ATR 42-500, Manual

Page: 112 / 129

Annexes
p. 111
UNDV
DC STBY <19.5V. No CAP.
OVRD
Transfert of STBY buses from
HOT MAIN to HOT EMER BAT
BUS.
INV FAULT
Inv failure or supply loss
Auto-Xfer of all AC buses to
remaining inverter. CAP.
Emergency supply indicators
(Amber arrows) (Respective
battery discharging).
ON
Pb pressed IN (ON illuminated
WHITE). TRU is connected
to ACW BUS 2 – ARROW
illuminates amber when supply
of DC EMER BUS, DC STBY
BUS, INV 1 (AC STBY BUS)
and DC ESS BUSS from TRU is
effective.
FAULT
Battery charger failure detected
by MFC. CAP.
Contactor Auto opens (MFC) if:
thermal runaway/Bus voltage
<25V / start sequence/Bat sw
on OVRD.
Respective bus not supplied.
CAP.
SHED
One of the DC SVCE / UTLY 1
and 2 busses is shed (BPCU).
CAP.
OFF: all the DC SVCE BUS/
UTLY 1 and 2 busses are shed
Opposite generator has not
come on line to assist start at
10% NH (on ground only).
Generator FAULT LT
Extinguishes above 61.5% NH
if GEN is operating normally.
On external power, pedestal PB
must be on to power CVR test
Associated bus deenergized.
CAP .
OVRD
insures basic mode operation
by overriding all other
protections.
ON
Basic mode: STBY Busses
supplied by HOT MAIN BAT BUS.
EXT or GEN power: DC
STBY BUS transfered to HOT
EMER BAT BUS; AC STBY
BUS to DC BUS 1.
OFF
ESS BUS, DC STBY BUS +
INV 1 are isolated from HOT
MAIN BAT BUS.
DC EMER BUS is isolated
from HOT EMER BAT BUS.
Allows BPCU to control BTC
operation (Bus Tie Contactor).
Ext power, Hotel mode or
single gen operation. BTC is
closed (green flow bar).
ISOL
BTC opened (released out).
BTR (Bus Tie Relay) locked
open (Tie between AC Busses)
AVAIL
GPU has been checked by
BPCU for over/under voltage,
over current and polarity.
AVAIL + ON
The GPU supplies the
electrical system. GPU has
priority on both generators.
FAULT
Protection triggered by GCU.
Auto reset if underspeed: in
other cases manual reset.
BTC auto closes.
ON
started engaged. At 45% NH,
light out, starter disengages
automatically.
CRANK
dry monitoring (no ignition).
START
selects a start sequence.
In flight regardless of start
selection (A, B, A+B) both
exciters are energized.
FAULT
illuminates when:
starter remains ON with
NH>45%
or GCU failure during start
or starter failure
or ENG2 only PROP BRK
ON+Gust lock not engaged
(Starting not inhibited).
ON
Continuous ignition (both A & B).
Memo panel light.
READY
engagement or
disengagement cond. Are met:
– A/C on ground
– gust lock engaged
– CL on FTH of FUEL S/O
– blue hyd press > 2100 PSI
– fire handle not pulled
PROP BRK
Prop brake fully locked.
Memo panel light.
Prop Brake not fully locked or
not fully released. After 15 sec
=
CAP .
Supplied by ACW.
Supplied by DC SVCE BUS
(Back up DC BUS 1).
Supplied by DC BUS 2.