4 • Control Link ACC I&O Manual 026-4704 Rev 6
4 Calculating Maximum Ambient
Temperature
Figure 4-1 shows the effects of adding an external heat sink with a 0.51°C/Watt (0.92°F/Watt) rating (using
thermal grease to ensure optimum thermal conductivity). Note that the 0.51°C/Watt
(0.92°F/Watt) heat sink rating is characteristic of typical case mullions.
An external heat sink is required for heater currents (greater than) > 10Amps.
To calculate the maximum ambient temperature at which the ACC should run with an additional external
heat sink, choose a current-amperage rating that will be operating for the case (y-axis) and plot the maximum
allowed operating temperature (x-axis) on the graph. For example, with an external heat sink at 26Amps, the
maximum ambient temperature would be 40°C (149°F).
For heater current greater than 10A, the heat sink of the Control Link ACC must be securely mounted
against a large heat-conductive surface. Using thermal grease, the Control Link ACC has a metal back which
acts as a heat sink, dissipating heat from the Triac that controls the heater. The metal must be mounted against
a conductive metal surface so heat can be conducted out of the controller. Failure to secure against the case
mullion or other metal surface may cause controller overheating and shutdown.
Figure 4-1 - Ambient Temperature Calculation - additional heat sink
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