{"id":11964,"date":"2026-11-06T16:04:33","date_gmt":"2026-11-06T08:04:33","guid":{"rendered":"https:\/\/subian-electric.com\/?p=11964"},"modified":"2026-11-06T16:10:16","modified_gmt":"2026-11-06T08:10:16","slug":"what-is-a-medium-voltage-transformer","status":"publish","type":"post","link":"https:\/\/subian-electric.com\/ja\/blog\/what-is-a-medium-voltage-transformer\/","title":{"rendered":"What Is a Medium Voltage Transformer?"},"content":{"rendered":"<p>Medium voltage transformers are often associated as being between familiar and hidden devices, as it is easily seen on both ends of the spectrum, yet there are large amounts of people that do not normally associate a medium voltage transformer as being an electrical device. Consumers unfortunately purchase a medium voltage transformer thinking they are purchasing a larger version of a low voltage transformer when in fact they are purchasing a medium voltage transformer, and because of that mistake, many consumers do not purchase the correct medium voltage transformer.<\/p>\n<p>In this article, answers are provided for the questions that consumers are asking at this point: what are voltage lines? What types of devices are available? What is the optimal voltage class to be selected based on the system? How is a medium voltage system different from a low voltage system? What is a medium voltage transformer\u2019s price?<\/p>\n<blockquote><p>Medium voltage transformers are designed to convert the higher voltage Primary (E1) to medium voltage (E2) above 1 kV up to around 35 kV using many different types of electrical systems, such as Buildings, Industrial Plants or Utilities. According to IEC 60038, this range is classified as Medium Voltage Transformer, and the U.S. Department of Energy Regulations 10 CFR 431.192 classify a dry transformer in the Medium Voltage category as transformers between 601V and 34.5kV and those with ratings of 480 V and 600 V are considered to be in the Low Voltage category.<br \/>\nThe most commonly used ratings for this type of transformer are 11 kV, 13.8 kV, 20 kV, 22 kV, 33 kV and 34.5 kV.<\/p><\/blockquote>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-11966\" src=\"https:\/\/subian-electric.com\/wp-content\/uploads\/2026\/11\/What-Is-a-Medium-Voltage-Transformer.webp\" alt=\"What Is a Medium Voltage Transformer\" width=\"1448\" height=\"1086\" \/><\/p>\n<h2>Where Medium Voltage Starts, and Why the Line Moves by Country<\/h2>\n<p>The low-voltage classification as given in IEC 60038 includes all voltages below 1 kV and high voltages above it. Hence, voltages between 1 kV and 35 kV fall under the classification of medium voltage in most of Europe, Asia, Africa and Latin America. The principle behind this is that equipment exceeds a voltage level of 35 kV. At this voltage level insulation costs become the major costs and the equipment is constructed per each project instead of making it from common modules.<\/p>\n<p>Unlike other regions, America has not applied this clear distinction. In North America, the National Electric Code classifies high voltage systems as medium for wiring purposes when they exceed 600 V. Additionally, the regulation of Department of Energy states that medium voltage dry-type transformers should have voltage of 601 V and more. This is the main reason a widely-spread mistake occurs in international purchases when a buyer thinks that 600 V equipment is qualified because it is referred to as medium voltage on the schematics.<\/p>\n<table>\n<tbody>\n<tr>\n<th>\u53c2\u8003<\/th>\n<th>\u4f4e\u96fb\u5727<\/th>\n<th>\u4e2d\u96fb\u5727<\/th>\n<th>What it governs<\/th>\n<\/tr>\n<tr>\n<td>IEC 60038<\/td>\n<td>\u6700\u59271 kV<\/td>\n<td>1 kV to 35 kV<\/td>\n<td>Most of Europe, Asia, Africa, Latin America<\/td>\n<\/tr>\n<tr>\n<td>US DOE, 10 CFR 431.192<\/td>\n<td>Up to 600 V<\/td>\n<td>601 V to 34.5 kV<\/td>\n<td>Efficiency rule for dry type units sold in the US<\/td>\n<\/tr>\n<tr>\n<td>NEC Article 490<\/td>\n<td>Not applicable<\/td>\n<td>Over 600 V<\/td>\n<td>Clearance, grounding and protection requirements<\/td>\n<\/tr>\n<tr>\n<td>IEC 62271 families<\/td>\n<td>Not applicable<\/td>\n<td>1 kV to 52 kV common designs<\/td>\n<td>Which switchgear cubicle the unit can be cabled into<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>This entails two consequences; 600 V transformer is a low voltage product with a name that appears to denote something else, hence all its efficiency requirements, connection distances and switching apparatus are derived from low voltage standards. Also, 34.5 kV, the maximum voltage in US standards is not 35 kV which is the peak of IEC standard meaning that when the specifications are confused, coming up with device which meets the standards will be impossible.