Airflow; Figure 12-2 Mts 2 Airflow - Motorola DIMETRA MTS 2 Installation, Configuration And Basic Service Manual

Airflow
Airflow
MTS 2:
The 2 BR card cage has a clear opening in the bottom front and small holes in the side and back. Ambient
airflow enters at the bottom of the front, back and sides and passes up through the modules. The optimal
solution is to allow the air inlet from all sides. At the top of the card cage there is enough space for the air to
distribute and spread. It then passes up through the filter section and out of the venting grill at the top. If there
is nothing in close area to sides, the air can also exit here. The airflow routing is the same with or without fans.
Figure 12-2 MTS 2 Airflow
MTS 4:
In MTS 4 the airflow is different. The additional depth and width of the cabinet are used to guide and
separate ambient air intake and heated air outlet. For both card cages the main airflow of ambient air
enters at the front. At the bottom card cage the air can enter from all sides. For the top card cage the
air has to pass in front of and behind the bottom card cage. In the front, between the modules and the
cabinet door. In the back, between the bottom card cage back and the back of the cabinet. The flow is
obstructed by an insert which guides the hot air from the bottom card cage out to the sides and up between
the top card cage and the cabinet sides. The exhaust from the top card cage could be partly obstructed
by a Cavity Combiner situated above. The exhaust can occur on all sides. No obstructions are inserted.
Due to the obstructions in the airflow, fans are required for all configurations of MTS 4.
The fans have a low rpm alarm indication. Each fan module (part no. 0166501N50) has two fans
inside. In case of failure, one of the fans still gives an airflow. Therefore the fan module is not
considered a periodic maintenance component, but is only replaced when it fails.
12-4
Chapter 12: Cooling Fans
6802800U74-N September 2009