Short Circuit Current Measurements Between Transformer Sheets

In large transformer cores, burr-induced insulation faults between laminations can result in short-circuit currents which may be high enough to damage the core. This study presents measurements of the actual worst-case short circuit currents encountered in artificial interlamination shorts. A procedure using an adapted miniaturized Rogowski coil is described. Results show that the maximum short circuit current is not proportional to the core width, but, except for extremely narrow cores, it increases with good approximation linearly with the core width. Peak currents can in large cores reach several amperes even when only two laminations are involved.