Voltage transformer reduces the high voltage to a certain extent. Its phase difference between the primary and seconder voltages is about zero. It provides that relay and measurement devices work at low voltage. Secondary side of the voltage measurement transformer ( v small ) is always balanced-to-ground. Earthing is compulsory in order to procure safety of life and property against the dangerous contact potential. Fuse is put on the primary and secondary side (protection to by-pass). It is certainly not put on the earthing line. As been in current transformers, in voltage transformers there are primary and secondary windings. Only difference is that primary windings are fine wire and multi-wind as for secondary windings are fine wire and less-wind. Primary tips are connected with circuit which will be measure its(U-V) voltage, secondary tips are connected the measurement device (u-v). Voltage transformers are manufactured as one and three phase.
