Kingfisher Plus+ Hardware Manual
3.2.3 Theory of operation
A combined block-diagram of the PS-x2 and PS-x1 modules is shown on the picture below.
PS-x2/PS-x1 Block Diagram
When Mains power is supplied to the SMPS, it generates a DC output voltage on the internal
+12V_RAIL of the PS-x2/PS-x1. Voltage level on this rail is controlled by the microcontroller
(MCU). Supply Current Sensor is used to measure current supplied by the SMPS.
When 12VBP SWITCH is activated, power from the internal rail is fed to the backplane and
to the 5VBP converter that powers 5VBP rail on the backplane, providing power to all
modules installed there. Both 12VBP and 5VBP outputs are connected to the backplane
outputs via ideal diodes that allow for redundant connection of the PS-x2/PS-x1 modules.
24VAUX ISOLATED Converter (option ‘-C’ only) and 12VAUX SWITCH can be switched ON
and OFF with user logic, providing power to the corresponding outputs of the field connector
as required.
Any device connected to the ‘B’ terminals of the Field Connector (J22 for PS-x2; ), including
a battery, is connected directly to the in12V_RAIL of the PS-x2/PS-x1. Battery
Current Sensor is used to measure current flowing to or from ‘B’ terminals. Assuming that a
battery is connected to these terminals, positive current flows into the battery when it is
charged and negative current flows out of the battery when it supplies power to the RTU.
The PS-x2/PS-11 battery input has a crowbar protection circuit with series polyfuse to
protect it from over-voltage and reverse-polarity connection. The crowbar protection circuit
will latch when its voltage is either below -0.5 V or above +18.5 V (approximately). It will
clamp the input power rail voltage to a very low value: ± (0.5 – 2.5) V depending on the
clamp current supplied by a power source. If the power source can provide current
exceeding a polyfuse trip current (2-16 A depending on the ambient temperature, see the
RUE(F)400 fuse
for further details), it may trip also, limiting the clamp current
to several milliamperes. To recover protective circuit after tripping, the input voltage should
Hardware Manual Version 7.16
http://www.servelec-semaphore.com/
Page 39