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04-14-2012, 10:10 PM
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#1
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Senior Member
Join Date: Dec 2011
Location: NY
Posts: 292
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Have you heard of this
Im bidding a job where two panels are fed from a combination converter to fed a 28V DC panel, and a 120/208V 400HZ panel.
Both panels are protecting just receptacle branch circuits located in a ECM Shop at an Air Base but I have never seen this before
So before I go for the site walk thru, can anyone give me any tips as to why they need these receptacles??? Just so I don't look like a total fool.
What do you guys think they are plugging in?
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04-14-2012, 10:13 PM
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#2
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1,000,000th Poster
Join Date: May 2010
Location: Portland
Posts: 9,474
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Aircraft equipment runs on 400Hz because the higher frequency lets you run smaller motors and transformers, which reduces unnecessary weight on the planes.
The 28V, I have no clue.
-John
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The Following User Says Thank You to Big John For This Useful Post:
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04-14-2012, 10:29 PM
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#3
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This amp goes to 11
Join Date: Nov 2011
Location: New Hampshire
Posts: 643
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Quote:
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Originally Posted by Big John
Aircraft equipment runs on 400Hz because the higher frequency lets you run smaller motors and transformers, which reduces unnecessary weight on the planes.
The 28V, I have no clue.
-John
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I've done some 400hz work before. BAE systems has a bunch of panels that are 400hz and they design aircraft electrical systems. Makes sense now!!
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04-14-2012, 10:31 PM
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#4
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Electricity is Amazing!
Join Date: Jan 2012
Location: Cornfield, NE
Posts: 826
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Get your Wiggy out
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04-14-2012, 10:31 PM
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#5
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This amp goes to 11
Join Date: Nov 2011
Location: New Hampshire
Posts: 643
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Quote:
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Originally Posted by Big John
Aircraft equipment runs on 400Hz because the higher frequency lets you run smaller motors and transformers, which reduces unnecessary weight on the planes.
The 28V, I have no clue.
-John
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I've been flying for years and all of a sudden I start thinking about gyros. They're used for all kinds of instrumentation it aircraft.
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04-14-2012, 10:35 PM
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#6
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Senior Member
Join Date: Sep 2011
Location: Mississippi
Posts: 767
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Quote:
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Originally Posted by Big John
Aircraft equipment runs on 400Hz because the higher frequency lets you run smaller motors and transformers, which reduces unnecessary weight on the planes.
The 28V, I have no clue.
-John
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Been on Corps of Engineer powerhouse jobs that their instrumentation was fed via 28VDC precision power supplies, John. Maybe that could be the case here?
- Jim
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04-14-2012, 10:39 PM
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#7
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This amp goes to 11
Join Date: Nov 2011
Location: New Hampshire
Posts: 643
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Yeh thats gotta be like a avionics lab of some sort. Remember input frequency is output frequency. Thats totally avionics or I'm Capt'n Kirk!!
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04-14-2012, 10:42 PM
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#8
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1,000,000th Poster
Join Date: May 2010
Location: Portland
Posts: 9,474
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Quote:
Originally Posted by thoenew
Get your Wiggy out
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I think someone once posted a picture on here of a sign in one of these places that actually forbade the use of Wiggys because the coils are only designed for 60Hz, and won't respond at all to 400Hz. You'd think a bus was dead and instead it would light you up. 
EDIT: Found it.
-John
Last edited by Big John; 04-14-2012 at 10:46 PM.
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04-14-2012, 10:43 PM
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#9
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This amp goes to 11
Join Date: Nov 2011
Location: New Hampshire
Posts: 643
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Gyros in aircraft have to "spin up" to a certain frequency to simulate gravity and your pain old 12-24-48VDC doesn't work for some reason. I've been flying for years and after you shut the engine down you can still hear the gyros winding down for about 2 mins after. Avionics definitely IMO.
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04-14-2012, 10:44 PM
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#10
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This amp goes to 11
Join Date: Nov 2011
Location: New Hampshire
Posts: 643
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Quote:
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Originally Posted by Big John
I think someone once posted a picture on here of a sign in one of these places that actually forbade the use of Wiggys because the coils are only designed for 60Hz, and won't respond at all to 400 cycles. You'd think a bus was dead and instead it would light you up.
-John |
I wanna try!!