<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-11967\" src=\"https:\/\/subian-electric.com\/wp-content\/uploads\/2026\/11\/The-Five-Types-and-What-Each-One-Is-For.webp\" alt=\"The Five Types and What Each One Is For\" width=\"1448\" height=\"1086\" \/><\/p>\n<h2>The Types of Medium Voltage Transformer, by Construction<\/h2>\n<p>There are five different models of transformers available. Your decision for selection will be informed by the specifics of the site (where the transformer is placed), type of cooling, and whether maintenance is available. Different transformers have various specifications, and pricing is based on the size, design, temperature, and other parameters.<\/p>\n<ul>\n<li><span style=\"color: #000000;\">Concerning cast resin transformer design, the winding is covered with resin, which eliminates leaking and fire risks. T<\/span>hese transformers are commonly used indoors and are very well-rated in the USA. But the expense of casting and usage of resin makes this type of transformer unattractive for use in power-generating plants in terms of parameters and efficiency.<\/li>\n<li>Vacuum cast, or open wound design transformer is less expensive than the cast resin type and can be found in various production facilities. However, it is vulnerable to dust and water damage, and this requires its use in limited environments.<\/li>\n<li>Oil-immersed type of transformers is that done in the sealed tank, where mineral oil is used for cooling. Oil has better cooling properties than air, and, therefore, this type of transformer is more cost-effective. A <a href=\"https:\/\/subian-electric.com\/ja\/product\/20kv-oil-immersed-distribution-transformer\/\">20 kV oil immersed distribution transformer<\/a> is the standard answer for a pole or pad mounted unit feeding a housing estate or small industrial park. The trade is fire load, bunding, oil testing and the fact that the unit cannot go inside an occupied building without a fire-rated enclosure.<\/li>\n<li>Pad mounted. An oil unit equipped with a lockable enclosure, which is to be unfilled at grade along with accessible elbows and fuses without opening the tank. It is the utility standard in North America and is increasingly becoming common in Asia because it eliminates the necessity of having a secured substation.<\/li>\n<li>Unit substation. A transformer affixed to a medium voltage incoming section plus a low voltage distribution section that is delivered as a single unit. It reduces the use of cables, flooring space, and coordination requirements, and is the perfect solution when the load is situated in a single position and the building is new.<\/li>\n<\/ul>\n<p>There is a practical aspect of reading this list. If the unit is intended for indoor installation, it is classified as dry type only. If it goes outdoors and its capacity exceeds 500 kVA, it falls under oil type classification.<\/p>\n<h2>The Voltage Classes: 11 kV, 20 kV, 33 kV and Where Each One Belongs<\/h2>\n<p>The voltage class is a matter of the grid and not of the product, as it is settled by the utility long before the transformer is purchased. The purchaser has to know enough to read the drawing and comprehend that the quotation he receives is based on the wrong class instead of a cheap product.<\/p>\n<ul>\n<li>2.4 kV \u2013 6.9 kV. This voltage class was common in older industrial networks in North America as well as in some mining distribution networks and legacy plant networks. It is still applicable to certain refineries and paper mills where the switchgear is already in place and the cost of reconversion to another class is too high.<\/li>\n<li>11 kV. This voltage class is used globally, excluding North America, and is a norm in the UK, the Middle East, India, South-East Asia, Australia, and most of Africa. The majority of 11 kV transformers are designed for 11\/0.433 kV or 11\/0.415 kV power provision; they let a low voltage board work at 400 or 433 volts.<\/li>\n<li>13.8 kV and 12.47 kV. They are the North American equivalent of the above-mentioned class, used in utilities and industry. The standard commercial transformer in the USA is considered to be a 13.8 kV transformer with a voltage of 480Y\/277 V, which is different compared to 11 kV transformers even when the values of kVA correspond to each other.