Two environmental obligations sit behind most medium voltage (MV) switchgear purchase orders, and neither of them appears on the nameplate. PCB restrictions govern what the insulation is made from. SF6 rules govern what is sealed inside the gas tank. A ring main unit (RMU) can carry every electrical certificate it needs and still fail a buyer's substance review if the material declaration and the gas-handling documents are missing.

This guide separates the two questions, then shows how the published construction data for the XGN15-12, XGN15-24, KYN28-12 and KYN28-24 assemblies from Changzhou Tuoxin Electric Co., Ltd. maps onto each one. Changzhou Tuoxin Electric Co., Ltd. is a switchgear manufacturer located in Xixiang Industrial Park, Hengshanqiao Town, Changzhou City, Jiangsu Province, China, founded in 2010, producing high-voltage switchgear, low-voltage switchgear, box-type substations, bus ducts, metering boxes and non-standard control cabinets.

Equipment commissioning site: the point at which gas pressure, ingress protection and the compliance file are checked against the order.

Why PCB and SF6 Are Two Different Compliance Questions

A PCB question is a materials question. Polychlorinated biphenyls are persistent organic pollutants that were historically used in electrical equipment such as capacitors and insulating fluids, and their manufacture and use have been restricted or eliminated in many jurisdictions. Compliance therefore depends on what the insulating components, impregnating media and any liquid-filled parts are made of.

An SF6 question is a containment question. Sulfur hexafluoride is a fluorinated greenhouse gas with a very high global warming potential, and many jurisdictions regulate its handling, reporting, recovery and destruction. Compliance depends on how much gas is sealed in, how fast it escapes, how pressure is monitored, and what happens to the gas at end of life.

The evidence is different, the reviewer is different, and the review timeline is different. A single safety certificate does not answer either question. Buyers who merge the two into one request usually receive a marketing statement instead of a compliance file.

Industry Background: Which Standard Governs What

Three separate layers apply to a medium voltage order, and it helps to name them correctly before requesting documents.

• Assembly standards. IEC 61439-1:2020 lays down general definitions, service conditions, construction requirements, technical characteristics and verification requirements for low-voltage switchgear and controlgear assemblies. For high-voltage and medium-voltage equipment, the IEC 62271 series covers high-voltage switchgear and controlgear, with part-level documents addressing specific equipment types, including AC metal-enclosed switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV.
• Substance regulation. PCB restrictions and SF6 obligations generally sit in national chemical, environmental or climate frameworks rather than in the assembly standard itself. That is why a unit can be fully type-tested and still be non-compliant with a buyer's environmental specification.
• Market access and certification. Conformity markings, management system certificates and type test reports are what allow a unit to be imported, installed and accepted on site.

The commercial backdrop explains why this is being reviewed more closely. Grand View Research estimates the global switchgear market at USD 119.7 billion in 2026, with a 7.4% CAGR projected to 2033, while the International Energy Agency forecasts global electricity demand growing at close to 4% through 2027. Growth of that kind puts more gas-insulated equipment into distribution networks, which in turn puts more attention on how SF6 inventories are documented. On the supply side, China was the top exporter of electrical control boards (HS 8537) in 2024 at USD 15.4 billion, according to the Observatory of Economic Complexity, so cross-border buyers routinely need to reconcile a supplier's domestic certification with the substance rules of the destination market.

PCB Compliance and Solid Insulation

The PCB question is far easier to close when the insulation is solid rather than liquid. On the XGN15-12, XGN15-24, KYN28-12 and KYN28-24 assemblies, the published material specification lists epoxy resin and SMC composite as the insulating components, together with rubber sealing parts and stainless steel fasteners. SMC is an unsaturated polyester glass-fibre composite. Neither material is a PCB-based insulating medium.

The same construction logic runs through the rest of the range. The MNS, GCS, GCK and GGD low-voltage switchgear specify SMC unsaturated polyester moulding compound, epoxy resin and PVC insulating sleeves for partition boards, busbar sleeves and support insulators. The YBW-12 prefabricated substation uses epoxy resin and SMC composite for bushings, supports and partitions. The DFW outdoor cable distribution box uses SMC composite and epoxy insulation board, with an SMC glass-fibre enclosure option for corrosive outdoor sites. For a buyer building a declaration file, that consistency matters: the insulating material class can be stated once and then confirmed per configuration.

