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#122767 02/03/06 07:05 PM
Joined: Jun 2004
Posts: 202
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Years ago, I worked in a building on a RAAF base that had 415/240VAC 50 Hz, 115VAC 50Hz, 208/115 60Hz & 208/115VAC 400Hz (the 60 & 400 Hz came through supplied through rotary convertors). These were all disconnected in the early 1990s & only the 415/240VAC 50 Hz & 115VAC 50 Hz remains now (fed from a pair of rather large transformers under the floor-about 100 Kva each)

#122768 02/03/06 07:48 PM
Joined: Jun 2001
Posts: 642
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When I was in the USAF as a ground support equipment technician, I worked on a lot of motor generators that are single shaft 60Hz motors to 400 Hz generators. Many of these motor generators were older than I was at the time. Some of these were called the MD-1 or -2 or -4. They ranged in size from 15 KW to 75 KW. When I was stationed At RAAF Lakenheath in the U.K. we changed over to 50Hz to 400HZ equipment from the older 50 to 60 Hz then 60 to 400HZ units. One piece instead of two is easier to maintain and works better.
400HZ power is standard on aircraft almost every where in the free world. some of the reasons are above.


ed
#122769 02/08/06 04:46 AM
Joined: May 2003
Posts: 2,876
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e57 Offline
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400Hz is also used for radar and com. gear. (Aviation and Military) From what I understand, it offers a much smoother wave form when rectified for those uses with a higher available current. (as the alternation spends a lot less time at lower potentials)

FYI 50 and 60 will give you a kick in the pants, 400 will burn you in the proccess.

As for generator shaft speeds, they run roughly about the same general speed as 50/60 gennie sets, they just have more magnetic fields on the stator so the armature crosses more fields per RPM. Or at least the sets I have worked with... I assume a convertor (I haven't used any) would operate just like a rotory phase convertor, instead of just adding a phase, add a bunch more fields to cross.


Mark Heller
"Well - I oughta....." -Jackie Gleason
#122770 03/02/07 02:29 AM
Joined: Mar 2007
Posts: 404
Member
Sorry for dragging up a year-old topic, but we (I work for a subcontractor of American Airlines at PDX) use a solid-state electronic converter, manufactured by FMC technologies. It converts standard 480V 60Hz to 3-phase 110/208V at 400Hz via a 6-wire connector. Most of the systems on the aircraft run on the 400Hz AC, but there are a few things (like lighting) that run on 28VDC. I'm not entirely sure what the sixth conductor on the plug is for, but I supsect it's probably a second ground.

Here is the converter: http://www.fmctechnologies.com/AirportEquipmentServices/GroundSupportEquipment/GroundPower.aspx

Here is the connector: http://www.usairmotivegse.com/imagenes/producto/3989R676XXE7198.jpg

There are other manufacturers for this equipment as well.

#122771 03/02/07 07:20 AM
Joined: Dec 2001
Posts: 2,498
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Member
I was just told that many European industrial locations (mostly metal work) use 200 Hz and 300 Hz for hand tools like angle grinders! That's for two reasons, at that frequency they can use lightweight 3ph asynchronous motors that are basically indestructible, and the synchronous speed is much higher.
I saw that used in a smallish company that makes turbines for small hydro plants. All tools use green 3+Earth CEE connectors, the most common system is 265V 200 Hz.

#122772 03/02/07 05:52 PM
Joined: Sep 2005
Posts: 97
J
Member
We are a steel engineering company and we have 300Hz 3 phase distribution for grinders. The reason we use them is that they dont slow down when you apply pressure. Sturdy - maybe they are often away for repair. Effective - extremely. I recall that they are 200V and are Bosch but I cant find any info on the internet about them. We are upgrading the system in a few weeks to MCB and RCD setup for personnel protection.

I will get some pictures on Monday of the system.


I took my time, I hurried up, The choice was mine, I didn't think enough
#122773 03/03/07 02:51 AM
Joined: Dec 2006
Posts: 16
S
Junior Member
400hz comes from 2 onboard MG Sets and it is used for Synchros and Servos. The 400hz gives greater accuracy transmitting that kind of angular signal. If you want to know more check out the NEETS Navy Electricity and Electronics Training Series. I was a navy ET and we used the 400hz for radar and communication antennas. The folks who really knew it inside and out were the IC Men (Interior Communications) and there are quite a few in our trade.

#122774 03/03/07 11:01 AM
Joined: Sep 2006
Posts: 58
Y
Member
I was a gun fire control tech. in the Navy. Our weapons radar equipment was fed from two 400 hz mg sets. It was 40 years ago so I'm not sure about the snchro-servo system we used, but I believe they were 120/60. I still beieve that us FT's had the best job on the ship.

#122775 03/03/07 06:48 PM
Joined: Mar 2005
Posts: 1,213
S
Member
Hey, those cables are the shore power cables I was asking about in the NEC forum a few days ago; they're still very much in use! We use those cables for temporary power connections in shore facilities, too.

Due to increasing reliant on COTS gear, 400Hz equipment on ships is getting rarer and rarer. There is still quite a bit of 400Hz gear, though, but most of it now is simple economics: rather than develop 1 component for aircraft and another for ships, it's easier to provide 400Hz power on the ship and keep commonality.

Navy is migrating from MG sets to solid state frequency converters onboard ships, but I'm not aware of any plans to rip out the old MG sets quite yet- there are cost savings in reduced maintenance for new installs, but not enough to warrant outright replacement. Savings in space, weight and moment are also important, and a place where the solid-state units shine. There is one bonus to the old MG sets- they act as rotary UPS, too, and can ride out short power hits.


[This message has been edited by SteveFehr (edited 03-03-2007).]

#122776 03/06/07 10:31 AM
Joined: Aug 2001
Posts: 7,520
P
Member
From johno12345:

Quote

Heat Treatment MG set
This is thought to be the newer motor generator set and runs at 297Hz, I think it might be in need of a wipe over - it is actually royal blue.

[Linked Image]

Close-up:
[Linked Image]


High Cycle Grinder
The sole reason we have these sets. These grinders are quite old and I am led to believe that they don't slow down when pressure is applied making them excellent for grinding metal for a Brinell test.

[Linked Image]


High Cycle Socket & Plug
Socket and plug on the High frequency network. These are standard Lewden sockets and care has to be taken not to plug a welder into these sockets as they are the same.

[Linked Image]

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