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. Explain working of Resistance-capacitance coupled Amplifiers? Resistance-capacitance (RC)-coupled Amplifiers : The following figure illustrates the most widely used method
Q. Explain Common Emitter Circuit With The Help Of A Circuit Diagram? Most transistor circuits have the emitter,rather than the base,as the terminalcommon to both input and out
MVI Move Immediate Instruction This form of the instruction is used to copy 8bit data ( specified in the instruction ) directly into the register or memory pointed by
Q. What layers are covered under end to end layer connectivity? Layers 4-7 of ISO-OSI reference model communicate with peer entities in end systems. In intermediate systems,th
Consider the magnetic circuit of Figure with an air gap, while neglecting leakage flux. Correct for fringing by adding the length of the air gap l g = 0.1 mm to each of the other
Detection and Handling of Gas Leakage : If you are using a toxic gas or have a store for it you must have some devices to indicate the leakage, if any. Though numerous monitoring
i have an assignment. please help me.
1. For the flyback converter operating in the discontinuous "current" (flux) mode, derive an expression for the time at which the magnetizing current returns to zero. 2. A forwa
Q. (a) A balanced wye-connected load with per-phase impedance of 20 + j10 is connected to a balanced 415-V, three-phase supply through three conductors, each of which has a series
An industrial plant consumes 500 kWat a lagging power factor of 0.6. (a) Find the required kVA rating of a synchronous capacitor to improve the power factor to 0.9. (b) If a
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