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.
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2.3.2.13.1
AC Power Monitor CCA Block Diagram Theory
Refer to Figure 2-15. The AC Monitor provides a method of measuring the AC voltage for the Transmitter and
obstruction light circuits individually. A step down transformer with a full wave rectifier is provided for each
channel. The AC current for the Transmitter and obstruction lights travel through individual current transformers.
The resultant AC voltage is provided to the BCPS CCA for rectification and current to voltage conversion.
2.3.2.13.2
AC Power Monitor CCA Detailed Theory
Refer to Figure 2-15. The AC Power Monitor CCA provides a means for the VOR system to measure the AC
current and voltage levels of the obstruction lights and of the VOR system itself.
NOTE
The Schematic for the 012186-0001 Circuit Card Assembly differs from the labeling on the
mechanical housing. The terminal strips TB4 and TB5 are numbered in the opposite
direction on the housing. This theory of operation follows the numbering on the schematic.
T2 is a current-sense transformer in series with the obstruction lights line supply from TB2-1 and TB1-2. AC current
through the primary of T2 induces a current in the secondary. The secondary is connected to J1-3. A resistor on the
AC Monitor CCA converts this current to voltage for measurement.
T3 is a voltage step-down transformer connected in parallel to the obstruction lights supply at TB1-1 and TB1-3.
The transformer primary is strapped to accept a nominal 220 VAC. AC voltage on the primary is stepped-down on
the secondary. The secondary is center-tapped and diodes CR1, CR2, CR5 and CR6 act as a full wave bridge
rectifier and the rectified output is routed to J1-1.
T1 is a current-sense transformer in series with the VOR’s line supply from TB3-1 and TB4-1. AC current through
the primary of T12 induces a current in the secondary. The secondary is connected to J1-7. A resistor on the AC
Monitor CCA converts this current to voltage for measurement.
T4 is a voltage step-down transformer connected in parallel to the VOR’s supply at TB4-1 and TB4-2. The
transformer primary is strapped to accept up to 220 VAC. AC voltage on the primary is stepped-down on the
secondary and it. The secondary is center-tapped and diodes CR3, CR4, CR7 and CR8 act as a full wave bridge
rectifier and the rectified output is routed to J1-5.
An external jumper must be connected at TB1-1 to TB1-2 if a photo cell switch is not connected in series with the
obstruction lights. If a photocell is used then a wire must be connected from the output side of the photocell back to
TB1-1.
Earth ground is also connected to the AC Monitor CCA via the board’s mechanical mounting holes.