|SYNCHRONOUS SPEED FORMULA FOR ELECTRICAL MACHINES|
Saturday, September 17, 2011
ELECTRICAL ENGINEERING QUESTIONS PART2
Hi itzme !!!.Please mention your name and also post your comments in latest post so that visitors can get a notice of the questions.Thanks for reading my blog and asking more questions.Hope my answers are useful to you.Next Electrical Engineering Question is "What is the use of Synchronous Generator?Which is more preferred synchronous/asynchronous alternators ?"
As the name indicates Synchronous generator runs at the synchronous speed.The relation for synchronous speed is given by,
Keeping the frequency of ouput voltage of the alternator as fixed, the synchronous speed changes based on the number of poles of the machine.For example,Our supply is 50 Hz.so for a 4 pole machine Ns would be 1500 rpm but for a 6 pole machine Ns would be 1000 rpm.
The synchronous alternator generates the output voltage at a constant frequency as the machine is made to run at synchronous speed.All the electrical appliances in our country are rated for 50 Hz,so the supply provided by electric board should be 50 Hz supply.Therefore synchronous alternators are more preferred than the asyncronous alternators.
In USA they use 60 Hz supply,so the machine's number of poles and synchronous speed will vary according to their frequency.