instrument transformer in which the secondary current, in normal conditions of use, is substantially proportional to the primary current and differs in phase from it by an angle which is approximately zero for an appropriate direction of the connections, trafo, mille sekundaarvool on tavapärastes kasutustingimustes oluliselt proportsionaalne primaarvooluga ja erineb sellest järk-järgult nurga all, mis on ühenduste sobiva suuna puhul ligikaudu null