Table of Contents
What is the effect of the speed of a generator on its frequency?
The formula shows that frequency is directly proportional to the synchronous speed of the generator. This means that a higher frequency gives a higher speed and a lower frequency gives a lower speed.
What could be the result of the prime mover speed is too high?
As a prime mover power increases a load angle of 90° is eventually reached. Beyond this point further increases in mechanical input power cause the electrical power output to decrease. The surplus input power acts to further accelerate the machine and it is said to become unstable.
How do I increase the frequency of my alternator?
Since the number of poles are fixed for an alternator the only way to adjust the frequency is by adjusting the speed RPM of the alternator. ALTERNATOR FREQUENCY depends upon the speed of rotation and the number of pairs of rotor poles.
What causes over frequency in a generator?
Over-frequency is most often the result of an instantaneous load reduction when the generator is synchronized to the system, or from excessive turbine torque when the generator is in the open-circuit condition before synchronization with the grid.
What is frequency droop?
Droop speed control is a control mode used for AC electrical power generators, whereby the power output of a generator reduces as the line frequency increases. It is commonly used as the speed control mode of the governor of a prime mover driving a synchronous generator connected to an electrical grid.
Why does frequency drop when load increases?
when the load increased beyond the generated power,the speed of the generating unit decreases(Speed here is nothing but the speed of the generator). This reduction in the generator speed causes drop in the frequency. Hence when load increases,speed of the generator decreases and it causes drop in the frequency.
What happens to frequency when speed of alternator increases?
So the speed of an alternator is directly proportional to its frequency therefore by increasing the frequency of an alternator its speed will also increase.
How do you change the frequency of an alternator?
Frequency of an alternator is given by f = PN/120 where P is the number of poles and N is the RPM. Since the number of poles are fixed for an alternator the only way to adjust the frequency is by adjusting the speed RPM of the alternator.
What happens during the failure of prime mover in an alternator?
During the failure of prime mover in an alternator which relay is used to restore the working condition Answer.1. Reverse Power Relay If two synchronous generator is running parallel and the total load is divided among two then one generator takes half of the total load of it.
What happens when the excitation of an alternator is constant?
Now if the excitation varies then the output currents vary along with voltage, but the speed is constant and power demand or load on the alternator is also constant. Since Input to prime mover is kept constant, the real power generated remains unchanged (as per the load demand).
What is the reverse power of synchronous alternator?
Then the alternator fails to supply power but starts receiving power from live electric bus. This time the synchronous alternator takes power acts as an synchronous motor and run the engines or turbine in uncontrolled high speed. This is called reverse power.