<\/li>\n<li>20 kV and 22 kV. These classes are applied all over continental Europe, China, Russia, and some parts of the Middle East. The 20 kV system can transmit more energy than 11 kV systems that is why it is often used in areas with dense urban distribution and industrial zones due to the load density that leads to the requirement for the higher insulation level.<\/li>\n<li>33 kV and 35 kV. Sub-transmission and large industrial distribution. A <a href=\"https:\/\/subian-electric.com\/ja\/33kv-voltage-transformer\/\">33 kV transformer<\/a> still sits inside the medium voltage family and is built from standard cores, coils and tanks, which is why its lead time is measured in weeks, not in quarters. Above 35 kV the market changes in kind, and a 132 kV unit is a project, not a product.<\/li>\n<\/ul>\n<p>The current rating represents the latter aspect of the two-part specification which is determined by load rather than voltage. A unit rated at 1000 kVA consuming power at a primary voltage of 11 kV draws about 52 A whereas a unit with the same rating working on a voltage of 33 kV draws only about 17.5 A. This adds up to the experiment that the primary cable, terminations and switchgear can be reduced in size when voltage increases and therefore the installation with a voltage of 33 kV with the same kVA can be cheaper in terms of cable and more expensive in insulation compared to an 11 kV installation.<\/p>\n<h2>How a Medium Voltage Transformer Differs from a Low Voltage One<\/h2>\n<p>The difference is not scale. It is standard, insulation, protection and test regime, and each of those changes the project.<\/p>\n<table>\n<tbody>\n<tr>\n<th>\u7279\u6027<\/th>\n<th>Low voltage transformer<\/th>\n<th>Medium voltage transformer<\/th>\n<\/tr>\n<tr>\n<td>\u4e3b\u96fb\u5727<\/td>\n<td>Up to 1 kV (600 V in US practice)<\/td>\n<td>1 kV to 35 kV<\/td>\n<\/tr>\n<tr>\n<td>\u6a19\u6e96<\/td>\n<td>IEC 60076-11 \/ UL 1561 \/ IEEE C57.12.01<\/td>\n<td>IEC 60076 series, IEEE C57.12.90 tests<\/td>\n<\/tr>\n<tr>\n<td>Insulation coordination<\/td>\n<td>Basic impulse level 10 kV or less<\/td>\n<td>BIL 60 to 200 kV depending on class<\/td>\n<\/tr>\n<tr>\n<td>\u4fdd\u8b77<\/td>\n<td>Moulded case breaker or fuse<\/td>\n<td>Relay, current transformers, MV switchgear, surge arresters<\/td>\n<\/tr>\n<tr>\n<td>\u7aef\u5b50<\/td>\n<td>Lug or busbar<\/td>\n<td>Stress cones, separable connectors, cable boxes<\/td>\n<\/tr>\n<tr>\n<td>Typical installation<\/td>\n<td>Electrical room, machine panel<\/td>\n<td>Substation, kiosk, compound, dedicated room<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Three practical implications. Due to being closer to the source, the secondary fault level is higher, which means that the low voltage board after it has a higher interrupting rating. Protection is a design-based not a choice-based process. The whole protection process comprises installation of current transformers, a relay having a curve, and coordination with the utility fuse. The implementation also requires people performing the work because if the stress cone on an 11 kV cable has been installed incorrectly, it will fail at the worst time and take the transformer down with it.<\/p>\n<p>The commercial comparison that is important is between medium voltage distribution and low voltage distribution over distance. Consider carrying 1 MVA at 400 V, which will require about 1,440 A and a cable of enormous size. Carrying the same 1 MVA at 11 kV requires only 52 A and the cable of incomparably smaller size. That\u2019s the essence of the whole medium voltage distribution logic, and that is the reason why in case of growth, industrial plants start adding medium voltage ring rather than another low voltage feeder to their distribution networks.<\/p>\n<p>The distinction that decides the product is which side of that boundary the unit sits on. A medium voltage unit is a different build, a different test regime and a different protection philosophy, and the <a href=\"https:\/\/subian-electric.com\/ja\/medium-voltage-dry-type-transformer-manufacturers\/\">range of medium voltage dry type transformers<\/a> is organised around the cast resin and open wound options described earlier, with enclosure, IP rating and temperature rise configured per order.<\/p>\n<h2>Where They Are Installed: Applications by Sector<\/h2>\n<p>The type of medium voltage transformer, the housing as well as the vector group are usually determined by the application. The next five sections include the main sectors of the medium voltage transformer market.