LPS is the abbreviation for Limited Power Source.
In the IEC 60950 safety standard, the flame retardant case/enclosure is required for an IT product. When the main circuit of equipment is powered by LPS, it indicates that the voltage, current, and load are below the limits listed in IEC 60950-1 Table 2B; hence, a higher level of flame retardant case/enclosure for reducing the risk is not necessary. In other words, it is allowed to use the case/enclosure that is UL94 HB rated which offers a lower price, features improved physical properties, and meets environmental protection requirements more easily.