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04-14-2012, 10:44 PM
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#11
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Wire Ninja
Join Date: Jan 2007
Location: Beautiful Cumberland Valley, in PA
Posts: 16,794
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Aircraft ground power units supply 120 at 400hz and 28vdc. This sounds like a permanent install of a GPU.
__________________
One reason not to give DIY advice:
Catch a man a fish and you can sell it to him.
Teach a man to fish and you’ve ruined a good business opportunity.
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04-14-2012, 10:55 PM
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#12
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This amp goes to 11
Join Date: Nov 2011
Location: New Hampshire
Posts: 643
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Quote:
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Originally Posted by MDShunk
Aircraft ground power units supply 120 at 400hz and 28vdc. This sounds like a permanent install of a GPU.
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I've noticed your a pretty smart guy thats done alot of different stuff. Kinda reminds me of me! Not to mention your on ET this time of night on a Saturday!! All me mates have fallen asleep around the fire and I'm thinking of opening my new beauty salon with a sharpie  never fall asleep in public has always been my motto.
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04-14-2012, 11:29 PM
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#13
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This amp goes to 11
Join Date: Nov 2011
Location: New Hampshire
Posts: 643
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Think about this your average run of the mill microwave runs at like 2500Mz.....not so weird anymore is it?
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04-15-2012, 12:27 AM
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#14
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Senior Member
Join Date: Jan 2007
Location: Not from GA as long as Cletis is there!
Posts: 1,847
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Quote:
Originally Posted by TimChaput69
I've noticed your a pretty smart guy thats done alot of different stuff. Kinda reminds me of me! Not to mention your on ET this time of night on a Saturday!! All me mates have fallen asleep around the fire and I'm thinking of opening my new beauty salon with a sharpie never fall asleep in public has always been my motto. |
It will be allowed only if you let us critique the art work. 
__________________
Water and women are in short supply! There's not enough dope for us all to get high! Jimmy Buffett!
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04-15-2012, 12:50 AM
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#15
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This amp goes to 11
Join Date: Nov 2011
Location: New Hampshire
Posts: 643
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Quote:
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Originally Posted by jbfan
It will be allowed only if you let us critique the art work. |
If I could figure out how to post a pic from my phone there would be some really priceless photos here tonight!! I just put fake sharpie eyelashes on my friend Max, next is Ritchie......I'm thinking a "I was born a lesbian" tattoo on his forarm. The last friend has a shaved head so I'm thinking a third eye, right in the middle of his forehead! What do you guys think? I've got probably an hour before anyone of them stir.
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04-15-2012, 12:56 AM
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#16
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Senile Member
Join Date: Jan 2007
Location: Honolulu
Posts: 7,394
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At honolulu international, they paint any conduit and panels with the 400 mandarin orange so most dummies know what they are about to get fried with.
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The Following User Says Thank You to macmikeman For This Useful Post:
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04-15-2012, 02:11 AM
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#17
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Modérateur
Join Date: Mar 2007
Location: NE Wi / Paris France{ In France for while }
Posts: 4,232
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Quote:
Originally Posted by Big John
Aircraft equipment runs on 400Hz because the higher frequency lets you run smaller motors and transformers, which reduces unnecessary weight on the planes.
The 28V, I have no clue.
-John
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The 400 HZ is used on motours and transfomers and few electrique loads ( also with Air Cond unit ) but for 28 Volts DC that is a battery bus voltage that used for few instrurment on the IP ( instrusment panel ) plus few lights that do run off from 28V source.
( I do know navation and landing lights are on 28 V source )
Oh yeah from time to time if you have good 28V battery it can light up the turbine up without much effort.
Merci,
Marc
__________________
Bleu est beau.
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04-15-2012, 11:13 AM
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#18
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Coffee drinking member
Join Date: Sep 2010
Location: IL
Posts: 6,041
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Quote:
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Originally Posted by TimChaput69
I wanna try!!
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Please have someone take a pic as you try it.
We love pictures.
:-)
__________________
Teacher, my brain is full... Can I go home now?
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04-16-2012, 05:57 AM
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#19
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Crazy about lights
Join Date: Jun 2010
Location: Cairns Australia
Posts: 614
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I beleive aircraft use a 24v battery system,
So the 28v could be for charging aircraft batteries,
Or even powering some auxilary systems.
28v is about right for charging a 24v battery !
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