making electricity at the generating station
- Thread starter DIYedboy
- Start date
Electromagnets being spun within large coils.
The Electromagnets being energised from auxiliary generators on the same shaft.
The Electromagnets being energised from auxiliary generators on the same shaft.
Lots of info on Wikipedia
I don't know for sure.
But my guess is that you wouldn't find a permanent magnet in a modern power station generator. Even the alternator in a modern car uses a field winding, and needs some battery power before it will start to produce electricity.
Have you tried searching. I'm not going to google "self-excitation", but I found this with a different search: http://en.wikipedia.org/wiki/Electrical_generator#Excitation
But my guess is that you wouldn't find a permanent magnet in a modern power station generator. Even the alternator in a modern car uses a field winding, and needs some battery power before it will start to produce electricity.
Have you tried searching. I'm not going to google "self-excitation", but I found this with a different search: http://en.wikipedia.org/wiki/Electrical_generator#Excitation
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Well it's not all what it seems starting furthest from turbine there is a unit with a wound core but there is no current or voltage on that winding during running conditions it is used to make the permanent magnet rotor into a magnet as one could not assemble it if already magnetised two rods are screwed in it requires around 100A for 5 seconds to magnetize it then rods removed.
However this only supplies the oil pump with power and has nothing to do with main generator.
There are a whole series of brushes and slip rings on the rotor but in fact these are only to monitor with the generator is classed as brush less.
So the AVR supplies the second stator which in turn gives power to the second rotor which then supplies this power through rotating diodes to the third rotor which causes the third stator to be energised. Memory little hazy think output was 11,000 volts.
I worked on two 750MW units and four 600MW units the description is of the latter as was not as involved with former units. The rotors are cooled by having hollow windings through which is passed hydrogen gas think stator is water cooled but not sure.
The hydrogen gas is keep from leaking with oil and since it's used to seal it's called seal oil remember green peace raiding one of the power stations due to the use of seal oil some one thought it came from seals.
First large power station I worked on had 12 diesel engine driven generators dotted around the power station of 1.5MW each as well as the main pair of 750MW generators these were to ensure should there be a major grid problem the water pumps would still run so the reactor would not over heat.
I remember the news on the building announcing the power station had produced first power put into the grid it was these 12 diesel generators not the main ones which had been tested the reactor was still not powered up.
At the time of building these power stations I was just an electrician working for GEC Large Steam Turbines and not an electrical engineer but for that firm there were only 6 electricians so we got quite involved although on the site there would have been 100's of electricians they worked for different firms.
On the Falklands Ruston diesels were also used nearly the same as those used for stand-by to power the whole Island again from memory all 1.5MW but I am uncertain if I would be breaking the law to give more details. About half the number that were used as stand-by.
My father was also technical supervised for a private set of power stations the largest was around the 15MW output of electricity however it also supplied steam, blast furnace gas, coke oven gas, and air to rest of works so was a true power station. It was multi-fuel coal, coke, both gases and oil fired using just steam turbines.
However the last one I worked on had two turbines on the same shaft first was a gas turbine second was steam generated from waist heat from gas.
Have worked on gas turbines both at a gas terminal and on an oil drilling ship well call it a ship but only had bow thrusters driven from those gas turbines to hold it in position it was towed by tugs to site.
From memory all these were classed as brush less generators i.e. all had rotating diodes.
However this only supplies the oil pump with power and has nothing to do with main generator.
There are a whole series of brushes and slip rings on the rotor but in fact these are only to monitor with the generator is classed as brush less.
So the AVR supplies the second stator which in turn gives power to the second rotor which then supplies this power through rotating diodes to the third rotor which causes the third stator to be energised. Memory little hazy think output was 11,000 volts.
I worked on two 750MW units and four 600MW units the description is of the latter as was not as involved with former units. The rotors are cooled by having hollow windings through which is passed hydrogen gas think stator is water cooled but not sure.
The hydrogen gas is keep from leaking with oil and since it's used to seal it's called seal oil remember green peace raiding one of the power stations due to the use of seal oil some one thought it came from seals.
First large power station I worked on had 12 diesel engine driven generators dotted around the power station of 1.5MW each as well as the main pair of 750MW generators these were to ensure should there be a major grid problem the water pumps would still run so the reactor would not over heat.
