In the electric power system, the voltage division standard according to its security, transmission efficiency and application range is different. First of all, it is necessary to clarify that the power system does not have a clear concept of "medium voltage", is usually divided into five levels: extra-high voltage (greater than 500kV), high-voltage (1000V and above to 330kV or less), ultra-high voltage (330kV and above to 500kV and below), high-voltage (110kV. 220kV and 500kV), and low voltage (110kV. 220kV and 500kV), and low voltage, 220kV and 500kV), and low voltage (10kV and below, including 35kV and 20kV, but usually 20kV is regarded as the high voltage portion). 1000V is an important demarcation line to differentiate between high voltage and low voltage, and anything below this value is considered to be low voltage, and vice versa.
In the classification of AC voltages, below 1kV is considered low voltage, and 1kV to 20kV is called medium voltage, but this terminology is not common in actual power systems, and high voltage is usually used directly to describe this range. voltages above 20kV and up to 330kV are referred to as high-voltage, while those above 330kV are categorized as ultra-high voltage. Extra-high voltage, on the other hand, refers to AC voltages of 1,000kV and above, and is mainly used for long-distance transmission of large amounts of electricity to reduce energy losses during transmission.
Safety voltage standards state that AC should not exceed 36 V and DC should not exceed 50 V. High-voltage electricity, especially extra-high voltage, is highly hazardous, including high-voltage arcing electrocution and step-voltage electrocution, which can lead to fatal consequences. Therefore, extra care must be taken when touching and operating high voltage equipment.
In general, the voltage division of the power system is based on its characteristics in power transmission and use, and different voltage levels correspond to different safety standards and applications.