E
Estimation
- Jan 1, 1970
- 0
Why do aircraft run on 400 Hz in stead of 60Hz?
Paul
Electrical Estimator
Paul
Electrical Estimator
Why do aircraft run on 400 Hz in stead of 60Hz?
Correct. I can pick up a 100 kVA 400 Hz generator with one hand.
Question: What weights nothing but, when loaded onboard an airplane, can
keep it from taking off?
Doesn't an injunction carry the full weight of law?
B J Conner said:The synchronous speed of a 400 hrz motor is 24,000 RPM. That will make a
good gyrocompass.
daestrom said:Not *all* 400 hz machines are that fast. RPM = F*120/ (Poles). So a 26
pole 400 HZ motor has a sync speed of only about 1846 RPM
We had some M-G sets for 400hz that were this many poles, driven by DC
motors.
daestrom
art said:What was the application for them?
Art.
make
art said:I red that military some where ordered 4000A DC service, you explain one of
the possible application. But why DC driven?
Magetic cores (in transformers, motors, generators) can be ~1/7 of the
weight. Weight is really important on airplanes.
daestrom said:The particular application (submarine) already had a large, DC source. The
DC busses are more reliable than even the 'vital' AC busses. And
variable-speed DC drive motor is pretty simple (i.e. robust) technology in
their day.
400HZ was also used in basic navigation equipment (like gyrocompass). The
starboard DC bus that powered emergency propulsion, had DC diesel tie-in,
battery-bus tie, 400HZ MG and emergency steering&diving hydraulics was
called the 'go home' bus. As electrical operator, if I kept *that* one on,
I knew, "well, at least we can go home."
I'm sure there are other applications that would prefer 60HZ -> 400HZ M-G
sets instead. My brother (civilian) recounts story of large 400 HZ/12V m-g
(60 -> 400) that was used for computer room power supply. Something about
rectified 400HZ was smoother to filter before such wide spread use of
switching power supplies. (these are *old* computer rooms that are long
gone now ;-)
daestrom
s said:I thought one reason for 400-415Hz on mainframes was to get high platter
speeds using 3ø induction motors?
--s falke