This section provides an overview for high voltage isolation transformers as well as their applications and principles. Also, please take a look at the list of 3 high voltage isolation transformer manufacturers and their company rankings. Here are the top-ranked high voltage isolation transformer companies as of December, 2023: 1.HIPOTRONICS, 2.Express Transformers & Controls Ltd..
A high-voltage isolation transformer is a device that protects precision electrical equipment and the human body from abnormal voltage caused by large current inflows (lightning surges) due to lightning strikes and power line accidents.
A lightning arrester (SPD) is also used to protect equipment from abnormal voltages. While surge arresters protect electrical equipment by discharging lightning surges to the ground, high voltage isolation transformers protect equipment from lightning surges by insulating it with a transformer while discharging lightning surges to the ground.
High-voltage isolation transformers are used in a variety of locations. The following are examples of applications.
High voltage isolation transformers are also installed between the power line and the protected equipment to protect the equipment from abnormal voltage.
There are two main types of high voltage isolation transformers: isolated and ground-separated, each with different principles.
In an isolated type high voltage isolation transformers, an abnormal voltage caused by lightning surges entering from the power supply side is released to the ground by a lightning arrester, while the voltage difference between the ground and the power supply is reduced by the isolation transformer.
The ground isolation type high voltage isolation transformers reduce the inflow of lightning surges between lines and between lines and ground with multiple surge arresters, and further protect the equipment by providing high insulation with an isolation transformer. The ground isolation type is also called a surge shelter.
In both cases, the protected device side is completely insulated against lightning surges by high voltage isolation transformers, and no lightning surges flow into the device. The high-voltage isolation transformers reduce the surge transfer rate from 1/100 to 1/10,000, which is more effective than the installation of surge arresters alone. In addition, the withstand voltage to abnormal voltage is extremely high at several tens of kilovolts, providing excellent protection.
High voltage isolation transformers and surge arresters are both devices used to protect equipment from lightning surges. However, there are structural differences between high-voltage isolation transformers and surge arresters.
A lightning arrester is connected in parallel with the device to be protected, and the arrester itself is grounded. Under normal conditions, the surge arrester acts as an insulator, but when surge voltages such as lightning occur, the surge arrester becomes conductive and releases the surge voltages to the ground. ZnO (zinc oxide) is often used as a material for surge arresters.
High voltage isolation transformers are similarly grounded by ZnO on the power supply side. However, high-voltage isolation transformers have a structure in which the primary and secondary sides are insulated by a transformer. Therefore, the limiting voltage can be significantly reduced. Due to the difference in the above structures, the high voltage isolation transformers are superior to the transformer against lightning surge.
High voltage isolation transformers are superior to lightning arresters in terms of lightning protection. However, there are three disadvantages as follows.
Transformers are inductive loads, so the reactive current increases. As a countermeasure, it is possible to connect power capacitors in parallel, but the cost will still increase. The grounding pole must be separate from the load. Most loads must be grounded to the chassis, etc., but high-voltage isolation transformers require an additional grounding pole for lightning surges. If the grounding pole for lightning surges and the load side grounding pole are combined, the potential between the load wire and the ground will also rise during lightning surges. Separating the grounding poles has the disadvantage of increasing the amount of grounding burial work and complicating the system. Based on the above merits and demerits, decide whether to use a lightning arrester or high voltage isolation transformers.
*Including some distributors, etc.
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Agile Magnetics, a part of Standex International (SXI) company, is a manufacturer of custom-designed electromagnetics located in Concord, New Hampshire. Its portfolio comprises high-frequency power assemblies, custom coils, and 50-60-400Hz products. They offer free design consultations to discuss customers' magnetic needs. The company is ISO 9001 and AS 9100 compliant, and its products can be meticulously tailored to meet the criteria of UL, CUL, VDE, CE, UL, and CUL, complete with the markings when required.
Hipotronics was established in 1962 and is a manufacturer of high-voltage test and measurement equipment in Brewster, New York. The company owns multiple brands, including AccelTex, Aclara, Hubbel, Worecon, and Delmar. It offers a product range that includes kilovoltmeters, hipot test equipment, AC dielectric test equipment, and DC test systems. Its electrical and electronic products are designed to be applicable for non-residential and residential construction, industrial and utility needs. They also provide OEM equipment and supplies, including isolation transformers, regulators, and DC supplies, to help original equipment manufacturers develop and deliver high-voltage products.