AC/DC powered aircraft

[dkelly]

Hey everyone. I'm doing a report on ground power units and am trying to find info on what particular aircraft are DC powered and AC powered. Different Makes and Models would be extremely helpful, thanks in advance.

 

[mcjohn]

Man that was just wrong! I'm an AC/DC powered pilot!
HEAD OUT ON THE HIGHWAY!!!! GOIN TO THE SHOW!!!! The bagpipe solo is the sh!t!

SORRY. I just got the new box set!
http://www.acdcrocks.com/

Hey aussiefly....it's your freakin country. What town is that where they filmed "It's a Long Way to the Top if Your Gonna Rock and Roll?" with the bagpipes and all.

 

[KeroseneSnorter]

Most large airplanes are both. Meaning that they have both AC and DC components. And in many cases DC controlled AC systems. Most turbine mounted generators put out AC power, that is then converted to DC for the various needs as required.

However speaking from a GPU point of view, most are ac and converted to DC.....well anything that has to do with the battery system anyhow, since I am sure you know that AC power cannot be stored in a battery.

Short answer, most use ac hookups, but use inverters or Transformer rectifier units to convert the power to what ever the various systems require.

Clear as mud huh?




EDIT: To try to unconfuse you.....generally speaking glass video screens, fms's, and electric anti ice systems (windshields, non bleed air hot wings etc) are AC powered. As well as all of the large energy consumpsion items.

Avionics not included in the above, lights, switch controls and such are generally DC powered. For example, an AC powered heated windshield might be controlled by a DC powered switch.

Transformer converts AC to DC Power.
Inverters convert DC to AC power.

Humm,, I am way too freaken bored tonight, at any rate, Boeing 747 uses 115 +-5 volts, 400 +-5 hertz AC power with a GPU requirement of 250 amps.

 

[Junkflyer]

Large jets use 115 volt/ 400 hertz a/c power. The gpu has a fat plug that goes into a 6-pin receptacle.

 

[Flyerjosh]

Here's some info about the two aircraft that I am familiar with...

CRJ- 115volt AC primary power system (generated by APU and Engine driven generators), 28 volt DC secondary power system (generated by transforming AC power to DC power through 5 transformer rectifier units). Emergency backup to essental AC power items through an air driven generator. 7 AC power busses, 10 DC busses. Two ports for external power (AC is primary ground connection and can power the entire system. DC is secondary and can be used for engine or APU starts in the event aircraft batteries are drained).

Cessna Citation 560 (Encore)- 30 volt DC primary system (regulated to 28.5 volts/300 amps), powered by two engine driven DC generators. AC power for avionics systems (115 volt) and other AC systems (26 volt) provided through two inverters. Emergency power through main battery (provided in either "normal" mode in which everything is powered by the battery for ~10 minutes, or in "emergency" mode in which only essential systems (backup instruments/comm-nav 1/ basic flight systems are powered for ~30 minutes). One external power connection for DC power cart which can power entire electrical system.

 

[dkelly]

thanks

Thanks for the replies guys. That is exactly what I was needing flyerjosh. any other aircraft types would be great...

 

[NuGuy]

Heyas Dkelly,

Some of your smaller turboprops usually will have DC power.

The Beech 1900 and 99 had DC starter/generators, which were just switchable motor generators. Connected one way they acted as starters, and the other way they acted as DC generators. For the few avionics that used AC power, there was a static inverter (actually, a main and a spare) that converted DC to 400hz AC. Both the 1900 and 99 used 28v DC ground power.

The DHC-8 also had DC system as it's "primary" electrical system. But it also had static inverters for avioincs and variable frequency AC generators for high draw AC items like inlet and windshield heat. The variable AC system could also power the DC system through TRUs. The whole thing was pretty complicated, but super robust. The DHC-8s that I flew had both AC and DC power recepticals, but I never saw the AC used, and all the carts I saw were DC carts.

As you move into larger aircraft, everything is mostly 3-phase 115v AC juice with either constant speed drives or integrated drive units (to maintain a constant RPM) with TRUs generating any DC power necessary, and all external is AC, although I did see a few DC-9s with DC external power provisions, but it was never used.

Nu

 

[twighead]

Heyas Dkelly,

The DHC-8s that I flew had both AC and DC power recepticals, but I never saw the AC used, and all the carts I saw were DC carts.

Nu

the AC ground power for the dash 8 is really only used by maintenance.

 

[njcapt]

The 737-200 had both AC and DC external power plugs. Most people weren't aware that it had the DC one, but I got to use it one time when we otherwise would have been stranded.

Back when I was at Vanguard, we used to repo the 737 to a remote ramp for a RON at MDW. I was picking up the aircraft one cold morning, and the battery was depleted enough that it wasn't legal to start the APU. Added to the miserableness factor was the fact that the AC external power plug was deferred by MEL (some yahoo tried to drive away the GPU while it was still attached to the aircraft). I remembered the DC plug in the E&E compartment, had the FBO hook up DC power and, once the APU was started, away we went - on time. I rule!

Actually, I think the FO remembered it first, but why let facts get in the way of a good story.

 

[Geronimo4497]

Pilatus PC-12 uses DC ground power. Most systems are DC (sans avionics, which use inverters). G-IV has provisions for both DC and AC ground power. I have only seen one gas fired GPU with both an AC and DC plug. The rest were powered by electrical connections to the building's power. I worked at a small FBO, however. Hope that helps.

http://hobartgpu.com/