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.
Q. Illustrate Power Semiconductor Devices? Since the advent of the first thyristor or silicon-controlled rectifier (SCR) in 1957, tremendous advances have been made in power se
Ginny Jones currently works as the VP-Product Strategy for a well-established enterprise software company. She and her friend, Tom Robinson, currently CFO at a competing firm (and
Ask quA 380-V, 15-hp, 50-Hz, four-pole, Y-connected wound-rotor induction motor has the following impedances in ohms per phase referred to the stator circuit: R1= 0.453? R2= 0.24
Explain Medium length lines? Medium length lines cover lines in the range of 50 to 150 miles (80 to 240 km). Due to the increased length of the line, the shunt capacitance of t
Consider a colloidal suspension of latex particles confined between two plates. The plates are charged, so there is an electric potential difference V between them (as shown). The
You have been given a DC motor to characterize. What three measurements are required in order to develop the torque-speed curve and the acceleration curve for the unloaded motor?
High Level Language ( third Generation Language ) The difficulties of low level languages are overcome by high level languages. In assembly language mnemonics were used
I want to do programming in PIC controller and it needs to be done on particular development board.
Q. Digital controller for a steam-turbine driven generator? Figure illustrates the basic elements of a minicomputer system in terms of a block diagram for speed and voltage con
What do you understand by ASSUME assembler directive? ASSUME: This directive will be utilized to map the segment register names along with memory addresses. The Synta
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