidyne?
An amplidyne comprises an electric motor which turns a generator on the same shaft. Unlike an ordinary motor-generator, the purpose of an amplidyne is not to generate a steady voltage but to generate a voltage proportional to an input current, to amplify the input in applications where high output power is required.
What is amplidyne and metadyne?
Amplidyne is a special purpose DC generator. A metadyne is a DC electrical machine including two pairs of brushes. It consists of a motor & a generator. It includes sets of brushes. It provides huge DC currents.
What is the function of metadyne?
A metadyne is a direct current electrical machine with two pairs of brushes. It can be used as an amplifier or rotary transformer. It is similar to a third brush dynamo but has additional regulator or “variator” windings.
Which one of the following is correct application of amplidyne?
The amplidyne is used in industry in high power servo and control systems, to amplify low power control signals to control powerful electric motors.
What happens to amplidyne when over compensated?
However, in the case of extreme overcompensation, undesirable self-excitation of the amplidyne i.e., spontaneous rise in voltage and load current at constant control current (or with the control circuit open) can occur.
What is load in dc motor?
The term load for a DC motor is based on its armature current . If rated current of an motor is 16 A . Then half load means at which the armature current is half its rated value which is 8 A . Similarly Quarter load is 4A and three fourth load is 12 A .
What is metadyne control system?
The main function of a metadyne is to change the input of stable voltage into a stable current and uneven voltage output. They are used to control large guns and controlling the speed of electric trains (underground). It can be also used as a rotary transformer/an amplifier.
What is Rosenberg generator?
The Rosenberg generator is normally used for train lighting. This generator is very much similar in construction as that of Metadyne generator. It also consists of four brushes located as shown in the Figure. The Rosenberg generator normally does not have the compensation winding.
What is the main advantage of a series motor?
Advantages of DC series motors:
Protection is very easy. It is cost-effective. Series wound motors can use for AC or DC supply so it is also known as universal motors. Compare with shunt motor DC series motor develop power for the same construction size.
How does a DC generator generate electricity?
A DC generator is an electrical machine whose main function is to convert mechanical energy into electricity. When the conductor slashes magnetic flux, an emf will be generated based on the electromagnetic induction principle of Faraday’s Laws.
What is the purpose of a DC generator that has been modified to function as an amplidyne?
An amplidyne is a special-purpose DC generator. It comprises an electric motor that turns a generator on the same shaft. It supplies large currents, precisely controlled, to the large motors used to drive heavy physical loads, such as gun turrets and missile launchers.
What is RPM of DC motor?
DC controls adjust speed by varying the voltage sent to the motor (this differs from AC motor controls which adjust the line frequency to the motor). Typical no load or synchronous speeds for an AC fractional horsepower motor are 1800 or 3600 rpm, and 1000-5000 rpm for DC fractional hp motors.
What are the 4 types of DC motor?
The DC motor uses DC current to transform electrical energy into mechanical energy. The main advantage of using this is that we can control the speed, and it occupies less space. There are 4 major types of DC motor.
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They are:
- Series DC Motor.
- Shunt/Parallel DC Motor.
- Compound DC Motors.
- Permanent Magnet DC Motor.
What is a cross field generators?
The cross-field machines are special DC machines having an additional set of brushes on the direct-axis or d-axis. This arrangement of brushes enables the use of armature MMF to provide most of the excitation and achieve high power gains.
Which generator is used in train?
Currently, most trains have power cars housing diesel generators, which supply electricity to coaches for various purposes including lighting, fans and air conditioning. Indian Railways now plans to introduce a new technology, known as “Head on Generation” (HOG), which is already in use worldwide.
What is cross field generator?
What is the limitation of series motor?
Disadvantages of DC Series Motor
Speed regulation in the series motor is quite poor. With the increase in the load speed of the machine decreases. (DC shunt motor maintains almost constant speed from no load to full load). DC series motor should always require to be loaded before starting the motor.
What is cogging in a motor?
Introduction. Cogging is an undesirable characteristic of some permanent magnet motor designs. It’s also known in stepper motors as ‘detent’ or ‘no current’ torque. Cogging torque is generated when the sides of the rotor teeth line up with the sides of the stator teeth within the motor.
Why are DC generators not used?
Dc machines are not very robust, they are expensive and are not longer much utilised. DC machines are almost discontinued. They cannot compete with AC machines. Its only advantage was (in the past) that a DC machine could be controlled to produce a high dynamic response.
What is the basic principle of A DC generator?
A DC generator operates on the principle of electromagnetic induction i.e. when the magnetic flux linking a conductor changes, an EMF is induced in the conductor.
What causes counter EMF in a DC motor?
When the armature of a DC motor rotates under the influence of the driving torque, the armature conductors move through the magnetic field and hence emf is induced in them as in a generator. The induced emf acts in opposite direction to the applied voltage V (Lenz’s law) and is known as Back EMF or Counter EMF (Eb).
How does commutator convert AC to DC?
Commutator converts the Alternating to direct current in a DC generator. The alternating current generated in the armature windings of the generator gets converted to direct current after it passes through the commutator and the brushes.
How RPM is calculated?
How to Calculate Motor RPM. To calculate RPM for an AC induction motor, you multiply the frequency in Hertz (Hz) by 60 — for the number of seconds in a minute — by two for the negative and positive pulses in a cycle. You then divide by the number of poles the motor has: (Hz x 60 x 2) / number of poles = no-load RPM.
What is torque of DC motor?
In a DC motor, a circumferential force (F) at a distance r which is the radius of the armature is acted on each conductor, tending to rotate the armature. The sum of the torques due to all the armature conductors is known as armature torque (τa).
Which DC motor is best?
Series wound DC motors are best for applications that require high startup torque, without the need for speed regulation. Like a shunt motor, as a load is applied to a DC series motor, the motor speed decreases, which reduces the back EMF and increases the net voltage.