laptop power
Nov 17, 2004, 6:09 pm
#1
Original Poster
Join Date: Oct 2003
Location: Europe
Posts: 45
laptop power
Hi all,
I'm on QF6 and QF52 in late december, and was wondering about laptop power in J. The QF homepage says that only the skybed seats have AC power, the rest have empower. Is this correct, I thought I read somewhere all longhaul 747's have AC power.
Cheers
Chris
I'm on QF6 and QF52 in late december, and was wondering about laptop power in J. The QF homepage says that only the skybed seats have AC power, the rest have empower. Is this correct, I thought I read somewhere all longhaul 747's have AC power.
Cheers
Chris
Nov 17, 2004, 7:08 pm
#2
Join Date: Nov 2004
Location: SYD
Programs: QF Plat & Lifetime Gold, Velocity Gold, SQ PPS
Posts: 247
As far as I know all the older style business seats have DC only. Skybed was the first time Qantas introduced AC.
I always wondered why the airlines bothered to introduce DC in the first place. Creating 110 V AC in the air doesn't seem like a big technological challenge.
Mark
I always wondered why the airlines bothered to introduce DC in the first place. Creating 110 V AC in the air doesn't seem like a big technological challenge.
Mark
Nov 18, 2004, 12:58 am
#3
Join Date: Aug 2001
Programs: AA Plat & LTG; QF LTG
Posts: 9,837
Those flights would still expect to be Dreamtime business class seats in December. The Dreamtimes have Empower DC power available.
The reason AC power was not previously provided is the way sufficient and suitable AC power is generated on board. The aircraft systems that require AC power operate at 400 Hz. The reason for that is the amount of ferrous material needed in transformers and the generator itself is greater for lower frequencies. So a 400 Hz generator is a lor lighter than a 50 Hz generator. The 400 Hz AC systems could easily be used to provide DC power of any required voltage.
The 50Hz power provided in the seating cabins (J and F) is not generated at 50Hz by traditional rotary generators. That is still done in the engines at 400 Hz to keep the weight down. It is then converted to DC power and then back to 50 Hz AC via a solid state inverter. Inverter and switch mode power supply technology has imporved in recent years to become more efficient and hence suitable for use on aircraft without large weight or heat issues.
For example, not too many years ago large power amplifiers needed large and heavy transformers in their power supplies. It was difficult, expensive and very bulky and heavy to build a power amplifier much over 1000 watts. Today, you can easily purchase a unit including 4 x 1000W amps in a single rack unit space. This is all due to improvements in the efficiency of high capacity switch mode power supplied, and it is this technology that is used to provide 50Hz AC power to the aircraft cabin.
The reason AC power was not previously provided is the way sufficient and suitable AC power is generated on board. The aircraft systems that require AC power operate at 400 Hz. The reason for that is the amount of ferrous material needed in transformers and the generator itself is greater for lower frequencies. So a 400 Hz generator is a lor lighter than a 50 Hz generator. The 400 Hz AC systems could easily be used to provide DC power of any required voltage.
The 50Hz power provided in the seating cabins (J and F) is not generated at 50Hz by traditional rotary generators. That is still done in the engines at 400 Hz to keep the weight down. It is then converted to DC power and then back to 50 Hz AC via a solid state inverter. Inverter and switch mode power supply technology has imporved in recent years to become more efficient and hence suitable for use on aircraft without large weight or heat issues.
For example, not too many years ago large power amplifiers needed large and heavy transformers in their power supplies. It was difficult, expensive and very bulky and heavy to build a power amplifier much over 1000 watts. Today, you can easily purchase a unit including 4 x 1000W amps in a single rack unit space. This is all due to improvements in the efficiency of high capacity switch mode power supplied, and it is this technology that is used to provide 50Hz AC power to the aircraft cabin.