Otis Singleton
In electrical engineering, EHV refers to voltages in the range of 345,000–765,000 V, though the definition depends on context. EHV is an acronym for extra-high voltage, which is used in power transmission from plants to load centres or between power grids. EHV is one of several voltage classifications, including high voltage (HV) and ultra-high voltage (UHV). The use of high and extra-high voltages in power transmission increases efficiency by allowing for thinner, lighter-weight cables, which reduces construction costs.
EHV-8 in electrical terms
| Characteristics | Values |
|---|---|
| Definition | Extra-high voltage |
| Range | 345,000–765,000 V |
| Context | Electrical power transmission engineering |
| Other Voltage Contexts | Voltages over 50V can cause dangerous amounts of current to flow through a human being |
| Voltages below 500-700V cannot produce easily visible sparks or glows in air at atmospheric pressure | |
| Voltages above 1000V for alternating current and 1500V for direct current are considered high voltage by the International Electrotechnical Commission | |
| High voltage ranges from 115,000 to 230,000 VAC | |
| Nominal voltage ranges from 35 kV to 220 kV |
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What You'll Learn
EHV is an abbreviation for extra-high voltage
In electronics systems, a power supply that provides greater than 275,000 volts is called an EHV Power Supply. This type of power supply is often used in physics experiments. The accelerating voltage for a television cathode ray tube may also be described as extra-high voltage or extra-high tension (EHT), compared to other voltage supplies within the equipment. This type of supply ranges from 5 kV to about 30 kV.
In the context of alternating current (AC) transmission voltage classes, EHV typically refers to a nominal voltage range of 330 kV to below 1000 kV. Internationally, this is the standard definition, though this range may vary by country. For example, in China, EHV AC networks refer to 330 kV, 500 kV, and 750 kV.
EHV transmission lines are significantly different from ultra-high voltage (UHV) transmission lines, with differences in overvoltage, key equipment, operation mode of the shunt reactor, requirements for relay protection, and impact on system operation. EHV transmission lines are very long, realising transregional and transbasin transmission.
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EHV voltage range
The definition of extra-high voltage (EHV) depends on context. In electric power transmission engineering, EHV is classified as voltages in the range of 345,000–765,000 V. In electronics systems, a power supply that provides greater than 275,000 volts is called an EHV Power Supply, and is often used in physics experiments.
In alternating current (AC) transmission voltage classes, EHV typically refers to a nominal voltage from 330 kV to below 1000 kV. In China, EHV AC networks refer to 330 kV, 500 kV, and 750 kV. Voltages higher than 765 kV are graded as ultra-high voltage (UHV).
The voltage level between 220 kV to 760 kV is also referred to as an extra-high voltage. Electrical variational analysis dictates that voltage and amperage are inversely proportional, meaning that when voltage is increased, amperage is decreased.
High voltage is defined by the International Electrotechnical Commission and its national counterparts (IET, IEEE, VDE, etc.) as above 1000 V for alternating current, and at least 1500 V for direct current. Voltages over approximately 50 volts can usually cause dangerous amounts of current to flow through a human being, so safety standards are more restrictive around such circuits.
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EHV power transmission
EHV or Extra High Voltage refers to voltages in the range of 345,000–765,000 V in electric power transmission engineering. In electronics systems, a power supply that provides greater than 275,000 volts is called an EHV Power Supply.
Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The voltage level is changed with transformers. The voltage is stepped up for transmission and then reduced for local distribution. This is done to reduce the losses produced by strong currents.
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EHV power supply
In electric power transmission engineering, EHV (extra-high voltage) is defined as voltages in the range of 345,000–765,000 V. In electronics systems, a power supply that provides greater than 275,000 volts is called an EHV Power Supply, and is often used in physics experiments.
Internationally, HV typically refers to a nominal voltage from 35 kV to 220 kV, EHV from 330 kV to below 1000 kV, and UHV 1000 kV and above. In China, HV AC networks refer to 110 kV and 220 kV, and EHV refers to 330 kV, 500 kV, and 750 kV. UHV AC transmission in China is 1000 kV AC.
EHV power transmission has some advantages and disadvantages when compared to UHV transmission. UHV transmission requires approximately two-thirds less land, which reduces the need for land resources and promotes sustainable development in the electric power industry. UHV transmission also has lower transmission losses and lower project costs than EHV transmission.
EHV Power is a North American company that provides high-voltage underground transmission cable services (69 to 345 kV) and is a leader in this field. They offer a wide range of products and services, including design, installation, and maintenance, for the high-voltage cable industry. EHV Power has a strong focus on health, safety, and environmental protection, maintaining high standards to mitigate and eliminate incidents and injuries.
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EHV line protection
Extra-high voltage (EHV) is defined as voltages in the range of 345,000–765,000 V in electric power transmission engineering. In electronics systems, a power supply that provides greater than 275,000 volts is called an EHV Power Supply.
EHV transmission lines require protection to ensure the safe transmission of electricity. The protection of EHV lines is a complex task due to the high-frequency harmonics involved, which affect the calculation accuracy of line protection. This challenge necessitates in-depth research and exploration of EHV line protection principles and reclosing techniques.
One novel protection scheme for EHV transmission lines is based on the conservation of travelling wave (TW) energy at the bus. When a fault TW reaches the bus, some energy propagates to other lines, while the rest is reflected back to the fault line. By introducing a directional energy conservation property, this scheme provides a criterion to identify whether the fault is within the protection zone. This approach has been demonstrated to quickly and reliably identify internal and external faults, unaffected by factors such as fault resistance and type.
Additionally, most EHV systems now employ two sets of protective relays for lines, buses, and transformers. These relays operate from separate potential and current transformers and station batteries, allowing for relay testing without disrupting the protected line or bus. Pilot-wire relaying is another technique, providing high-speed clearing of faults anywhere on the line.
Furthermore, substations serving EHV systems must provide a high order of reliability and security to ensure continuity of service. This has led to an increased emphasis on sophisticated relaying systems that can function reliably at high speeds while minimising false tripping.
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Frequently asked questions
EHV stands for Extra-High Voltage.
The voltage range for EHV is between 345,000 and 765,000 VAC. However, the range can vary depending on the context and region. For example, in electric power transmission engineering, EHV is classified as voltages between 345,000 and 765,000 V, while internationally, EHV refers to voltages from 330 kV to below 1000 kV.
EHV is higher than High Voltage (HV) and lower than Ultra-High Voltage (UHV). HV typically ranges from 35 kV to 220 kV, while UHV refers to voltages of 1000 kV and above.
EHV is used to increase efficiency in power transmission. By transmitting power at higher voltages, the accompanying current is lower, which allows for the use of thinner and lighter cables. This reduces the cost of tower and electrical line construction. EHV is often used for long-distance, large-capacity transmission to meet the electrical demands of industrial complexes and factories.
