Cooling Fans Theory Of Operation; Figure 12-1 Mts Fan Kit - Motorola DIMETRA MTS 2 Installation, Configuration And Basic Service Manual

Cooling Fans Theory of Operation

Figure 12-1 MTS Fan kit

Cooling Fans Theory of Operation
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The 2BR card cage is able to contain fan kits which reside below the modules. The three fan kits
are supplied and controlled from the PSU with variable speed control. This is in order to reduce
the noise in normal temperature environments. The Fan speed is based on the temperature of the
modules. The latter require that the Site Controller software monitors the module temperatures
and through the CAN Bus controls the speed of the fans.
MTS 2 offers configurations which do not need fans. The temperature range is from -30 °C to 55 °C. If the
temperature range is extended to 60 °C three fan kits needs to be mounted. MTS 4 requires fans for all
configurations. There is no need for fans in MTS 2 for the low power PA BTS configurations. In other
configurations three fan kits are needed at the bottom of the card cages. There may be a reliability issue with
the fans if operated below -10 °C. At an ambient temperature below -10 °C the fans are stopped and restarted
again at -8 °C. The fan supply ramps up to 24 V output for a few seconds in all start up situations.
12-2
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Chapter 12: Cooling Fans
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6802800U74-N September 2009