HEIDENHAIN TNC 306 Technical Manual - Manual (Page 22)

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TNC 416/TNC 406/TNC 306 Installation 3–7
2.2 Heat generation and cooling
Please note that the reliability of electronic equipment is greatly reduced by continuous operation at
elevated temperatures. Please take the necessary measures to maintain the permissible ambient
temperature range.
Permissible ambient temperature during operation: 0 to 45° C (BF 110: 0 to 40° C)
The following means may be employed to ensure adequate heat removal:
– Provide sufficient space for air circulation.
– Build in a ventilator fan to circulate the air inside the control cabinet. The fan must reinforce the
natural convection. It must be mounted so that the warm air is extracted from the logic unit
and no pre-warmed air is blown into the unit. The warm air should flow over surfaces
that have good thermal conductivity to the external surroundings (e.g. sheet metal).
– For a closed steel housing without assisted cooling, the figure for heat conduction is 3 watt/m²
of surface per °C air temperature difference between inside and outside.
– Use a heat exchanger with separate internal and external circulation.
– Forced-air cooling by blowing external air through the control cabinet to replace the internal air. In
this case the ventilator fan must be mounted so that the warm air is extracted from the control
cabinet and only filtered air can be drawn in.
HEIDENHAIN advises against this method of
cooling , since the functioning and reliability of electronic assemblies are adversely affected by
contaminated air (fine dust, vapors, etc.). In addition to these disadvantages, an inadequately
serviced filter can lead to a loss in cooling efficiency. Regular servicing is therefore essential.
Obstructive
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Heat generating
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