<\/p>\n<ul>\n<li><span style=\"color: #ff0000;\">Commercial properties and computing centres.<\/span> The cast resin transformers are installed indoors and usually feature ratings of 11 kV or 13.8 kV down to 400\/230 V or 480Y\/277 V, with power ranging from 500 kVA to 2,500 kVA per transformer. The computing centres normally operate several transformers in parallel with the N+1 redundancy referring to a limitation in design requiring impedance matching.<\/li>\n<li><span style=\"color: #ff0000;\">Industrial plants.<\/span> The types of voltage transformers used can differ; that is why the applications of one may require oil immersed transformers while in another case cast resin transformers would be more suitable. The voltage transformers will usually be part of a colder ring of a steel mill of a cement manufacture, not a single large one, because the load is spread over the whole facility.<\/li>\n<li><span style=\"color: #ff0000;\">Power generation.<\/span> Wind mills and solar parks will use both pad mounted and skin mounted transformers stepping the voltage from 0.69 kV or 0.8 kV to 33 kV or 35 kV to collect power. Here the cyclic load and extended temperature range will play an important part in the characteristics of the transformer which normally has a very high load during the whole life.<\/li>\n<li><span style=\"color: #ff0000;\">Electrical distribution.<\/span> The pole and pad mounted transformers produce range of 25 kVA to 1,000 kVA to be used in village streets and smaller commercial areas. Such devices are very popular product, standardized, and are usually made according to an electric company specifications rather than project specifications.<\/li>\n<li><span style=\"color: #ff0000;\">Infrastructure and transport.<\/span> The construction of tunnels, underground railways, airports and sea and river ports. Here the fire protection class determines the type of the medium voltage transformer, and cast resin transformers are used almost always. However, the movement substations are a separate group of the medium voltage transformers as the distribution inside the tunnel is a traditional medium voltage transformer application.<\/li>\n<\/ul>\n<p>For projects that combine several of these, the supply is usually organised as a package, not as individual units, and a <a href=\"https:\/\/subian-electric.com\/ja\/medium-voltage-power-distribution-manufacturers\/\">medium voltage power distribution<\/a> scope will include the switchgear, the protection and the transformers together. That is worth doing when the site is new, because the interfaces between those three are where most commissioning problems live.<\/p>\n<h2>Sizing: kVA, Impedance and the Numbers on the Nameplate<\/h2>\n<p>The initial steps of sizing demand assessing the required load and determining four key numbers.<\/p>\n<p>Rated power refers to the power needed to sustain the load. The problem here is that one may use the nameplate values instead of assessing the load with diversity factor; this leads to overdesign and using the transformer at 30 percent of its capacity without any load losses.<\/p>\n<p>Impedance usually is in the range of 4.5% \u2013 8% for dry type transformers rated from 500 to 2500 kVA and is lower for its oil type counterparts. Impedance determines not only the fault current in the secondary circuit but also how the load is shared between the machines operating in parallel. If two transformers operate in parallel their impedances must be within 10% of each other; otherwise, the transformer with lower impedance will take more load, reach its rated value first, and will limit the operation of both machines.<\/p>\n<p>Temperature rise indicates the maximum temperature rise measured in degrees, which every dry type transformer may have. Having 150 degrees temperature rise transformer on the same feet frames can produce more kVA than 80 degrees transformer without the disadvantage of a shorter life. Class 220 insulation is used in almost all dry transformers now as it allows operation of a dry transformer with a rated rise of 115 degrees and a 150 degrees rated transformer.<\/p>\n<p>The last group of four letters describing the connection of the windings and the face shift between the windings. The most common connection is Dyn11 which means delta primary and star secondary with neutral connection and 30-degree phase shift between them. A <a href=\"https:\/\/subian-electric.com\/ja\/product\/10kv-dry-type-transformer-scbh-series\/\">10 kV dry type transformer in the SCBH series<\/a> is normally specified this way, with the enclosure, IP rating and temperature rise configured per order.