400 Hz

[mull982]

I believe the whole 400Hz thing can be represented by the equation for flux in a motor:

flux = (Vm / w*N) cos wt

where Vm = source voltage
w = frequency
N = number of winding turns

As you can see from the equation, by increasing the frequency you can thus decrease the number of winding turns and still keep the same flux density. It is this decreased numver of winding turns that allows the motor or equipment to me smaller and lighter. Keeping the same flux density allows the motor to provide the same torque and hp.

This is just my understanding of it from a theoretical point of view.

 

[Pierre C Belarge]

Of course on a plane or a sub the circuit length has some inherent limitations. :smile:

What about the length of the earth ground?:grin:

 

[ohmhead]

400 hertz keeps you in the air better

400 hertz keeps you in the air better

Well just a little added facts from a navy book on 400 hertz power .

Aircraft at 400 hz at 115 volts this is to solve ripple sub harmomic frequencies in the range of 1 -20 hz and those freqs which produce a beat freq in this range with harmonics .

400hz is in the range of maximum aircraft control system response meaning line freq modulation to power supply line frequency .

frequency can change with a minute varible rate change meaning its undesirable to have this with avionics and control functions of aircraft auto pilot and instrumentation navigation stuff AIRCRAFT CONTROL SIGNALS .

meaning control and response to complex onboard aircraft flight stuff meaning rate signals to autopilot , servos or noiseless indicators and instruments attiude related signals pitch yaw and roll electronics .

So 400 hertz can solve these issues onboard meaning that gyroscope power when you at 35000feet you just feel better knowing its got a 400 cycle pure dc voltage and constant nosieless free current supply and line to load freq is at its best signal or your day will be a bad day !!! take care just out of a old navy electricians book .

 

[LarryFine]

. . . you just feel better knowing its got a 400 cycle pure dc voltage . . .

400 Hz DC? (I know what you meant, but . . . )

 

[ohmhead]

400 Hz DC? (I know what you meant, but . . . )

Well gyroscope circuit inertial navigation = ac power not 400 volts but 34volts ac power next band pass filter one , next band pass filter two , which is your reference signal next demodulation circuit next voltage compensator circuit next dc pulse width converter circuit ect ect ect ect ? most gyro electronics is dc the generators on aircraft are not just 400 cycles at 115 volts there is multiple voltages on different winding outputs of generator . most have multi taps on output . best to yas does this help ?

 

[glene77is]

400 Hz DC?

Larry,

Come on now! YOU know what he means.
Adding the "DC" is like adding "!!!" to the information.

Navy guys are like that.
(My Dad kicked sharks in the Pacific for nine hours, in '42,
and he always added extra words to his description of that. :grin

 

[ohmhead]

Larry,

Come on now! YOU know what he means.
Adding the "DC" is like adding "!!!" to the information.

Navy guys are like that.
(My Dad kicked sharks in the Pacific for nine hours, in '42,
and he always added extra words to his description of that. :grin

Well i guess to add more info to what i said in the last post thats so confusing to what or how we said it .

The power supply is the key a 400 cycle ac wave is easy to produce a dc current from and more effective to get pure dc current and filter out harmonics and trash . thats about as simple as it gets . best to yas