Partial discharges (or PD for short) are the small electrical sparks found within the insulation of medium to high voltage electrical systems. Partial discharges are caused by electrical breakdown and discontinuities within the insulation of an electrical system. Partial discharge testing is then done to help asset managers, technicians, and the companies they work for diagnose an electrical system and insulation before an unexpected outage occurs. Elektrorent carries partial discharge test units for both long and short-term rent.