Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Q. Explain about Elementary Direct-Current Machines?
A preliminary discussion of dc machines, including Equations. The location of the brushes on the commutator arrangement connected to the armature winding ensures that the rotor and stator mmf axes are at all times at right angles to one another, as shown in Figure. The expression for torque given by Equation is applicable to the dc machine, provided the constant K is adjusted for the nonsinusoidal mmf distributions and sin δ is made equal to unity. Not only are the conditions for constant torque fulfilled, but also the condition for maximum torque and hence for maximum energy conversion is satisfied, since δ = ± π/2, depending upon whether generator or motor action occurs for a given direction of rotation.
Since both armature and field circuits carry direct current in the case of a dcmachine, they can be connected either in series or in parallel. When the armature and field circuits are connected in parallel, the machine is known as a shunt machine. In the shunt machine, the field coils are wound with a large number of turns carrying a relatively small current. When the circuits are connected in series, the machine is known as a series machine. The field winding in the series machine carries the full armature current and is wound with a smaller number of turns. A dc machine provided with both a series-field and a shunt-field winding is known as a compound machine. In the compoundmachine, the series fieldmay be connected either cumulatively, so that itsmmf adds to that of the shunt field, or differentially, so that the mmf opposes. The differential connection is used very rarely. The voltage of both shunt and compound generators (or the speed, for motors) is controlled over reasonable limits by means of a field rheostat in the shunt field. The machines are said to be self-excited when the machine supplies its own excitation of the field windings, as in the cases just defined. The field windings may be excited separately from an external dc source, however. A small amount of power in the field circuit can control a large amount of power in the armature circuit. The dc generator may then be viewed as a power amplifier.
how to sort three number in descending order and display on seven segment
Background of Energy Conservation As a thumb rule, the energy needs of a country are about 1.5 times its GDP or the economic growth rate. India's projected growth rate up to
Explain the purpose of the global descriptor table register. The GDTR stand for global descriptor table register and IDTR stand for interrupt descriptor table register conta
How do you size power factor units at 11kV
WHAT IS THE FUNCTION OF DELAY LINE IN CRO
Masking As we know the MASJ is used to cover some part of our face which we want to hide and to show other part of the face which we want to show. Similarly the
single phase voltage source inverter complete circuit
What are advantages of segmentation ? However because the segment register is 16 bit broad and the memory requires 20 bits for an address the 8086 appends 4 bits segment reg
Q. What is Barkhausen criterion? Why is the value of Ab kept slightly greater than 1? The condition |Ab| = 1 is called the Barkhausen criterion. It implies that when |Ab| = 1,
advantages and disadvantages of thevenin theorem
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd