Equipment carrying current will show a rise in temperature. Important during the test set up is to ensure that all factors which might have influence on the actual temperature rise are taken into account whether by real current or simulated by introducing power loss(heaters) sources equivalent to real equipment. Application of thermal Isolation to the sides of the panel represent the thermal transfer within a multiple panel system, heaters inside the panel may represent multiple outgoing units which have influence on critical “hot” spots.

Some heat producing devices within a panel require temperature measurements of its own. In this case a 15 kW variable frequency drive (VFD) is applied to control the load (e.g. motor units). The VFD requires additional cooling in order not to exceed the operational temperature of the VFD itself. A separate air cooling system is introduced for VFD.  This cooling system has also substantial  effect on the total temperature household of the system.

With the customer and certification body it was agreed to measure the effect of the VFD under normal operating conditions on the system. This required a set up in which actual load was applied to the VFD (resistor / capacitor banks). This means measurement of temperature rise on life parts. Instead of the use of normal thermal couplers, isolators were applied. The thermal couplers are connected to isolators which create a save galvanic separation of the dangerous voltages before being connected to the data loggers.

Once the temperature rises of the VFD in reference to air temperatures inside is known, one can predict the absolute temperature under higher internal ambient temperature due to other heat dissipating equipment.