B747 400Hz Power Supply

[ElecDar]

We are designing aircrafts hanger that will accommodate seven aircrafts including B747 and in future A380, my questions are :
- What is the power supply required (400 Hz) for B747 and A380 and does the aircraft consume the full 400Hz power supply during parking or maintenance.
- Is there a rough estimate for the power required for the electrical operated equipment in the parking/maintenance hangar

 

[jcai]

GOOD MORNING - THE B.747-400 IS GENERALLY SUPPLIED WITH 140KVA - AND THE USUAL AIRCRAFT 208 V /115V /400HZ - BUT SOME AIRLINES PREFER 180 KVA G.P.U. /F.C.U. - IT DEPENDS ON WHAT GALLEYS / AIRCON ETC. THEY HAVE AS O.E.M. -IT IS OF COURSE A DUAL BUSS / DUAL FEED AIRCRAFT AS ARE MOST OF THE MODERN WIDE BODY TYPES .
THE A. 380 IS MOOTED TO BE 360 KVA - WITH QUAD BUSS FEED .
WELL BELIEVE IT OR NOT BUT IT DEPENDS ON WHAT CIRCUIT BREAKERS YOU CLOSE AS TO WHAT POWER ANY AIRCRAFT PULLS !
THE POWER USED IN THE HANGAR IS USUALLY NOT AS MUCH AS THE RAMP ON PREFLIGHT . BUT YOU HAVE TO ALLOW FOR THE WORST POSSIBLE CASE - SUGGEST YOU TALK TO A SPECIALIST OLDER EXPERIENCED 400HZ SYSTEM MANUFACTURER LIKE HOBART TROY -OHIO -

http://www.hobartgroundpower.com

- i think thats right - I DO NOT RECOMMEND THE OLDER TYPE CENTRALIZED SYSTEM - BUT INDIVIDUAL F.C.U.s FOR EACH AIRPLANE BAY .
ALL THE BEST J.C.

 

[WoodrowJWeen]

I'm interested in why jcai recommends individual frequency converters vs a centralized system. I have a client who needs 400hz power to a number of airliners parked out on a maintenance ramp. My initial response was to suggest 60hz, 480V distribution from utility padmount transformers out to FCUs at each plane (or every two planes). Some vendor suggested instead, that the client use a central system mounted in a small blockhouse with long runs out to gateboxes at each plane. I think the voltage drop at 208/120V, 400hz will be riduculous. I've heard some people distribute 400hz at 960V or some other odd voltage. Any thoughts?

 

[jcai]

