aircraft power supply 400 Hz and beyond? 1

[Sirius]

Dear All,

up to now the simple picture I had about power supply was:

60 Hz /115 V is used in the USA for instance

50 Hz / 230 V is used in Europe for instance

and 400 Hz / 115 V is used in aircrafts for various reasons which are already discussed in this forum.

Now recently I learned about a requirement for some aircraft equipment that it should be able to cope with
supplied power which can vary from let say 400 Hz to 600 Hz for instance. I'm not sure whether I understood it well, but for me it seemed that this frequency variation could occur during take off and landing.

Now my questions:

is such a frequency range requirement for power supply quite common for aircraft equipment?

What could be the reason for such a frequency range requirement on aircraft level?

Best Regards
Sirius

 

[IRstuff]

MIL-STD-704E Figure 7 shows a maximum of 480 Hz as overfrequency.

TTFN

 

[jcai]

GOOD MORNING FOLKS -
AS YOU SAY THE NORM IS 400 HZ AT 208V./ 115V. ON LARGER AIRCRAFT - SMALLER ONES USE 28.5V. D.C.
SOME OF THE LATER MILITARY AIRPLANES USE 270V. D.C. - AS DOES THE SPACE STATION ETC.
THE LATER THINKING IS TO GO TO FREQUENCY WILD / VOLTAGE WILD ALTERNATORS AS IT DOES NOT REQUIRE A C.S.D.
THE A.380 IS GOING THAT WAY AS WELL AS RAPIDLY BECOMING AN ALL ELECTRIC AIRPLANE RATHER THAN LARGELY HYDRAULIC OR PNEUMATIC .

SEEYA J.C.

 

[IRstuff]

Actually, MIL-STD-704E compliant DC supply is 28.0 VDC with a range from 22 to 29 V, see TABLE II in the spec.

As for 270 VDC, not sure what you mean by "later" military airplanes, since MIL-STD-704D-1980 has specifications for 270 V supplies.

Additionally, 270 V is normally a derived supply, in that there is no direct generator of 270 V, it comes from filtered, full-wave rectified, 3-phase 400Hz AC power.



TTFN

 

[aviat]

The Bombardier Global Express came out with variable frequency generators (VFG)in 1999. It is a TRW Lucas system. It is different from frequency wild which has been out for several years. With VFG, some components such as fuel pumps,actually change speed with changes in engine speed. Since that time other biz jets and turboprops have come out with VFG's.

http://www.janes.com/micro_sites/paris/aircraftdata/bombardier_globalexpress_02.shtml