The function and use of voltage transformer
The role of the voltage transformer is to convert the high voltage into a standard secondary voltage of 100V or lower in a proportional relationship for protection, measurement, and instrumentation. At the same time, the use of voltage transformers can isolate high voltages from electrical workers. Although the voltage transformer is also a device that works according to the principle of electromagnetic induction, its electromagnetic structure relationship is opposite to that of the current transformer. The secondary circuit of voltage transformer is a high impedance circuit, and the secondary current is determined by the impedance of the circuit. When the secondary load impedance decreases, the secondary current increases, making
The primary current automatically increases by one component to satisfy the electromagnetic balance between the primary and secondary sides. It can be said that the voltage transformer is a special transformer with limited structure and use form.
Voltage transformer is an indispensable electrical appliance in power plant, substation and other transmission and power supply systems.
Precision voltage transformer is a kind of instrument used to expand the limit and measure voltage, power and electric energy in the electric measurement laboratory.
Voltage transformers and transformers are very similar, both are used to change the voltage on the line. However, the purpose of the transformer conversion voltage is to transport electrical energy, so the capacity is very large, generally based on kilovolt-ampere or mega-volt-ampere as a unit of calculation; The purpose of voltage transformer voltage conversion is mainly to supply power to measuring instruments and relay protection devices, used to measure the voltage, power and electric energy of the line, or used to occur in the line
The barrier protects the valuable equipment, motors and transformers in the line, so the capacity of the voltage transformer is very small, generally only a few voltamps, tens of voltamps, and the maximum is not more than one thousand voltamps.
Why do you need to change the voltage on the line? This is because according to the different situations of power generation, transmission and electricity use, the voltage on the line is different, and the difference is wide, some low voltage 220V and 380V, some high voltage tens of thousands of volts or even hundreds of thousands of volts. To directly measure these low-voltage and high-voltage voltages, it is necessary to make the corresponding low-voltage and high-voltage voltmeters and other instruments according to the size of the line voltage
Appliances. This will not only bring great difficulties to the production of instruments, but more importantly, it is necessary to directly produce high-voltage instruments and measure voltage directly on the high-voltage line. That is impossible and absolutely not allowed.
If the voltage transformer is connected to the line to transform the voltage, then the low voltage and high voltage on the line can be uniformly converted into one or several low voltage voltages according to the corresponding proportion, as long as one or several voltage specifications of the instrument and relay, such as the universal voltage of 100V instrument, you can measure and monitor the voltage on the line through the voltage transformer.