Tait TB9100, Installation And Operation Manual

Page: 114 / 144

114 Technical Description TB9100 Installation and Operation Manual
© Tait Electronics Limited May 2006
Auxiliary Power
Supply
This optional power supply board is mounted on the DC module. The input
power is provided from the PA output of the HVDC circuitry on the AC
converter board. It provides a high quality 13.65 VDC, 27.3 VDC or
54.6VDC output (depending on the model) to power external accessory
equipment, or can be used to trickle-charge batteries. It can be configured
using the CSS to operate whenever mains voltage is available, or whenever
the PA output is available.
Note
While the auxiliary power output can be used for more than one
purpose at once, this is generally not recommended. It can result
in a short-circuit and equipment damage. The output is floating.
If it is connected to a negatively earthed battery and to positively
earthed auxiliary equipment, it will short-circuit.
Microprocessor
The microprocessor on the HVDC control card monitors and controls the
operation of the PMU. There are no manual adjustments in the PMU
because all the calibration voltages and currents required to control and
protect the PMU are monitored by the microprocessor. The software also
automatically detects the PMU configuration and controls the PMU
accordingly.
If any of the monitored conditions exceeds its normal range of values, the
microprocessor will generate an alarm and take appropriate action,
depending on the configuration of the PMU.
The alarms and diagnostic functions are accessed through I
2
C bus messages
on the system control bus via the reciter, control panel and CSS.
The operation of the cooling fan mounted on the front panel is determined
by the temperature limits set in the PMU software.
Important
In base station systems that use a PMU, the PMU must be
connected to the system control bus at all times. The I
2
C
current source is located in the PMU, and if the PMU is
disconnected, the state of much of the bus will be unde-
fined. This may cause corrupted data to be present on the
bus when the reciter reads the states of the switches on the
control panel. This in turn may result in random actuations
of microphone PTT, and carrier or speaker key, causing the
base station to transmit, or the speaker to be actuated,
incorrectly.
Indicator LEDs
The indicator LEDs on the front panel are used to indicate the state of the
PMU and its microprocessor. There are two LEDs, one red and one green.
Each LED can be on, off, or flashing at two rates (fast or slow). The state of
these LEDs can indicate a number of operating modes or fault conditions,
as described in
Table 8.3 on page 115 .