A panel that passes its factory test at 22 °C can trip in August on a shop floor. Heat is a design input, not a site problem, and it has to be calculated before the enclosure is ordered.
Panels are designed around what goes in them and sized around what fits. The number that decides whether the design survives its first summer — the heat the components dissipate against the heat the enclosure can lose — is often calculated last, if at all. By then the enclosure is ordered, the layout is fixed, and the only remaining option is to bolt a cooling unit onto a door that was never planned for one.
The arithmetic is not difficult. Every device has a power loss figure in its datasheet: drives contribute the most, then power supplies, transformers, contactor coils, and the busbar and cable losses everyone forgets. Add them, compare against the enclosure’s specific heat dissipation at the ambient the panel will actually see, and the gap is the cooling capacity needed. What goes wrong is rarely the sum. It is the ambient.
Ambient temperature is where a specification quietly lies. "Indoor, 25 °C" describes an office, not a mezzanine above a furnace or a container in Anatolia in August. We ask for the temperature at the panel, at the worst hour of the worst month, and if nobody knows we write that into the quotation rather than pricing the optimistic case. A panel rated for 35 °C installed where it sees 45 °C has lost most of its margin before it is switched on.
The choice between filter fans, air-to-air exchangers and cooling units is decided by the environment, not by cost. Filter fans are cheapest and only work when the outside air is cooler and clean enough to let in; in a dusty or oily hall they become a maintenance debt and eventually a blocked panel. A closed-loop exchanger or a cooling unit keeps the ingress protection the rest of the specification promised. Choosing a fan to protect a budget and losing the enclosure’s IP54 is not a saving.
Layout carries as much of the load as the cooling device. Heat rises, so drives belong high and heat-sensitive electronics low, and air has to travel from the inlet across the components to the outlet without a wiring duct standing in the way. In a series family this counts twice, because the layout is drawn once and built forty times — an airflow mistake is not one hot panel, it is a fleet of them.
Ask for the heat calculation with the quotation, not after the first fault. It is one page: losses per device, the total, the ambient assumed, the enclosure’s dissipation, the cooling selected and the resulting internal temperature. A supplier who can hand it over has done the engineering. A supplier who offers to add a fan if it gets warm has quoted you a panel and left you the design risk.
— GANI Manufacturing engineering team