User Manual

Cabinet descriptionNortel Networks Confidential 1–11
S8000/S8002/S8006 BTS Reference Manual
With “LN” DACS two operating modes of the twin blowers are available:
full speed mode
control speed mode. In this mode:
• if the temperature is > 45°C (113°F), the blowers run at full speed (2500 rpm).
• if the temperature is ≤ 45°C (113°F), the blowers run at slow speed
(1800 rpm).
The full speed mode or control speed mode is selected by switches located on the
control board (see Figure 1–7).
The temperature control is achieved by two high quality thermistor having an
accuracy of ±0.2°C (32,36_F) between 0°C (32_F) and 70°C (158_F):
One is located in the left hand exit duct above a hole on the duct side. This hole
ensures that the thermistor is constantly in a moving air stream, regardless of
damper position.
The other one is located behind the air inlet, and measures the ambiant air
temperature.
Cooling system operational mode is solely dictated by the information provided by
the thermistor.
The nominal internal operating temperature (Ts) is set by switches (see Table 1–1)
located on the control board (see Figure 1–7).
The factory presetting temperature is 35°C (95_F).
Choice of nominal internal operating
temperature (Ts)
Blower speed
control
Nominal
internal
operating
Switch (SW1/1) Switch (SW1/2) Switch (SW1/3)
operating
temperature
(Ts)
OFF ON ON
(for full speed)
+35°C
(+ 95°F)
ON ON ON
(for full speed)
+25°C
(+ 77°F)
Table 1–1 Setting of nominal internal temperature
Cooling system operational mode is solely dictated by the information provided by
the thermistor.