BFGoodrich
Avionics
Systems,
Inc.
Component Maintenance Manual
P/N 50
1-1075-(
)
Description
and Operation
1. General
The
PS-823
Emergency Power
Supply
provides
28.0Vdc and 115.0Vac 3-phase
power for
DC or
AC
Standby
Attitude Indicators.
2.
Purpose
Of Manual
This
manual contains operation
instructions,
maintenance instructions
and parts support information
for
the Model
PS-823
Emergency Power Supply (Figure
1).
3.
Purpose Of
Equipment
The Model
PS-823
operates from
internal
nickel-cadmium
batteries or aircraft 28Vdc
power. The
outputs are l
l5.0Vac,
400
Hz,
3-phase at
100VA
(capacitor-shifted
power
for third phase);
26.0Vac,
1-phase;
and 4.5Vac, 1-phase.
All
output
power
is
in the form of a
square wave that is filtered to
meet
RFI
requirements.
The
power
supply
provides network
shifted-phase
power for a
controlled
time
to start 3-phase
gyro
motors such
as
Model
AI-804
Standby Attitude
Indicator. A
battery
charging circuit provides
a
stepped-up
charge rate
whenever the
PS-823
inverter isturned ON. The
inverter will provide
power output
from internal
battery
with
voltages
between 22.0Vdc
and
27.0Vdc.
Using fully
charged
batteries,
the Emergency
Power
Supply will
drive the respective
indicator
for the
following
specified time:
Model Indicator
*
Time (Hr)
PS823A
& E
2
inch(3 inch) 2.1
(1.0)
PS823ATI'
&
E/T
2
inch
(3 inch)
2.1 (1.0)
PS823B
&
F
2
inch
(3 inch) 4.2
(2.0)
PS823B/T
&
F/T
2 inch
(3
inch) 4.2 (2.0)
PS823C
& G 3
inch 1.0
PS823C/T
&
G/T 3 inch 1.0
PS823D
&
H 3
inch
2.0
PS823D/T
&
H/T 3 inch 2.0
*
Derate time
1
percent/degree centigrade
for ambients
above or below 25 degrees
C.
4. Physical
Description
The Model
PS-823A,
C,
E
and G contain sealed
nickel-cadmium
batteries
having a rating
of 1.9
Ampere-hours
(Ah), while the
PS-823B,D,F
and H
contain sealed
nickel-cadmium
batteries having a
rating of
3.8Ah.
The Model
PS-823
consists of a
chassis,
two circuit
card
assemblies (CCAs) and
associated
hardware,
interconnecting
wire, and electronic components.
High
power
transistors are mounted
flush on
heat sinks and CCAs are
mounted
directly
behind the heat sinks.
Connector
pins
pass
through
the
printed-circuit
board
assembly
before being
soldered
directly
to the circuit card.
msmljtp202DescriptOpsdiskl59
24-20-03
Page
l
Revision
A
June
30,
1999
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