<\/p>\n<p>It is important to be able to distinguish between a distribution transformer and a power transformer since they are priced and sized differently. A distribution transformer is designed to handle a load that changes during the day while a power transformer is designed for a constant load between two fixed locations. Thus, the assessment of losses and impedance values in these transformers is different.<\/p>\n<h2>What a Medium Voltage Transformer Costs in 2026<\/h2>\n<p>Price quotations are made ex works and depend on the conductor material, impedance, enclosure and testing regime. A European or American manufacturer will tend to quote prices that are 30%-50% higher than an Asian manufacturer at the same specifications, mainly because of differences in labor costs, certification costs, and documentation.<\/p>\n<table>\n<tbody>\n<tr>\n<th>\u5b9a\u683c\u3068\u30bf\u30a4\u30d7<\/th>\n<th>Typical price, ex works Asia<\/th>\n<th>What moves the number<\/th>\n<\/tr>\n<tr>\n<td>500 kVA cast resin, 11 kV \/ 0.4 kV<\/td>\n<td>$12,000 to $22,000<\/td>\n<td>Copper vs aluminium, IP rating, temperature rise<\/td>\n<\/tr>\n<tr>\n<td>1,000 kVA cast resin, 11 kV \/ 0.4 kV<\/td>\n<td>$18,000 to $45,000<\/td>\n<td>Impedance, class 220 insulation, enclosure<\/td>\n<\/tr>\n<tr>\n<td>1,000 kVA oil immersed, 33 kV \/ 0.4 kV<\/td>\n<td>$14,000 to $30,000<\/td>\n<td>Tank, conservator, tap changer, loss level<\/td>\n<\/tr>\n<tr>\n<td>2,500 kVA cast resin or oil<\/td>\n<td>$45,000 to $95,000<\/td>\n<td>Transport, enclosure, cooling class<\/td>\n<\/tr>\n<tr>\n<td>Pad mounted unit, 500 kVA, 13.8 kV<\/td>\n<td>$20,000 to $40,000<\/td>\n<td>Utility specification, elbows, fusing<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>The aspect which is surprising for the buyers regarding the installation, not the equipment itself. Medium voltage cable terminations, protection relays, current transformers, surge arresters, earthing as well as civil works for outdoor units can increase the cost of equipment by 40 to 80 percent for small projects, and the equipment cost can be exceeded for 500 kVA units supplying the small buildings.<\/p>\n<p>Losses are another factor which makes sense to count in the pricing. A typical 1,000 kVA unit consumes 1.2 \u2013 1.8 percent of its capacity in no-load losses, which means a significant cost for the electricity bill over the course of 8,760 hours. Losses can be reduced by paying additional 10 to 15 percent at the purchase price, and the investment can be paid off within four to seven years at industrial tariffs.<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-11968\" src=\"https:\/\/subian-electric.com\/wp-content\/uploads\/2026\/11\/What-It-Costs-and-Why-Two-Quotes-Differ-by-60-Percent.webp\" alt=\"What It Costs, and Why Two Quotes Differ by 60 Percent\" width=\"1448\" height=\"1086\" \/><\/p>\n<h2>Who Makes Them: Manufacturers Worth Shortlisting<\/h2>\n<p>The market is larger than that of the low voltage market as medium voltage transformers are manufactured regionally, and since the logistics concerning a 3-tonne device favour a supplier located within a radius of a few hundred kilometers.<\/p>\n<p>SGB-SMIT organisation is the largest independent transformer company in Europe with distribution and power transformer plants in Germany, the Netherlands, the Czech Republic, India, and the USA. Its main strength is the vast range of its transformers from small distribution transformers to big power transformers manufactured according to the IEC or IEEE standards.<\/p>\n<p>Ormazabal is the Spanish company producing medium voltage grid solutions as well as transformers including switchgear; transformers; substations that need to work together. Therefore, the integration of all equipment produced by the company creates an advantage for the project if one wants to keep only one contact for the medium voltage complex.<\/p>\n<p>Hitachi Energy and Siemens Energy produce the most developed transformers and operate in the market of electricity stations and supply through the type testing systems related to these markets. Both companies can be relied on while making an order for a 132kV transformer and during buying an 1000 kVA transformer.<\/p>\n<p>Hammond Power Solutions is the company specializing in dry type transformers in North America with the design data published and distribution network allowing the manufacture of a 500kVA cast resin transformer as its catalogue product. Being available in Canada and the USA, the product becomes more beneficial instead of the price.