737 residual voltage

[saviboy]

a friend of mine is studying 737-200 elec system and asked what s residual voltage.

the only explanation I found that made sense to me was non aviation related:

residual voltage is the voltage produced at the null position.

the way I see it is that when the rotor is cutting the lines and is parralel to them,

its supposed to produce 0 volt. whatever is produced is residual voltage

am i right?

thanks

 

[avbug]

Too many big words. Residual voltage is what's left over when the generatoris turning but no field current is applied. Many systems utilize reset buttons which "flash the field," to restore power to the generator. This is usually accomplished through a GCU, or generator control unit. the GCU acts like a big voltage regulator...it suppliesand regulates "field current" to the generator to tell it how much electricity to produce, and thereby regulates the voltage. When this field current isn't supplied, the generator still has a very low output. Ordinarily you won't see this on the aircraft electrical voltmeters when they're attached to the batteries or any particular bus being powered by a generator or battery, because the highest voltage being applied to that point is what's indicated.

If you're sampling generator voltage only, however, and all you see are about one point five to three volts, you're looking at residual voltage...what the generator is putting out without any outside help or control.

Think of the generator as your wife. Operating voltage is her go out on the town face. Residual voltage is what she looks like all by herself, in the light of day, in the morning when she first wakes up.

I haven't had much sleep.

 

[saviboy]

thanks for the reply.

i think i understand.
why would you monitor that ?

according to my firiend there is a voltmeter in the 737 200 for residual voltage

 

[scoreboard]

To check that when you decouple the generator that it is not spinning, if there is a residual voltage, it is spinning and means the CGB is still driving the generator, a bad thing when you want it unhooked for high temp.

 

[saviboy]

thanks guys got it