What measures are employed to provide protection against ground faults on the load side of an UPS? I am in the UK and I have found that with mains healthy, earth loop impedance tests taken on the load side of the UPS often results in relatively high impedance values thus often rendering reliance for shock protection on mcbs alone less than adequate. However, I am also aware that there is ground fault protection built into the UPS which rapidly reduces voltage to the load in the event of a fault to earth. What I would like to know is just how this operates and can it be relied upon to provide appropriate shock protection or is it just designed to protect the UPS itself?

lyle dunn