Service Manual

GSM-204-323
Thermal management system (TMS)
31st Oct 01
Technical Description: Horizon macro outdoor
68P02902W02-A
CONTROLLED INTRODUCTION
Tech. 3–3
Thermal management system (TMS)
TMS overview
The equipment installed in the cabinet emits heat, which must be removed in
order to maintain the correct working temperature.
The thermal management system (TMS) unit maintains the cabinet internal
temperature within the operational range of the installed equipment, provided
the external ambient temperature is within the range of –40 °C to +50 °C.
An alarm is generated if the return air temperature from the BTS enclosures
exceeds 68 °C.
The TMS unit contains:
 Two recuperators.
 Two ambient air fans (external fans).
 Two recirculation air fans (internal fans).
 Two ac electric heater elements.
 One TMS control board.
 Two temperature sensors.
View of TMS
unit
Figure 3-1 shows a view of the TMS unit with airflows indicated and access
panels and air ducts omitted for clarity.
RECIRCULATION
AIR FANS
AMBIENT
AIR INLET
AMBIENT
AIR OUTLETS
AMBIENT
AIR FAN
RECIRCULATION
AIRFLOW
AMBIENT
AIRFLOW
KEY
LOCATION OF
THE TMS
CONTROL BOARD
Figure 3-1 View of the TMS unit