T-45A UJPT, E2-C2, ADV, & IUT Eng-07
Electrical
II.
Electrical system operational characteristics
Sg 2, fr 1
1.4.4.2.1, 1.4.4.3
Lesson Organization
A.
DC power system: consists of two batteries,
Sg 2, fr 2 (6 Overlays)
generator, voltage regulator, overvoltage unit,
Electrical System Block Diagram
undervoltage unit, and three 28 VDC buses
1.
Power generation
a.
Main electrical power supplied by 28
Overlay 1
VDC brushless generator
Generator
(1) During ground starts, the
GENERATOR warning light will
extinguish when a suitable DC
output is obtained 25-25.2 VDC (at
approximately 42% rpm); White
Paper: may occur as high as 61%
(weak permanent magnet in
generator) (no big deal - Brits)
b.
As engine rpm or electrical loads
Overlay 2
change, the voltage regulator controls
Voltage Regulator
output voltage to 28.2-29.2 VDC by
adjusting generator excitation voltage
c.
Overvoltage protection unit monitors
Overlay 3
generator output and prevents voltage
Overvoltage Unit
from exceeding 30.2 VDC by shutting
down generator
d.
If generator goes off-line
(1) MSTR ALERT light flashes
(2) GENERATOR warning light on
WCP illuminates
(3) Warning tone sounds
NOTE: The MSTR ALERT light
and warning tone may be canceled
by pressing the MSTR ALERT
light.
Page 7-8
(8-03) Original
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