User's Manual

Model 1150A DVOR
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.
2-61
2.3.2.18
Power Panel Theory
Refer to Figure 1-3. The power panel, located on the lower front portion of the electronics cabinet, contains the AC
input the Battery input and DC Buss circuit breakers for Transmitters 1 and 2. AC input power for the Transmitters
enters the cabinet via the AC Monitor (REF DES 1A6) terminal block 1A9TB3 terminals 1, 2 and 3. AC input
power for the Outlet and obstruction lights enters the cabinet via the AC Monitor (REF DES 1A9) terminal block
1A9TB2 terminals 1, 2 and 3. Positive DC input power wires from the optional battery backup (unit 3) enter the
cabinet via J1 (blue connector) on the back of the power panel assembly. The negative DC input power wires
connect directly to the ground bus bar. Circuit breakers 1CB1 and 1CB4 control the application of AC voltage to
Transmitters 1 and Transmitter 2 BCPS systems. Circuit breakers 1CB2 and 1CB5 control the application of battery
power to Transmitters 1 and Transmitter 2 BCPS systems respectively. Circuit breakers 1CB3 and 1CB6 control the
application of power from the BCPSs to Transmitters 1 and Transmitter 2 racks 1A3, 1A4 and 1A5.
2.3.2.19
Battery Charger Power Supply (BCPS) Theory
The BCPS assemblies provide regulated voltage to the transmitter from either the AC input or the batteries. The
BCPS assemblies are located in the third rack. The AC voltage is an input to the BCPS which converts to
approximately 50 Volts DC. The BCPS assemblies are also responsible for charging the batteries when AC is
present.
2.3.2.19.1
BCPS CCA Block Diagram Theory
Refer to Figure 2-23. The Fanless BCPS CCA provides battery-backed DC power to all associated TX1 or TX2
modules in the cabinet as well as monitor and charge its associated battery stack. The Fanless BCPS CCA connects
to the Carrier Backplane CCA through compact PCI (cPCI) connector P1.
100-260VACrms, 47-63Hz power enters through the cPCI connector P1, is fused and RFI filtered before being
converted to approximately +51Vdc by brick PS3, then is routed to bridge diode CR1. Bridge diode CR1 OR’s this
DC output with that of the other BCPS in the cabinet (if optionally wired on the Carrier Backplane) for redundant
operation.
The DC output of bridge diode CR1 is measured by op-amp U1 across current-sense resistor R2 and reported to
microcontroller U8 through analog multiplexer U11. This DC output (+48BUSS) routes several places.
+48BUSS powers DC-DC converters U15 and PS2 through fuse F1. These DC-DC converters create +5Vdc,
+12Vdc, and -12Vdc for powering on-board circuitry.
+48BUSS powers DC-DC converter PS1 through fuse F2 to create +54.2Vdc for charging of the batteries. DC-DC
converter PS1 can have its input power switched by transistor Q11 and its output power switched by transistor Q5;
both under the control of microcontroller U8. Battery charging is stopped for short times periodically to switch on
load transistor Q4 (with load resistors R6, R7, R9, and R10) to test whether batteries are connected or have become
too weak.
Battery charging or discharging current is measured by op-amps U4 and U5 across current-sensing resistor R14 and
reported to microcontroller U8 through analog multiplexer U11.
Comparator U19 monitors the diode OR’d +51V supplies (scaled by RN1 and named 48VPS_MON) and switches
on transistors Q1 and Q2 through isolator U2 when battery back-up is needed (48VPS_MON too low). Comparator
U19 will shut off battery back-up if 48VPS_MON is restored or microcontroller U8 will shut off battery back-up by
turning on transistor Q3 (which turns off U19, U2, Q1, and Q2) if the battery voltage (scaled by RN3 and named
BATT_VOLT) becomes too low; preventing total discharge of and possible harm to the battery.
Charger reset switch S1 provides a means of powering up the board (and the cabinet if the front panel circuit breaker
is closed) with no AC power available. Pressing switch S1 turns on transistor Q7 and battery power conducts
through current-limiting resistor R91 to +48BUSS.