Technical Handbook

Table Of Contents
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Figure 8-8 The IIC serial bus and ADC channels.
8.7 Power Supply
The ILS main cabinet is supplied from one or two 27V power supplies with a backup battery.
The 27V is regulated down to
±
15V, 8.5V and 5V. The transmitter power amplifiers are fed
directly from the 27V supply, while the rest of the system uses the regulated voltages.
Current measurements are done on the power supply, the battery and each power amplifier.
Each regulated voltage is measured in the Power Supply PS1227A. The results are presented
to the user through the RMS system.
When the ILS signals are shut down, the power supply to the power amplifiers are actually
turned off by relays. This is controlled by the
terminator alarm
signal from the station control
section.
The backup battery is protected against deep discharge with a protection circuit. This circuit
disconnects the battery when the voltage drops below 22V.
A battery warning is given through the RMS system when the primary power supply (supplies)
fails.
RMA 1215A
MF 1219A
MON1
MF 1219A
MON2
MO 1212A
MON1
MO 1212A
MON2
PS 1227A #1 PS 1227A #2
LF 1223A
TX1
LF 1223A
TX1
GPA 1231A
TX1 COU
GPA 1232A
TX1 CLR
GPA 1231A
TX2 COU
GPA 1232A
TX2 CLR
CI 1210A
IIC serial
bus
ADC
channels
MF 1219A
STB MON
MO 1212A
STB MON
OS 1221B
TX1
OS 1221B
TX2
HBK571-1