Heatsink area size
Heatsink area size
(OP)
I have a circuit with four BTA312X triacs. The power three 1.1KWatt elements and one 2KWatt element. The Thermal Resistance is 1.15. The heater is powered from 240v mains and the circuit has an ambient of 65°C. How do I calculate the area of the heatsink required to keep the triacs cool? I want to use an extruded aluminium heatsink.





RE: Heatsink area size
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Heatsink area size
RE: Heatsink area size
Natural convection will probably get you to 1 or 2 BTU/hour/degF/ft^2. So at steady state, Q = h*A*dT. Once you choose the max allowable temperature, you can then find area.
EE
RE: Heatsink area size
You can get some decent back-of-the-napkin numbers without just a few minutes of calcs, but as the system gets more complicated (i.e., more cooling is needed), it becomes an engineering field unto itself.
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Heatsink area size
RE: Heatsink area size
TTFN

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RE: Heatsink area size
If ambient temperature Ta is 25C and accepted maxim capsule temperatue Tmax is for exampele 75C, it need that maxim thermal resistance (jonction to air) to be Rthmax =(Tmax-Ta) / Wt = 7.27 C/W and 4C/W. If Rth capsule-sink is 1.15, result maxim allowed Rth for sinks (6.12 and 2.85). From various technical guide must choose apropiate heatsink that have thermal resistance below these values.