I remember the news on the building announcing the power station had produced first power put into the grid it was these 12 diesel generators not the main ones which had been tested the reactor was still not powered up.
At the time of building these power stations I was just an electrician working for GEC Large Steam Turbines and not an electrical engineer but for that firm there were only 6 electricians so we got quite involved although on the site there would have been 100's of electricians they worked for different firms.
On the Falklands Ruston diesels were also used nearly the same as those used for stand-by to power the whole Island again from memory all 1.5MW but I am uncertain if I would be breaking the law to give more details. About half the number that were used as stand-by.
My father was also technical supervised for a private set of power stations the largest was around the 15MW output of electricity however it also supplied steam, blast furnace gas, coke oven gas, and air to rest of works so was a true power station. It was multi-fuel coal, coke, both gases and oil fired using just steam turbines.
However the last one I worked on had two turbines on the same shaft first was a gas turbine second was steam generated from waist heat from gas.
Have worked on gas turbines both at a gas terminal and on an oil drilling ship well call it a ship but only had bow thrusters driven from those gas turbines to hold it in position it was towed by tugs to site.
From memory all these were classed as brush less generators i.e. all had rotating diodes.
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As a PS http://en.wikipedia.org/wiki/Alternator#Brushless_alternators does give the idea but on smaller alternators as used with cars, plant and trucks the brush less generator is not that common. Paris Rhone (not sure of spelling) had an odd system with the coil being held on a web and the soft iron core spinning either side of it. Delco Remy also had a odd system the coil being held from one end and the soft iron core again spinning over it they did not have rotating diodes, but were brush less.
With motor vehicle the brush less design was to reduce maintenance and for there size the output was low.
With small marine engines the use of inverter generators has taken off. The idea is that the engine revs can vary but output cycles remain static so the AC is turned to DC then back to AC.
Smaller portable generators also use the same idea but for a different reason it allowed the engine speed to increase with load giving a low fuel consumption when drawing little current. There is also the type with a simple current operated solenoid which also ticks over at no load but frequency of output also drops.
Larger generators use a complex system to decide how much of the load to share but smaller generators say 250kVA often use droop to load share. If a set of generators will reduce speed by 5% from full load to no load then this can be used to get a series of generators to share the load. I have used 12 x 600kVA generators like this but from my experience I would think about 25 generators would be the limit. Using this method often the frequency was slightly out so we had a quartz and frequency regulated clock so we could keep all other clocks on site somewhere near correct.
With motor vehicle the brush less design was to reduce maintenance and for there size the output was low.
With small marine engines the use of inverter generators has taken off. The idea is that the engine revs can vary but output cycles remain static so the AC is turned to DC then back to AC.
Smaller portable generators also use the same idea but for a different reason it allowed the engine speed to increase with load giving a low fuel consumption when drawing little current. There is also the type with a simple current operated solenoid which also ticks over at no load but frequency of output also drops.
Larger generators use a complex system to decide how much of the load to share but smaller generators say 250kVA often use droop to load share. If a set of generators will reduce speed by 5% from full load to no load then this can be used to get a series of generators to share the load. I have used 12 x 600kVA generators like this but from my experience I would think about 25 generators would be the limit. Using this method often the frequency was slightly out so we had a quartz and frequency regulated clock so we could keep all other clocks on site somewhere near correct.
Don't believe that utter tosh.
What they are is massive rats in big wheels, they run around making electrikery so that they can then get fed.
All of the above is rubbish. This informative video tells the truth, including the fact that there has been no new electricity generated since 1937.
Believe, and ask for a refund of your energy bill!
https://www.youtube.com/watch?v=pruCd9qcKSQ
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Special tree rats are used called squirrels in some generators but in the main they are used with motors google squirrel cage motor to learn more.Don't believe that utter tosh.
What they are is massive rats in big wheels, they run around making electrikery so that they can then get fed.
The generator on the back of the main unit used to drive the lucubration oil pump is the largest permanent magnet generator I have seen. However the problem is it has a fixed output which is all well and good driving a single motor but not much good when the load varies.
As to smaller versions with wind chargers the problem is you can use so much power energising the field when wind is not blowing that on average it uses as much as is generates so these do use permanent magnets. This means excess power has to be turned to heat by the regulator.
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