T-45C TS, ADV & IUT ENG-27/ENG-28
Engineering Review
c.
Undervoltage unit
Sg 5, fr 7
Undervoltage Unit
(1) At 25 volts or less deenergizes
(a) On aircraft 165456 and below without
AFC 199
(i)
Activates relay disabling one
inverter illuminating AC INV
caution light
(ii) Activates relay disconnecting non-
essential AC bus
(b) On aircraft 165457 and up and on
aircraft 165456 and below with AFC
199 incorporated
(i)
Both inverters remain on-line and
AC INV caution does not
illuminate
(ii) Activates relay disconnecting non-
essential AC bus
(2) Functional: monitors voltage on generator
bus
(3) Physical: consists of transistorized voltage-
sensing, time-delay circuit and changeover
relay
5.
Power protection
a.
Fuse connects generator to 28 VDC generator
Sg 5, fr 8
bus and provides 300 amp generator protection
Fuse
b.
Buses and circuit breakers
(1) Three essential buses (two AC and one
Sg 5, fr 9
DC) powered by battery power if generator
Essential Buses
fails -- e.g., IFF, fire detection, warning and
caution advisory panels, and UHF/VHF #1
(2) Three non-essential buses (two AC and
one DC) drop off the line if the generator
fails
(9-98) Original
Page 27-9
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