What are the advantages of parallel operation of alternator Mcq?
What are the conditions of parallel operation of alternators? The voltage of the incoming alternator must be same as the bus-bar voltage. The frequency of the incoming alternator must be same as the frequency of bus-bar voltage.
What are the advantages of alternator? Alternators have several advantages over direct-current generators (dynamos). Alternators are: Lighter, cheaper, and more rugged. Can provide useful charge at idle speed.
What happens to the power factor of an alternator operating in parallel with other alternators if its excitation is increased above the normal value of excitation? If the excitation of an alternator operating in parallel with other alternators is increased above its normal value of excitation, its power factor changes in the lagging direction and its current output increases with no appreciable change in its kW load.
What are the advantages of parallel operation of alternator Mcq? – Related Questions
Why do we need parallel operation?
Parallel operation of a transformer is necessary because of the following reasons are given below: It is impractical and uneconomical to have a single large transformer for heavy and large loads. In substations, the total load required may be supplied by an appropriate number of the transformer of standard size.
Which condition is not required for parallel operation of two alternator?
The phase sequence of the busbar voltages and the incoming machine voltage must be same. The busbar voltages and the incoming machine terminal voltage must be in phase.
Which instrument is used for parallel operation of alternator?
This can be done by adjusting the terminal voltage of incoming machine by changing the field current and make it equal to the line voltage of running system using voltmeters. First one is using a Synchroscope. It is not actually check the phase sequence but it is used to measure the difference in phase angles.
What is synchronization condition?
There are five conditions that must be met before the synchronization process takes place. The source (generator or sub-network) must have equal line voltage, frequency, phase sequence, phase angle, and waveform to that of the system to which it is being synchronized.
Which type of rotor is best for a turbo alternator?
Smooth cylindrical type rotor is generally used for high speed alternators or turbo alternators.
What is the operation principle of alternator?
An alternator operates on the same fundamental principle of electromagnetic induction as a DC generator. The working of an alternator is based on the principle that when the flux linking a conductor changes, an emf is induced in the conductor.
What is the working of alternator?
An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.
How does excitation affect power factor?
A change in the excitation, thus, affects only the power factor of its output. This reduces the terminal voltage slightly, so let the excitation of the first alternator be increased so as to bring the terminal voltage back to its original value.
What basis the load is shared by the two alternators after Synchronised?
When several alternators are required to run in parallel, it probably happens that their rated outputs differ. In such cases it is usual to divide the total load between them in such a way that each alternator takes the load in the same proportion of its rated load in total rated outputs.
What is the effect of dc excitation on power factor?
When the excitation of a three-phase synchronous motor taking a constant power, is varied, it changes the operating power factor of the motor. For a constant input power and terminal voltage only increase in power factor, causes a decrease in armature current and vice versa.
What is parallel operation?
Parallel operation is the connec- tion of two or more power sources of the same size and output volt- age to obtain a higher output cur- rent. When connecting in parallel the outputs must be connected together keeping polarity in mind. The output voltage remains the same, but the current increases.
How are two generators operated in parallel?
Each individual generator operates at its own specified engine speed and frequency. When individual generators are coupled together, their engine speeds are locked into the overall speed of the entire system. In a parallel system, the entire load is shared by all generators.
What are the advantages of parallel operation of two or single phase transformers?
Advantages of Transformer Parallel Operation
Generally electrical power transformer gives the maximum efficiency at full load. If we run numbers of transformers in parallel, we can switch on only those transformers which will give the total demand by running nearer to its full load rating for that time.
What are the condition for parallel operation Mcq?
Conditions for parallel operation of Transformers: The line voltage ratio of two transformers must be equal. The per-unit impedance of each transformer should be equal and they should have the same ratio of equivalent leakage reactance to the equal resistance (X/R) The transformers must have the same polarity.
When two alternators are running in parallel their KVA load share is changed by changing their?
33. When two alternators are running in parallel their kVAR load share and kW load share are changed by changing their. Answer: (c) excitation, driving torque respectively.
Can two alternators charging one battery?
It will work just fine. When your batteries are low both alternators will charge the bank. as they start to top off, one alternator will probably start to ramp down it’s charge rate sooner than the other due to the regulators having small differences.
What is the name of the instrument used to indicate the correct time for parallel operation of alternators?
Definition: The synchroscope is a device which shows the correct instant at which the two systems are synchronised. The terms ‘synchronize’ means the machines of equal frequency and voltage are operating parallel to each other.
What is Synchroscope method?
In AC electrical power systems, a synchroscope is a device that indicates the degree to which two systems (generators or power networks) are synchronized with each other. Synchroscopes measure and display the frequency difference and phase angle between two power systems.
Why is synchronization needed?
The need for synchronization originates when processes need to execute concurrently. The main purpose of synchronization is the sharing of resources without interference using mutual exclusion. The other purpose is the coordination of the process interactions in an operating system.
Which kind of rotor is most suitable for alternators which are designed to run at high speed?
177. What kind of rotor is most suitable for turbo-alternators which are designed to run at high speed? 178. The power developed in the alternator having salient type rotor is less than of having non-salient pole.
What is the formula for rotor turns per phase?
8. What is the formula for rotor turns per phase? Explanation: Firstly, the winding factor for stator is obtained along with the winding factor for stator. Next the ratio of the rotor voltage per phase to the stator voltage per phase.