What is High Voltage (HV)? Which Values ​​Are Considered High Voltage?

What is High Voltage? How Many Volts Does It Start From? High voltage (high voltage) refers to alternating voltages with an effective value above 1000 volts (1 kV). In international standards, levels above 1000 V AC and 1500 V DC are classified as high voltage and special insulation, equipment and safety rules apply for these voltages. In Turkey, the Electrical High Current Facilities Regulation is based on the same threshold, and in practice, line levels such as 34.5 kV, 154 kV, 380 kV are encountered in high voltage transmission and distribution systems. Briefly, the answer to the question "at what volt does high voltage start?" These are voltage levels above 1000 V where direct contact is extremely dangerous in terms of life safety. Therefore, the risk of electric field and arcing is taken into account even when approaching high voltage equipment.

LV, MV and HV Voltage Classes. Mains voltages in practice; They are divided into three main groups: low voltage (LV), medium voltage (MV) and high voltage (HV). LV generally refers to the 0–1000 V range and the 230/400 V level reaching the end user. MV covers network voltages between 1 and 36 kV and is used in cables and lines in urban areas and organized industrial zones. Levels of 36 kV and above are called HV; Transmission lines and large substations operate with these high voltage levels. In terms of legislation, all installations above 1 kV may be subject to high voltage installation provisions. For this reason, high voltage technique, safety rules and operation responsibility come into play in industrial facilities operating at MV levels such as 6 kV, 10 kV, 15 kV.

Why is High Voltage Necessary? Advantages of High Voltage. High voltage is used to transport electrical energy over long distances economically and efficiently. When the voltage is increased to transmit the same power over a line, the current (amperage) decreases; Thus, I²R losses in transmission and distribution lines decrease, conductor cross-sections become smaller and equipment costs are reduced. In this way, millions of kilowatts of electrical power can be safely transported from power plants to cities. High voltage technique; The voltage level is selected according to the power and distance carried by the line; It requires evaluation of insulation, short circuit resistance and safety limits together.

Where is High Voltage Used? High voltage facilities; It covers energy transmission lines, intercity MV/HV lines, transformer centers, switchyards, dam and power plant outlets, MV cubicles in large industrial facilities and high voltage motor drive systems. For field testing and maintenance of lines, cables and cells operating at these levels in Bursa and its surroundings Bursa HV/MV testing, maintenance and repair You need to benefit from their services. In industrial facilities, high voltage mostly occurs as the energy received from the MV network is converted into low voltage at the on-site substation. MV cubicles, breakers, separators, measurement transformers, power transformer and busbar systems work as a whole and the entire facility is managed according to the relevant HV operation responsibility procedures.

What is a High Voltage Line? High voltage line; It refers to overhead transmission and distribution lines with voltage levels of 34.5 kV and above, generally carried over insulators connected to steel cages or concrete poles. In these lines, conductors, insulator chains and line equipment carry both mechanical loads and provide sufficient electrical approach distance. A high voltage line creates an electric and magnetic field around it due to the electrical energy it carries. Therefore, when planning the line route, distances to settlements, buildings, roads and other infrastructures are determined according to regulations. Detailed distance calculation must be made in accordance with the relevant distribution company specifications and by authorized electrical engineers.

High Voltage Transformer and Transformer Substations. A high voltage transformer is a power transformer used to convert transmission or distribution voltage to higher or lower levels. For example, in 154/34.5 kV step-down substations, the energy at high voltage level is reduced to a lower MV level for city supplies. In transformer centers; breakers, separators, measurement transformers, surge arresters and busbar systems on the high voltage side; On the medium and low voltage side, there are cable outlets, MV cubicles and LV panels. For periodic testing and maintenance of these equipment transformer maintenance, testing and oil analysis with HV/MV maintenance and testing services should be planned together.

High Voltage Elements and Basic Components. In a high voltage facility; Many elements such as overhead line conductors, underground cables, insulators, poles and crossbars, busbar systems, breakers, separators, measurement transformers (current and voltage transformers), power transformers, surge arresters, capacitor banks and protection relays work together. Each high voltage element has a specific task to ensure both the electrical and mechanical safety of the system. Insulation distances, creepage lengths, grounding resistance and short circuit resistance are among the most critical design criteria of high voltage technology. These values ​​must be measured and recorded both during project design and operation.

Risks and Harms of High Voltage. High voltage poses a risk of electric shock, which can be fatal to the human body upon contact. If sufficient approach distance is not maintained, arcing through the air gap may occur even if there is no direct contact between the conductor and the body. Severe burns, equipment damage and fires may occur as a result of arcing. High voltage line damages include; Risks of electric shock due to improper distances, noise, corona discharge and electromagnetic field effects can be listed. Limit values ​​of these impacts and allowed approach distances are determined by legislation and taken into account during the project design phase.

Safe Working Rules in HV Facilities. Safe operation in high voltage facilities; It includes the steps of cutting off the power, applying lockout-tagout (LOTO), measuring and verifying voltage relief, and grounding the work area. The work area must be surrounded, limited with warning signs and only authorized personnel must be allowed in. The use of appropriate personal protective equipment (hard hat, insulating gloves, face shield, arc-resistant clothing, safety shoes, etc.) is an indispensable part of occupational safety at high voltage. These procedures are applied together with the instructions and directives prepared by the operational manager in the field.

What is High Voltage Operation Liability? In Turkey, high voltage operation responsibility in facilities above 1 kV must be undertaken by an electrical engineer authorized by the Chamber of Electrical Engineers (EMO). HV operation responsible engineer; It is responsible for the safe operation of substations and MV cubicles, performing periodic inspections and tests, keeping records and informing the personnel. For high voltage operation responsibility, transformer operation responsibility and substation operation services in industrial facilities in Bursa and its surroundings. SA operation responsibility and transformer operation responsibility You can review our pages and contact the Pow-Sys Power Systems team.

Result: Working Safely and Efficiently with High Voltage. In summary, high voltage; It refers to voltage levels whose effective value is above 1000 V and which require special insulation and safety measures. High voltage and high voltage levels are inevitable in order to transport electrical energy over long distances economically and with low loss; However, it is necessary to fully comply with the high voltage technique rules during the design, project planning and operation stages. For new HV/MV investments, substation projects, field tests and high voltage operation responsibility services LV/MV/HV project design and consultancy, Bursa HV/MV testing, maintenance and repair and Bursa transformer maintenance, testing and oil analysis You can benefit from our solutions.