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Description
TB9400/TN9275 Installation and Operation
© Tait International Limited May 2023
1.8.6
Front Panel Fans
The front panel is equipped with three fans. One fan is for the PMU, and
the other two are for the reciter/PA pairs in a 50W base station, or for the
PA and reciter in a 100W base station, or for the receivers in a receive-only
base station (refer to
“Appendix C Identifying Front Panels” on page 137
).
Front panel fans do not operate continuously, but are switched on and off
as needed. The PMU and PA control their own fan. Reciters request the
front panel to turn on their fan. The reciter in slot 1can also carry out a fan
test on all three fans.
Front panel fans are 3-wire fans (power, ground, and rotation detect). The
reciter can monitor whether the fans are rotating and generate an alarm if
any of the fans fail.
The fans turn on for the duration of time the base station takes to boot
from power up. The fans also turn on for a few seconds after the front
panel is refitted to a base station that is powered up.
Configuring Fan
Control
The operation of the PA fan is configurable via the WebUI; you can specify
the threshold temperature at which the fan will be turned on, and set the fan
to operate only when the PA is transmitting.
Notice
If a fan is not operational, the fan alarm will only be raised
when the fan is turned on, not at system start-up. To avoid discovering
a fan fault after leaving the site, Tait recommends running a diagnostics
fan test.
The PMU fan has fixed on/off thresholds and a defined set of duty cycles
based on the PMU temperature and load current, as described in the
following table.
PMU Temperature
Current
Fan Duty Cycle
<149°F (65°C)
<4A
4A–6A
6A–8A
8A–12A
12A–14A
15A
always off
2 minutes on, 8 minutes off
2 minutes on, 5 minutes off
3 minutes on, 3 minutes off
4 minutes on, 1 minute off
always on
>149°F (65°C)
––
always on
