Powersem PSD 86/12 is an electrical system designed to ensure that an output voltage from a power supply can remain stable, regardless of the changing load current. This system works by monitoring the load current and adjusting the output voltage accordingly by controlling the resistance that is applied. The 86/12 part of the system indicates that the range of resistance used will have a minimum of 86 Ohms and a maximum of 12 Ohms. This means that the output voltage can be adjusted for different load current levels and still remain within the stable range.