User's Manual

Model 1150A DVOR
2-64 Rev. - November, 2008
This document contains proprietary information and such information may not be disclosed
to others for any purposes without written permission from SELEX Sistemi Integrati Inc.
Battery back-up is switched on when the diode OR’d output of diodes CR45 and CR47 (48VPS1 or 48VPS2) is too
low; approximately +43Vdc. Comparator U19 monitors this diode OR’d output (scaled by RN1 and renamed
48VPS_MON) at comparator U19-2 and compares it to the scaled +5VREF at U19-3. When 48VPS_MON is too
low, comparator U19-7 switches low which turns on isolator U2 and transistors Q1 and Q2; connecting the battery
to +48BUSS. Comparator output U19-7 also connects to diode CR11 and resistor R23 so microcontroller U8-7 may
read battery switch status as signal ~DC_FAIL.
Battery back-up will remain on until either 48VPS_MON returns or the battery discharges to below approximately
+40Vdc. Upon sensing the battery has discharged too much (BATT_VOLT mentioned previously), microcontroller
U8-25 turns on transistor Q3 which shuts off comparator U19-7, isolator U2, and transistors Q1 and Q2;
disconnecting the battery from +48BUSS. This battery cut-off prevents excessive discharge and possible harm to the
battery. The BCPS CCA (and the associated transmitter) will now be completely powered off until either AC power
is restored or the charger reset switch S1 is pressed.
Charger reset switch S1 provides a means of powering up the BCPS CCA (and the associated transmitter if the front
panel circuit breaker is closed) with no AC power available. Pressing switch S1 discharges capacitor C7 through
resistor R15, momentarily turning on transistor Q7. Transistor Q7 momentarily connects the battery through current-
limit resistor R91 and diode CR28 to +48BUSS; powering on microcontroller U8. Once microcontroller U8 detects
no AC voltage is present, it turns on battery back-up through transistors Q1 and Q2. The BCPS CCA will remain on
until either AC power is restored (shutting off battery back-up) or the battery discharges too low (battery cut-off).
System AC voltage and current as well as obstruction light (ob lite) AC voltage and current are sensed and scaled on
the AC Monitor CCA before arriving at the BCPS CCA. System AC voltage (SYS_VAC_POS) enters cPCI
connector P1-25 and is transient protected by CR23. Current limiter U13, resistor R33 and zener diode CR29
condition the signal to drive the AC_ON LED CR48. Potentiometer R30 scales while resistor R46 and capacitor
C21 filter the signal before op-amp U10D buffers it to resistor network RN5-16 and multiplexer U11-19 as
SYS_VAC_SCALED.
Obstruction light AC voltage (OB_LITE_VAC_POS) enters cPCI connector P1-23 and is transient protected by
CR24. Current limiter U12 and resistor R31 provide a constant load. Potentiometer R29 scales while resistor R34
and capacitor C22 filter the signal before op-amp U10A buffers it to resistor network RN5-12 and multiplexer U11-
21 as OB_LITE_VAC_SCALED.
System AC current (SYS_IAC_POS) enters cPCI connector P1-26 and is coupled by capacitor C45, transient
protected by CR38, and conditioned by op-amps U14A and U14D. The amplifiers and connected components act as
full-wave rectifier and filter averaging circuits. Potentiometer R56 adjusts the final gain to create SYS_IAC which is
further scaled by resistor network RN5-14 to create SYS_IAC_SCALED at multiplexer U11-20.
Obstruction light AC current (OB_LITE_IAC_POS) enters cPCI connector P1-24 and is coupled by capacitor C46,
transient protected by CR30, and conditioned by op-amps U14B and U14C. The amplifiers and connected
components act as full-wave rectifier and filter averaging circuits. Potentiometer R44 adjusts the final gain to create
OB_LITE_IAC which is further scaled by resistor network RN5-10 to create OB_LITE_IAC_SCALED at
multiplexer U11-22.
Power supplies VCC and +12ANA are scaled by RN4 before routing to multiplexer U11-10 and U11-9. Power
supply -12ANA is scaled by RN5 and inverted to a positive voltage by op-amp U10C before connecting to
multiplexer U11-8 as -12ANA_SCALED. The -12ANA is inverted because microcontroller U8 can only read
voltages in the 0-to+5V range.
Most of the analog signals of the BCPS are connected to the 16-channel analog multiplexer U11. Individual
channels are routed to output U11-28 by channel selects U11-17, U11-16, U11-15, and U11-14 which are controlled
by microcontroller U8. The multiplexer output signal U11-28 is buffered by op-amp U10B, filtered by resistor R24
and capacitor C13, and clamped by diodes CR9 and CR10 before entering an analog channel of microcontroller U8-
3.