Cabinet Venting

kolyur · Jan 31, 2020

I've used this online calculator in the past to size cabinet fans:

https://www.stego.co.uk/nc/services/calculation-tools/cooling-calculation/

Along the lines of what Tom mentioned, the "stray power" they ask for in the calculator is not the overall wattage of the components but rather the thermal dissipation, which should be provided in the datasheets.

rQx · Jan 31, 2020

Both Rittal and Allen Bradley have calculation software to dimension fans and AC. Rittal also have thermoelectric cooler/heater. In the AB software you can add their components and current draw and get the heat dissipation.

Gene Bond · Feb 1, 2020

Tom Jenkins said:
Be careful how you account for the heat with those solid-state relays. If 30A is the current passing through them the energy is not dissipated at the relay itself, but at the load they are controlling. If the load is outside your panel it isn't an issue for the panel temperature rise. The heat dissipated at the relay itself is only the heat generated by losses in the triacs. This is probably just a couple percent of the load current. The SSR data sheet should identify that.

Typically, I've used 1 volt drop per (controlled) phase, so 1 watt per phase per amp... This is on much larger loads, like solid state starters w/o bypass contactors.

talldude42 · Feb 3, 2020

The actual loads are heating elements located outside the cabinet. Thanks for the links to calculators. I will keep this info in mind for future projects!

Phil Buchanan · Feb 4, 2020

dirt pump (fan) on the bottom of one side and vent on top of opposite side. Pull in cool air from the bottom and let the heat rise and come out the top. Don't fight the laws of thermodynamics

Cabinet Venting

kolyur

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