GOOD MORNING FOLKS
AFTER 51 YRS AS AIRPLANE ENGINEER ELECO - ALSO INDUSTRIAL ELECO - I HAVE SEEN MANY CHANGES IN AIRPLANE ENGINEERING DESIGN AS YOU WOULD IMAGINE - I AM NOT BRAGGING - BUT I JUST WANT TO WALK YOU THRO THE BASIS BEHIND WHAT I SAID - THE MOST IMPORTANT THING TO REMEMBER WHEN POWERING UP B.747-400ER TYPEs OF AIRLINER - IS THAT THEY ARE NOT DUMB LOADs - SO YOU HAVE TO START AT THE AIRPLANE LOAD OF ARO. 150 KVA CONT. FULL LOAD - AND WORK BACK . IF THE BOEING DOES NOT LIKE WHAT IT SEES ON ITS LOAD COMPUTER - IN REGARDS TO PURE SINE WAVE - PHASE VOLTAGE BALANCE - FREQUENCY RESPONSE TO TRANSIENTS ETC. - IT WILL REJECT GROUND POWER -ALSO YOU DO NOT FORCE THE POWER INTO THE BOEING - IT TAKES IT WHEN IT IS GOOD + READY VIA ITS E+ F CONTROL INTERFACE SYSTEM - THIS ESCAPES MANY ELECO CONSULTANTS . THEY DONT SEEM TO UNDERSTAND THAT THE BOEING / AIRBUS ETC. AIRPLANE HAS TO RETURN 28.5V. D.C. BACK TO THE F.C.U. - VIA ITS T.R.U./ NI CAD BATT. - BEFORE THE F.C.U. CAN PROVIDE 400HZ POWER TO THE AIRCRAFT - THAT IS MANDATORY INTERNATIONAL AVIATION SAFETY FEATURE WE HAVE USED IN AVAIATION INDUSTRY FOR MANY YEARS . IT HAS NOUGHT TO DO WITH LOCAL ELECTRICAL REGS IN YR COUNTRY . THIS IS BOEING RULES NOW !
SO ON THE MODERN AIRLINER OR MILITARY AIRPLANE WE NOW HAVE E.F.I.S. FLIGHTDECKS + N.B.P.T. SYSTEMS + LARGER LOADS APPEARING - THE NEW A.380 IS MOOTED BY AIRBUS TO PULL 360 KVA ! THE TRANSIENTS LOADS ARE ALSO SUBSTANTIAL - AIR / HYDRAULIC PUMPS + FREIGHT DOORS OPENING CAN AND DO PULL 60 KVA IN m/s - YET THE FREQUENCY + 208 /115 VOLTAGE NEEDS TO STAY WITHIN THE BOEING SPEC D6-44588 /D623U001 .
SO THE SHORT ANSWER IS THAT ,YES - YEARS AGO WE WERE HAPPY WITH A CENTRALIZED SYSTEM RETICULATED OUT AT 960 V. VIA ROTARY F.C.U.s OR LATER ON VIA S.S. F.C.U.s .
ONE OF THE PROBLEMS WITH THAT IS THAT THE CABLING THAT HAS TO BE USED IS 6 ARO 1 TYPE WHICH IS NOT A FAMILIAR TYPE OF CABLE TO MOST ELECOS / CONSULTANTS . IT IS A VERY EXPENSIVE WAY TO TACKLE THE PROBLEM -IT OBVIOUSLY COSTS LESS TO RETICULATE NORMAL 50 OR 60 HZ POWER USING NORMAL LOWER COST CABLES - TO THE F.C.U. - THAN TO RETICULATE THE 400HZ - AND YOU CANNOT USE THE NORMAL ELECTRICAL CALCs. THAT YOU USE ON 50 OR 60 HZ FOR V.D. ETC.! THE B.747-400 NEEDS 2 X SEPERATE FLEX CABLES TO FEED IT - EACH AN3430 CONN. IS CAPABLE OF 90 K.V.A. MAX. THE A.380 USES 4 X AN3430 CONNS.
OVER RECENT YEARS WE AT HOBART HAVE USED MOSTLY A SINGLE 180 KVA DUAL OUTPUT F.C.U. AT EACH GATE - EITHER ON THE GROUND OR SLUNG UNDER THE BRIDGE . IN HANGARS WE USUALLY GO FOR MOBILE F.C.U. OR AGAIN - SLUNG UNDER THE DOCKING AT THE AIRPLANES NOSE .
WE HAVE BEEN ASKED ON SOME NEW AIRPORTS TO LOOK AT THE 960 V X 400HZ RETICULATED CENTRALIZED SYSTEM AGAIN - AS THERE ARE SOME VALID REASONS TO USE IT AND WE ARE DOING THAT RIGHT NOW IN ENGINEERING DESIGN . THE BASIS OF SUCH A SYSTEM HAS TO BE AT LEAST 1000 KVA ARO.THO - I WOULD THINK - THIS COULD POSSIBLY BE ACHIEVED USUALLY BY PARALLLING EXISTING F.C.U.s- WITH MAX DEMAND SYSTEMS INCORPORATED . BUT THEN YOU NEED STEP DOWN TRANNYS AT EACH GATE FROM 960 TO 208/115 V.
REMEMBER YOU ARE NOW WORKING IN HAZARDOUS ZONES OUT ON THE RAMP IN REGARD TO FUELLING THE BOEINGS ETC WITH JET A-1.
400HZ CAN DO NASTY THINGS TO AIRPORT SYTEMS IN REGARD TO COMMS + ELECTRICAL ETC. - WE USE OUR P.W.M. TECHNOLOGY - 12 PULSE F.C.U. TO HELP OVERCOME THIS HARMONIC REDUCTION PROBLEM . THOSE LONG 400HZ CABLE RUNS CAN AND DO BEHAVE LIKE LARGE ANTENNAES - BE CAREFUL HERE ! ESP IF SOME DINGBAT ELECO USES THE USUAL STEEL CABLE TRAY / LADDER + NORMAL 50/60 HZ CABLE SYSTEMS - DESPITE BEING WARNED NOT TO USE IT - WE SEE THAT ALL TOO OFTEN - ITS A RIP OUT JOB THEN . I HPOE THIS ANSWERS YR QUESTIONS W.W.

ALL THE BEST J.C.

 

[ElecDar]

Hi,
I have 90kVA 400Hz pit located 140m from the 400Hz converter room in a hangar (I can’t reduce the distance and the unit must be in the room).

I presume the max. allowed voltage drop is 3V, I failed to find a reasonable number/size of 400Hz cables to achieve the a/m voltage drop.

I’m proposing 400Hz line drop compensator to be located next to the 400Hz converter to overcome this problem, any comments/suggestions!

Is there a maximum length for the 400Hz cable where it will be cheaper to have LDC instead of paralleling the cables

 

[Procalc]

Good morning,
to overcome this problem simply use the "remote sense" of your fcu.
Many manufacturers have built in this function to give the opportunity to compensate the voltage drop.(but possible only on fcu´s with one output)

A LDC compensates the inductive drop only, not the resistive drop!!

All Aircrafts accept a voltage range from 118-113V, so bandwidth is 6V.

The voltage drop can be calculated by the following simple formula:
Volt.drop= cablelenght x loadcurrent x(cable resistance R x cosphi + reactive resistance XL x sinphi) / sqrt3.

The overall voltage drop in your configuration is about 15,43 V.
The calculation is based on a low losses symmetrical 7-core cable (7x35mm²) we use since many years.The considered powerfactor is cosphi 0.8.
So use 3 cables in parallel to solve the problem.

regards

 

[pitboy]

Hi,
Question to ElecDar about his 400Hz pit. What is the electrical installation code for the pit - European, NFPA?