IEC 17.5kV switchgear Guzhou Weng will speak on electrical June 28, 2026 05:03 2 people

17.5kV is the IEC standard voltage level, applied in power systems with voltages of 13.2/13.8/15kV. IEC 17.5kV metal enclosed switchgear, rated voltage 17.5kV, power frequency withstand voltage 38kV, lightning impulse withstand voltage 95kV. Compact indoor installed switchgear in accordance with IEC 62271-1, 62271-200, and 62271-100.

More and more foreign projects require 17.5kV switchgear. 24kV switchgear is commonly used as a substitute in China, which is not only 40% larger in size than conventional 17.5kV switchgear abroad, but also 30% more expensive (of the same product grade and quality) than 17.5kV switchgear abroad, and cannot meet customers' requirements for space occupation and price.

The IEC62271-200 standard for metal enclosed switchgear defines the technical, parameter, and testing requirements of the switchgear. The IEC standard does not define the size of the switchgear, but has some basic definitions for the structure, such as loss of operational continuity (LSC), partition type PM/PI, internal arc fault level, etc. Therefore, there are many design schemes for the switchgear, which only need to meet the parameter performance requirements. That is, while meeting the parameter performance and passing the type test, the design can be freely developed without too many rules and regulations. The type and structure of the switchgear can be varied.

Secondly, it is important to know the typical overseas solutions, technical requirements, and application requirements, and select components accordingly.

The width of 17.5kV 1250A/31.5kA switchgear abroad is generally 650mm, with some 570mm wide such as Schneider MCSET-17, and many 600mm/620mm wide. For 2000A/40kA switchgear, the width is generally 750/800mm, which is relatively small and requires a very compact design of the switchgear.

The requirements for switchgear in foreign projects are more compact, making full use of all the space in the switchgear. Practicality, sturdiness, and reliability are key. For example, the incoming cable room of the switchgear requires current transformers, lightning arresters, grounding switches, voltage transformer handcarts, zero sequence current transformers, and connections of up to 8-10 cables per phase (3150-5000A high current). However, the depth of the switchgear is not large.

The problem that needs to be solved here is the interlocking of the incoming side grounding switch. Generally, mechanical interlocking is required for projects, that is, the grounding switch needs to be mechanically interlocked with the transformer and the upper level switch. There is also the issue of voltage transformer handcart. The space in the cable room is tight, and how to arrange the voltage transformer handcart, connect and pull it out, etc. all need to be solved.

Another safety requirement is that the anti internal arc level of the switchgear is necessary, usually 1 second, with very few requirements less than 1 second. For example, if the short-circuit current of the switchgear is 31.5kA, the anti internal arc level of the switchgear is IAC AFLR 31.5kA 1 second. Similarly, if the switchgear is 40kA, the IAC level is 40kA 1 second.

Therefore, for the design of domestic switchgear that generally lasts 0.5 seconds, it is necessary for the switchgear to be very strong, safe and sound from the outside in case of internal arc faults, and not cause any additional damage.

17.5kV switchgear is a widely used equipment in the medium voltage field abroad, which can cover voltage levels such as 3.6, 4.2, 7.2, 8.25, 11, 13.8kV in overseas IEC regions. Some Southeast Asian countries also require a surge withstand voltage of 95kV for 12kV switchgear, so 17.5kV switchgear can be used. In addition, for some overseas markets, IEC standard 11kV can also be applied at high altitudes of 2500 meters, without the need to use 24kV as a substitute. It is small in size, light in weight, and low in price.