4.4.4.17 Cooling system failure – B

4.4.4.17 Cooling system failure – Blanketing testIn addition to the applicable tests of subclause 4.4.4.8 of Part 1, inadvertent obstruction of the airflow over an exposed external heatsink shall be one of the fault conditions considered. No hazards according to the criteria of subclause 4.4.3 of Part 1 shall result from blanketing the inverter in accordance with the test below.This test is not required for inverters restricted to use only in closed electrical operating areas.NOTE The intent of this testing is to simulate unintentional blanketing that may occur after installation, due to lack of user awareness of the need for proper ventilation. For example, inverters for residential systems may be installed in spaces such as closets that originally allow proper ventilation, but later get used for storage of household goods. In such a situation, the heatsink may have materials resting against it that block convection and prevent heat exchange with the ambient air. Tests for blocked ventilation openings and failed fans are contained in Part 1, but not for blanketing of a heatsink.Compliance is checked by the following test, performed in accordance with the requirements of subclause 4.4.2 of Part 1 along with the following.