Lingo...s about Electricity...A320
Joined: Jul 1999
Posts: 352
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From: Europe
Originally Posted by IFixPlanes
... please try to learn the difference between fundamentals and aircraft related data.
west lakes,
The innards of a CSD looks something like this:
Cleverly disguised as a responsible adult
Joined: May 2007
Posts: 1,117
Likes: 0
From: On the western edge of The Moor
Roger oveur - yeah good film
regarding the rpm figures is it fair to say that design depends on materials as I posted, space available etc. I would also (carefully - I know more about electricity than mechanicals & electricity is scary
) suggest that the higher the speed differential being handled by the csd the higher the mechanical effort to operate it on top of the load imposed on the engine by the generators. End of the day engines prime function is to power a/c in flight and keep it there so reducing losses for other uses is preferable.
Loose rivits
the frequency range quoted by Clarence (may I call you that) is =/-1%. this matches most public supply systems.
Tolerances
as in an engine the gap between the rotor and the stator needs to be as small as possible to improve efficiency am sure that as engines developed their rpm increased and the clearance between parts decreased. which is possibly why generator rpms are increasing. also the fewer the coil pairs the lower weight and the smaller the unit - you don' have to fit as much wire in.
As always if the two bits collide - bad.
Another aside
In the late 1950's a power station was commisioning a new 90mVA set. steam added to turbine and run up to speed, connected to grid and throttled up to generate - BANG!
Part of the turbine took flight vertically, throught the roof, over an adjacent building and landed on a shed in an adjacent field.
Cause a 1/2 pint tin mug left in a steam pipe!
regarding the rpm figures is it fair to say that design depends on materials as I posted, space available etc. I would also (carefully - I know more about electricity than mechanicals & electricity is scary
) suggest that the higher the speed differential being handled by the csd the higher the mechanical effort to operate it on top of the load imposed on the engine by the generators. End of the day engines prime function is to power a/c in flight and keep it there so reducing losses for other uses is preferable.Loose rivits
the frequency range quoted by Clarence (may I call you that) is =/-1%. this matches most public supply systems.
Tolerances
as in an engine the gap between the rotor and the stator needs to be as small as possible to improve efficiency am sure that as engines developed their rpm increased and the clearance between parts decreased. which is possibly why generator rpms are increasing. also the fewer the coil pairs the lower weight and the smaller the unit - you don' have to fit as much wire in.
As always if the two bits collide - bad.
Another aside
In the late 1950's a power station was commisioning a new 90mVA set. steam added to turbine and run up to speed, connected to grid and throttled up to generate - BANG!
Part of the turbine took flight vertically, throught the roof, over an adjacent building and landed on a shed in an adjacent field.
Cause a 1/2 pint tin mug left in a steam pipe!
Joined: Sep 2005
Posts: 94
Likes: 8
From: Ontario, Canada
why so fast
In case someone is wandering why 400 Hz and not 50 or 60 Hz as household equipment: probably because by the time they were designing it, the magnetic materials could handle such frequency without excessive losses. The motivation for going faster is that you end up with a smaller & lighter unit to do the same job: convert certain amount of mechanical power to electrical power.
Does anyone know what sort of generator frequencies are used on modern fighter jets where weight is at a premium? I imagine that such designs start with a clean sheet, without any need for legacy compatibilities. Or am I dellusional?
BM
Does anyone know what sort of generator frequencies are used on modern fighter jets where weight is at a premium? I imagine that such designs start with a clean sheet, without any need for legacy compatibilities. Or am I dellusional?
BM
Joined: Mar 2006
Posts: 1,974
Likes: 0
From: Choroni, sometimes
@balsa model
Don't know about fighters, but about A 380 which has great concerns about weight....
It has a free (variable) AC power generation which requires no CSD/IDG.
Frequency is 380 Hz - 800 Hz.
It has a free (variable) AC power generation which requires no CSD/IDG.
Frequency is 380 Hz - 800 Hz.
Joined: Sep 2005
Posts: 94
Likes: 8
From: Ontario, Canada
380 AC bus frequency
Interesting..
Slower than I expected but it makes sense that they relaxed frequency tolerance. Nowadays, designing small and light rectifiers that can take a wide frequency range is easy. Input transformers can be altogether dispensed with.
And now that I think of it again, maybe fighter jets don't bother with AC bus at all.
Slower than I expected but it makes sense that they relaxed frequency tolerance. Nowadays, designing small and light rectifiers that can take a wide frequency range is easy. Input transformers can be altogether dispensed with.
And now that I think of it again, maybe fighter jets don't bother with AC bus at all.
