LPS means Limited Power Sources. Please refer to IEC60950. There are two types, one is inherently Limited Power Sources, another non-inherently Limited Power Source. If former, its output current less than 8A/100VA. If latter, its current limits fuse shall no more than 5A.
In IEC60950 standard, it asks fire-free enclosure for IT products. However, if its power supply meets LPS and its electrical components insets on V1 (or better than V1) PCB, this product no needs the fire-free enclosure, that is, only HB grades one. HB grades enclosure is cheaper, better physics character, and also meets environmental requirements. That's why customer demand LPS for power supplies.
If any inquiries about LPS power supplies, please contact us firstname.lastname@example.org asap. Thank you.