Low ratio toroidal cts are in existence in many locations on power systems. The majority of these cts are in the auxiliary switchgear at generating stations, but are not limited to this application. The ratio of the cts used in this application is usually selected to accommodate metering and overload protection. The problem addressed here is the absence of consideration in this ratio selection for fault protection. In many cases the fault duty of this switchgear is very high and, because the low ratio cts also are of low accuracy classes, the cts will saturate during fault. Analysis of some fault cases shows that the protective relaying will not operate, or will not operate properly, due to the saturated cts