400 Hz

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haskindm

Senior Member
Location
Maryland
I have a contractor friend that has been asked to install a 400-hz generator and wiring on a military installation. He has received two conflicting instructions:
1. Use a 120/240 volt snap-in type breaker panel.
2. Use only a 120/240 volt bolt-in type breaker panel.
My questions are: Are there panels labelled and listed for 400-hz installations? Which type of panel would be better for this installation and why?
Thanks for any help that you may provide.
 

charlie

Senior Member
Location
Indianapolis
Re: 400 Hz

We just had this discussion and your question is already answered here. If you do not agree, please go ahead and post a follow up question. :D
 

sagman

Member
Re: 400 Hz

This may sound like a silly question, but what is the purpose of having a system operate at 400 Hz?

"Curiosity killed the Cat"

Steve
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
Re: 400 Hz

It is a common power source for certain electronic equipment, such as airport radar systems and aircraft on-board systems. I am not certain of its advantages, but I would suppose that it provides a more precise control of information flow. You can get more "pings" out there and back if the power source has more frequent ups and downs. If you want something more near to the truth, you'll have to hope there are electronics experts on this Forum.
 

peter d

Senior Member
Location
New England
Re: 400 Hz

I read somewhere (I forgot where :( ) that 400 Hz is common in aviation, particularly airplanes, so that motors can be much smaller and lighter while still being very powerful.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
Re: 400 Hz

For aircraft, at 400 Hz, motors and transformers and inductors are all smaller and lighter. So are capacitors. Also, 400 Hz is easier to filter to get DC.

Steve
 

physis

Senior Member
Re: 400 Hz

Charlie B., I don't remember radars being dependent on the supply frequency. But it's been a while, I never actually built or worked on those, and I don't have the books for that any more.
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
Re: 400 Hz

Originally posted by steve66: For aircraft, at 400 Hz, motors and transformers and inductors are all smaller and lighter. So are capacitors. Also, 400 Hz is easier to filter to get DC.
Good answer. Wouldn't have thought of that myself. One "attaboy" to steve66! :)
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
Re: 400 Hz

Thanks. It's not often I get an "attaboy". And we all know that a single "whoops" can wipe out about a dozen "attaboy's" :D

I actually have a FCC License that allows me to work on radio's and radar for aircraft and ocean going vessels. Not a lot of use for that here in Central Illinois though :D

Steve
 

dereckbc

Moderator
Staff member
Location
Plano, TX
Re: 400 Hz

It is true 400 hz uses much lighter transformers, inductors, and generators. The con side of the equation is higher voltage drops.. Hence the reason for switch mode power supplies. You rectify the line AC directly to DC (without any step-up/step-down transformer, invert the DC back to high frequency AC (>10KHz), then go through a step-down transformer (1/5th the size of its 60Hz counter part) and rectify again back to desired DC voltage.
 

foxch47

New member
Re: 400 Hz

An area I'm familiar with, being a CH-47 test pilot. As noted above, this is a weight/size issue. The Chinook has two 80 KVA oil cooled 3 phase generators weighing 48 pounds a piece, as well as a 20 KVA air cooled 3 phase auxiliary generator. Two 200 AMP rectifiers weighing 24 pounds provide DC power. The helicopter max weight is 50,000 lbs, with an empty weight of 24,000 pounds. On long trips, a standard coffee pot perks a quick cup of coffee (under 2 minutes for 12 cups) using that 400 Hz.
 

rattus

Senior Member
Re: 400 Hz

fox, I would expect a coffee pot to work the same from DC up to a few KHz. And too, water boils at a lower temperature at higher altitudes.

[ April 22, 2005, 12:48 PM: Message edited by: rattus ]
 
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