voltage maintenance - Page 2

erj-145mech · 02-24-2008, 05:13 AM

Quote:

Originally Posted by UFOGUY

Hey all, what maintains a constant voltage output from the engine generators and the apu generator? The systems book doesn't explain specifically. Is there a drive or guide vanes on the APU? I thought I knew this answer...

GCU's, or generator control units, ie, voltage regulators.

The generator drive on the APU is direct, as the gen is also the starter. There are guide vanes on the APU but they are fixed, not variable.

Morophine · 03-01-2008, 09:35 PM

erj-145mech is right on the money. There are 5 GCU's, 2 near the left relay rack, and 2 on the right relay rack to control the engine generators. The last GCU for the APU is under the center floor board as you walk into the cockpit. You can control the voltage of the generators by turning the set screws located on the top of the boxes.

IAH145CA · 03-05-2008, 10:06 AM

Quote:

Originally Posted by UFOGUY

Hey all, what maintains a constant voltage output from the engine generators and the apu generator? The systems book doesn't explain specifically. Is there a drive or guide vanes on the APU? I thought I knew this answer...

The GCU's Generator Control Units control the generator voltage. The GCU's are located under where we put our flight bags for the engine gen GCU's and the APU GCU is under the panel just aft of the pedestal

rjacobs · 03-05-2008, 10:37 AM

The GCU's are in a perfect place where if they catch on fire, you cant get to them to put them out. The hose that connects to the window track drain runs right passed the GCU's.

erj-145mech · 03-05-2008, 11:22 AM

Quote:

Originally Posted by rjacobs

The GCU's are in a perfect place where if they catch on fire, you cant get to them to put them out.

There are numerous component items on the EMB-135/145 that are that way. This is why there is ample ciruit protection in the system to prevent this.

dojetdriver · 03-05-2008, 09:24 PM

Quote:

Originally Posted by ?

No, there is a little elf who lives in every APU and when he senses an overvoltage he puts his thumb on the turbine wheel to slow it down a bit to regulate voltage

duh

He's also the same elf that deals with the baggage compartment if you get the warning. You press the button, it rings a little bell, he gets up and goes pee back there to squelch a fire.