Pollution Degree (PD) is an important classification for the clearance & creepage distances of electrical insulation, such as distance between components, PCB traces and power supply enclosure. With contaminants or condensation, the gaps are smaller increasing the risk of failure or short circuit. PD1 refers to environments with no pollution, or only dry non-conductive pollution such as sealed enclosures. PD2 are environments with only non-conductive pollution occasional temporary conductivity. Harsh industrial environments would fall under PD3 classification.

Both PMH-24V100WCAS and PMH-24V150WCBS models now includes pollution degree 3 classifications ensuring product reliability in industrial manufacturing environments. This applies to the new models PMH-24V100WCCS and PMH-24V150WCDS. They comply to pollution degree 3 even up to operating altitudes of 5000 meters.