<\/p>\n<p>The majority of the capacity of the transformer market is produced by Chinese manufacturers and their exports in 2025 made \u00a564.6 billion, which is equal to a 36% increase compared to previous year\u2019s export. The ones known are holding IEC type test reports, UL or CSA certificates for the North American market, and a number of references in the country of delivery. The companies to avoid are those who provide certificates of 132kV transformers produced by the company with a history of producing only 10kV transformers.<\/p>\n<h2>Where SUBIAN Fits<\/h2>\n<p>Our production range spans between 10 kVA and around 20 MVA, with most of our deliveries falling under the kVA range between 30 and 2,500 at 10, 20, 33, and 35 kV, whether it be oil-immersed or cast resin transformers. Most of our delivery goes into distribution systems, production facilities, and other commercial buildings since their need is a ready-made product rather than customized ones.<\/p>\n<p>Three of our advantages in this regard are; we base our quotes on a single line diagram rather than on kVA figures, as parameters like vector group, impedance, and the tap range depend on the diagram; we provide a routine test report before shipment with test results on ratio, impedance, no load and load losses, and withstand voltage; we respond in a timely manner, informing the client from the first inquiry whether their project is beyond our operating parameters, as for us, it means over 35 kV.<\/p>\n<p>When talking about single-unit projects, it is worth mentioning that, for most commercial projects, our 10 kV and 20 kV dry and oil transformers are ideal. However, when medium voltage switchgear and protection are required, the subject of medium voltage distribution is preferable, as it deals with interactions of all components involved\u2013transformers, cubicles, and relays\u2013which are often the source of commissioning delays.<\/p>\n<h2>\u3088\u304f\u3042\u308b\u8cea\u554f<\/h2>\n<h3>Is 480V considered medium voltage?<\/h3>\n<p>According to both the IEC 60038, which defines the cut-off point at 1 kV, and the US DOE regulation regarding medium voltage transformers, which starts at 601 V, voltage levels of 480 V are classified as low voltage. 480 V is a low voltage distribution transformer, meaning that it must comply with low voltage efficiency requirements, meet low voltage clearance standards, and follow low voltage switchgear specifications. Indeed, the confusion arises from the fact that the feeder itself is described as medium voltage service and concerns the utility part of the substation rather than the transformer secondary.<\/p>\n<h3>Can I use AVR as a transformer?<\/h3>\n<p>The two devices have different purposes and functions. The automatic voltage regulator keeps the output voltage constant while the input and load changes. This is done by either changing the tap position or using a solid state regulator thus allowing the load to pass through. The transformer, on the other hand, changes the voltage through the defined ratio of the number of turns. While there is also an AVR that operates through the use of a transformer, the two devices do not serve the same purpose and the use of such terms freely results in some specifications that require certain performance of a nonregulative device.<\/p>\n<h3>What is the difference between CT and CVT?<\/h3>\n<p>The present-day transformers decrease the current flowing through electricity into a value of either 1 A or 5 A depending on the need for either protection or measurement. In operation, it does not allow supply to the output to become open circuit. Capacitive voltage transformers work on the principle of voltages splitting through capacitive dividers in the transformer\u2019s construction. Such type of voltage transformers is only appropriate for the use in the situation where it would not have been reasonable to use a magnetic transformer. Furthermore, compared to magnetic transformers, the CVT enables use of carrier frequency technology which allows communication on power line channels.<\/p>\n<h3>What are the three types of transformers?