Drawing is as follows: (which T3, T4, F22: electronic voltage transformer electrical graphic symbols)
Voltage transformer (Potential transformer abbreviated PT, Voltage transformer is also referred to as VT) and transformer is very similar, are used to change the voltage on the line. But the transformer transforms the voltage for the purpose of delivering power, so the capacity is very large, generally in kilovolt-ampere or megavolt-ampere as the unit of calculation; and voltage transformer transformer voltage is mainly used for the purpose of measuring instrumentation and relay protection device power supply, used to measure the line voltage, power and power, or used in the case of line failure to protect the line in the valuable equipment, motors and transformers, so the voltage transformer capacity is very small, generally are used to transform the line voltage, the power supply. The capacity of the transformer is very small, usually only a few volts amp, tens of volts amp, the maximum is not more than a thousand volts amp.
Voltage transformer is a transformer with iron core. It is mainly composed of primary and secondary coils, core and insulation. When a voltage U1 is applied to the primary winding, a magnetic flux φ is generated in the core, and according to the law of electromagnetic induction, a secondary voltage U2 is generated in the secondary winding.Changing the number of turns of the primary or secondary winding can produce different primary and secondary voltage ratios, which can be composed of different ratios of the voltage transformer. Voltage transformer will be converted to low voltage in proportion to the high voltage, that is, 100V, the primary side of the voltage transformer connected to the primary system, the secondary side of the measurement instruments, relay protection, etc.; mainly electromagnetic (capacitive voltage transformer is widely used), and there are non-electromagnetic, such as electronic, photoelectric type.