B747 Hangar Equipments 3

[alanElec]

Dear air engineers I urgently need some clarifications about two ground support aircarft equipments namely

1.400 Hz Static Generator(AXA 2200 SERIES,180 KVA,TWO OUTPUTS EACH RATED 90 KVA)
2.28 V DC unit

I have a drawing that shows the 400 hz gen in the electrical room and a 200/115 v DB in the hangar.(1)I assume that the output of 400 hz gen is connected to this particular DB,is it? No other fixed output point is shown in hangar.

(2)So that means a flexible 400 hz rated cable is used to supply from the db to aircraft(B747) plugs.?

Last of all where does the 28 V dc unit fit in. We are planing to consider a movable unit.
(3)Where is the output of 28 v dc unit connected?(4)Is it connected to the 400 hz gen by any means or directly to another plug of the aircraft?

http://www.eng-tips.com/threadminder.cfm?pid=2

 

[hokie66]

Why don't you ask the author of the drawing?

 

[alanElec]

I had the same question,but it seems my superior does not want to ask the client the details.

 

[MintJulep]

Clearly that drawing was never intended to show the level of detail you are looking for.

Who do you think might have the details you need, the owner of the drawing, or random strangers on the internet?

 

[alanElec]

I was asking the general arrangement and connection of these equipments. Attaching the drawing was a mistake. Also please not the fact that this is not a student posting but a clarification I needed to move on at work.
All I needed to know was how the ground power equipments were connected to aircraft normally.

1)directly from gpu?
2)from gpu to a DB and then to the flight plug?
3)And how is the 28 v dc connected?

I am not an aircraft engineer,I'm an electrical engineer and this query arised for a job involving refurbishment(mech,elect,plumbing) works for a B747 hangar.The works included supply and installation of Gpu and 28 v dc unit also,of which i have not much idea.

 

[hokie66]

You need to make a site visit to the hangar, pick the brains of the maintenance people on the ground, and also talk to the electrical engineer responsible for the design. Your superior may not to reveal his/your ignorance, but making assumptions or relying on answers from anonymous sources is not likely to have a happy outcome.

 

[alanElec]

Damn right..

 

[PHovnanian]

Alansam, you are going to need more than the attached drawing to figure out the scope of work involved here. I couldn't make out some of the text in the JPG, but it appears that some existing equipment stays and some is to be replaced.

The details of the required connections should be in a one line diagram and there should be some cable specifications. Generally, the cable used for 400 Hz systems is the same as that for 60 Hz systems except for the flexible cord and plug assemblies that connect to the aircraft. Wire is wire and conduit is conduit, so labor rates will be similar to 60 Hz installations. In some cases, 60 Hz circuit breakers and fuses can be used with appropriate re-rating provided by the manufacturer. In other cases, no. So you will have to figure out what has been spec'ed.

 

[rerig]

The Hangar power unit provides both AC & DC power through a singel plug to the aircraft.

 

[PHovnanian]

As to that 28 Vdc unit, you'd better check the details on this one. Through the 747-400 model, only 400 Hz 200/115V was provided to the external power receptacles (two per airplane).

28 Vdc may have been used for some maintenance procedures when the batteries were removed. As such, that system might be portable.

But then again, things may have changed with newer models.

Also, in that photo posted by rerig, on the 747-400, the two smaller pins in the plug are for a control circuit that de-energizes the ground power source in the event someone starts to pull the plug out hot. The corresponding pins in the aircraft are shorter than the 4 AC pins.