Voltage transformer works

It works the same transformer, the basic structure is the core and the primary and secondary windings. Characterized by a constant and relatively small capacity, when normal operation is close to empty state. 
Impedance voltage transformer itself is small, once the secondary side short circuit, the current will increase Electric transformer and burned coils. To this end, the voltage transformer primary side is connected with fuses, the secondary grounded, so the primary and secondary side insulation is damaged, the secondary appeared high potential for ground personnel and equipment caused by accident. 
Measuring voltage transformers are generally made ​​of a single-phase double-coil structure, and its primary side voltage is measured voltage (such as the power system line voltage), you can use single-phase can also be used as a two-phase connected into VV-shaped be used. Laboratory Electric energy meter are often multi-tap of the primary side to accommodate the needs of different voltages measured. For protective grounding voltage transformer also comes with a third coil, said three coil voltage transformers. 
The third phase coils connected in open delta, the opening of the triangle two terminals and the ground voltage protection relay coil connection. 
Normal operation, the symmetrical three-phase voltage power system, the third coil of the three-phase induced electromotive force is zero. In the event of single-phase, the neutral point displacement occurs, open triangle will appear between the terminals so that the zero-sequence voltage relay, which play a protective role on the power system. 
The zero-sequence voltage coil Circuit breaker iron hearts will be zero-sequence flux. To this end, this three-phase voltage transformer yoke iron core using the next (10KV and below) or using three single-phase voltage transformer. For this transformer, the accuracy of the third coil less demanding, but requires a certain degree of over-excitation characteristics (ie, when the primary voltage is increased, the iron core is also a corresponding increase in the magnetic flux density in multiples without damage). 
Voltage transformers are power plants, substations and other transmission and distribution system is indispensable to a electrical appliances. 
Precision voltage transformer is used to electrically test laboratories to expand the range, the measured voltage, power and energy of an instrument. 
Voltage transformer and the transformer is very similar, are used to transform the voltage on the line.