What is the reason for high voltage lines having a larger diameter than low voltage lines?

Encyclopedia
10/04/2024

Analysis of reasons why the diameter of high voltage line is larger than that of low voltage line


The diameter of the high-voltage line is larger than that of the low-voltage line, mainly due to the following reasons:


Energy conservation and power matching


According to the law of conservation of energy, the transformer keeps the power constant while converting the voltage. Even at different voltage levels, the total power of input and output is the same 1. Since the higher the voltage, the smaller the current (according to the formula P = V * I, when the power is unchanged, the voltage is inversely proportional to the current), the current of the high-voltage line is smaller, and the diameter of the line can be naturally reduced. In contrast, low-voltage lines have a larger diameter because they need to transmit a larger current to meet the same power requirements.


Line loss consideration


The diameter of a line affects not only the ability to transmit current, but also the line loss. A wire with a larger wire diameter has a lower resistance, which reduces energy loss during transmission 2. Because the transmission distance of high-voltage transmission lines is long, the line loss is relatively small, so the line diameter can be appropriately reduced. Low voltage line due to the short distance, the line loss is relatively large, need a thicker line diameter to reduce energy loss.


Voltage classes and safety requirements


The voltage level of high-voltage lines is higher, usually used for long-distance transmission, and the insulation requirements for the wires are also higher. In order to ensure the safe operation of the line and prevent the influence of the electric field on the outside world, although the diameter of the high-voltage line is small, its insulation materials and structure may be more complex.


Mechanical strength and durability


Although the high voltage line current is small, considering the long-term operation and possible extreme weather conditions, such as wind and ice heavy, the line diameter of the high voltage line also needs to be sufficient mechanical strength to withstand these loads.6


In summary, the main reason why the diameter of the high-voltage line is larger than that of the low-voltage line is the current difference caused by the principle of conservation of energy, line loss control, safety and mechanical strength requirements. These factors together determine the different choice of line diameter in the design of high-voltage and low-voltage lines.


Encyclopedia

The Electricity Encyclopedia is dedicated to accelerating the dissemination and application of electricity knowledge and adding impetus to the development and innovation of the electricity industry.

What is Automatic Voltage Regulator?
What is Automatic Voltage Regulator?
An automatic voltage regulator is employed to regulate voltage, converting fluctuating voltages into a constant one. Voltage fluctuations mainly stem from variations in the load on the supply system. Such voltage variations can damage the equipment within the power system. These fluctuations can be mitigated by installing voltage - control equipment at various locations, such as near transformers, generators, and feeders. Multiple voltage regulators are often placed throughout the power system t
Edwiin
05/22/2025
What is Static Voltage Regulator?
What is Static Voltage Regulator?
Types of Static Voltage RegulatorThe static voltage regulator is superior to electromechanical regulators in respect of the accuracy of control, response, reliability and maintenance. The static voltage regulator is mainly classified into two types. They are;Servo Type Voltage RegulatorMagnetic Amplifier RegulatorThe types of static voltage regulator are described below in details;Servo Type Voltage RegulatorThe main feature of the servo type voltage regulator is the use of the amplidyne. The am
Edwiin
05/21/2025
What is Arc Extinction Circuit Breaker?
What is Arc Extinction Circuit Breaker?
When the current-carrying contacts of a circuit breaker separate, an arc forms and persists briefly after contact separation. This arc is hazardous due to the heat energy it generates, which can produce explosive forces.A circuit breaker must extinguish the arc without damaging equipment or endangering personnel. The arc significantly influences the breaker’s performance. Interrupting aDC arcis inherently more challenging than anAC arc. In an AC arc, the current naturally reaches zero duri
Edwiin
05/20/2025
Air Break Circuit Breaker
Air Break Circuit Breaker
In an air break circuit breaker, the arc is initiated and extinguished in substantially static air as the arc moves. These breakers are used for low voltages, generally up to 15 kV, with rupturing capacities of 500 MVA. As an arc-quenching medium, air circuit breakers offer several advantages over oil, including:Elimination of risks and maintenance associated with oil use.Absence of mechanical stress caused by gas pressure and oil movement.Elimination of costs from regular oil replacement due to
Edwiin
05/20/2025
Inquiry
Download
IEE-Business is dedicated to serving the personnel in the global power industry.
Join IEE-Business, not only can you discover power equipment and power knowledge, but also canhnd like - minded friends!