<\/h3>\n<p>The method of dividing transformers is commonly based on their function: step-up transformer, in which voltage is raised for transmission, step-down transformer, in which voltage is lowered for distribution or use, and isolating transformer, which transmits voltage with no change of the value of voltage and isolates two circuits in order to provide safety precautions and noise reduction. Another way of considering this classification is by design, i.e., whether the transformer is dry, oil immersed, or gas insulated where for medium voltage transformers this classification is more important than the first one.<\/p>\n<h2>\u53c2\u8003\u6587\u732e<\/h2>\n<ul>\n<li><a href=\"https:\/\/www.sgb-smit.com\/\" rel=\"nofollow noopener\" target=\"_blank\">SGB-SMIT Group \u2014 Distribution and Power Transformers<\/a><\/li>\n<li><a href=\"https:\/\/www.ormazabal.com\/\" rel=\"nofollow noopener\" target=\"_blank\">Ormazabal \u2014 Medium Voltage Networks and Substations<\/a><\/li>\n<li><a href=\"https:\/\/www.hammondpowersolutions.com\/\" rel=\"nofollow noopener\" target=\"_blank\">Hammond Power Solutions \u2014 Dry Type Transformer Design Data<\/a><\/li>\n<li><a href=\"https:\/\/www.hitachienergy.com\/\" rel=\"nofollow noopener\" target=\"_blank\">Hitachi Energy \u2014 Transformer Technology and Grid Applications<\/a><\/li>\n<li><a href=\"https:\/\/www.siemens-energy.com\/\" rel=\"nofollow noopener\" target=\"_blank\">Siemens Energy \u2014 Transformers and Medium Voltage Products<\/a><\/li>\n<\/ul>\n<h2>\u7d50\u8ad6<\/h2>\n<p>The IEC definition for medium voltage states that it starts from 1kV. In contrast, the US efficiency code defines 601V as medium voltage; this has become significant for many purchasers since equipment rated at 600V is; however, all low voltage equipment has a different designation (lower than \u201cmedium\u201d). When generating specifications, be sure to establish the maximum allowed voltage.<\/p>\n<p>Once this is done, determine what four key pieces of information will make it impossible to change them in the future: First, the maximum rated voltage class supplied by the utility company. Second, the appropriate vector group required by the line. Third, the measured impedance responsible for fault current and parallel behaviour (measured). Fourth, the maximum temperature rise above which the insulation\u2019s expected life would be shortened (approximately). The letter type and case type, as well as the manufacturer\u2019s name, will derive from these four pieces of information and you cannot fully specify a piece of equipment without referencing all four pieces of information.<\/p>\n<p>&nbsp;<\/p>","protected":false},"excerpt":{"rendered":"<p>Medium voltage transformers are often associated as being between familiar and hidden devices, as it is easily seen on both ends of the spectrum, yet there are large amounts of people that do not normally associate a medium voltage transformer as being an electrical device. Consumers unfortunately purchase a medium voltage transformer thinking they are purchasing a larger version of a low voltage transformer when in fact they are purchasing a medium voltage transformer, and because of that mistake, many consumers do not purchase the correct medium voltage transformer. In this article, answers are provided for the questions that consumers are asking at this point: what are voltage lines? What [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":11966,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-11964","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog"],"blocksy_meta":[],"acf":[],"_links":{"self":[{"href":"https:\/\/subian-electric.com\/ja\/wp-json\/wp\/v2\/posts\/11964","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/subian-electric.com\/ja\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/subian-electric.com\/ja\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/subian-electric.com\/ja\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/subian-electric.com\/ja\/wp-json\/wp\/v2\/comments?post=11964"}],"version-history":[{"count":7,"href":"https:\/\/subian-electric.com\/ja\/wp-json\/wp\/v2\/posts\/11964\/revisions"}],"predecessor-version":[{"id":11974,"href":"https:\/\/subian-electric.com\/ja\/wp-json\/wp\/v2\/posts\/11964\/revisions\/11974"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/subian-electric.com\/ja\/wp-json\/wp\/v2\/media\/11966"}],"wp:attachment":[{"href":"https:\/\/subian-electric.com\/ja\/wp-json\/wp\/v2\/media?parent=11964"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/subian-electric.com\/ja\/wp-json\/wp\/v2\/categories?post=11964"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/subian-electric.com\/ja\/wp-json\/wp\/v2\/tags?post=11964"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}