Two details are easy to miss and both are worth raising with the supplier:

• Not every component in a package is solid-insulated. The YBW-12 prefabricated substation uses mineral transformer oil as the transformer cooling and insulating medium. Oil-filled equipment is exactly the category where PCB declarations matter most, so ask for a separate written statement for the transformer compartment rather than assuming the switchgear declaration covers it.
• Conductive and sealing materials belong in the declaration too. Busbars and contacts are T2 pure copper with tin or silver plating, sealing elements are nitrile rubber and silicone rubber rings, and fasteners are stainless steel. A materials declaration that names them is more useful than a one-line certificate of conformity.

The practical question to put to a manufacturer is not "is your switchgear PCB-free?" but "which components in this ordered configuration could carry a liquid or impregnated insulating medium, and what is declared for each one?" That phrasing forces a component-level answer.

ISO 14001 certificate 76426E00039R001, issued by DaHua Certification Services Co., Ltd., valid 8 April 2026 to 7 April 2029, covering manufacture of high-voltage switchgear, box-type substations and low-voltage switchgear within the scope of CCC.

SF6 Compliance and the Sealed Gas System

In the XGN15-12 and XGN15-24 ring main units, sulfur hexafluoride serves as the arc-extinguishing and insulating medium. Everything an SF6 reviewer needs is therefore in the construction data, and the numbers are specific rather than qualitative.

On the XGN15-24 gas-insulated metal-enclosed RMU, the gas is held in a fully welded 304 stainless steel gas tank. The rated filling pressure is 0.04–0.06 MPa (gauge, at 20 °C) and the minimum operating pressure is 0.02 MPa. The specified annual gas leakage rate is ≤0.5%. Sealing elements are nitrile rubber and silicone rubber rings selected to avoid gas leakage. The tank interior is rated IP67 and the cabinet exterior IP34D. The XGN15-12 SF6 ring main unit follows the same principle, with a sealed gas tank made of stainless steel plate and SF6 as its arc-extinguishing and insulating medium.

Three points turn those figures into a usable compliance argument:

• A leakage rate is a maintenance commitment, not a marketing claim. A stated ≤0.5% per year allows the buyer to calculate gas top-up intervals and to set a re-test schedule instead of discovering a low-pressure condition at the next inspection.
• Pressure thresholds define the operating limit. The gap between the 0.04–0.06 MPa filling range and the 0.02 MPa minimum operating pressure is the working window, and it should be written into the operating instructions handed to the site team.
• Mechanical life affects sealing integrity. The XGN15-24 load switch is rated for ≥5,000 mechanical operations and the earthing switch for ≥2,000. Operation counts that exceed the sealing's design life are a maintenance risk, not only a wear risk.

The service envelope is part of the same argument. XGN15-24 is rated for ambient temperatures from −25 °C to +40 °C, altitudes up to 2,000 m with a customised version required above that, daily average relative humidity ≤95% and monthly average ≤90%, and indoor installation free of flammable, explosive and corrosive gases. An SF6 enclosure installed outside its declared envelope is a compliance exposure even if the gas system itself is sound.

End of life deserves a question of its own. Since the gas must be recovered rather than vented, ask which party takes responsibility for recovery, what documentation accompanies decommissioning, and whether the answer changes for an export project where local recovery infrastructure may not exist.

Ingress Protection and the Access-Control Side of Compliance

Substance compliance rarely travels alone. Reviewers also check that people cannot reach live parts, and ingress protection ratings are the fastest way to verify it. On the KYN28-12 indoor metal-clad withdrawable switchgear, the enclosure is rated IP4X and the rating is IP2X with the circuit breaker door open. In plain terms, IP4X excludes solid objects larger than 1 mm and makes no water-ingress claim, while IP2X is the finger-safe level. The KYN28-24 metal-clad withdrawable switchgear is rated IP4X.

The same ratings appear across the low-voltage and auxiliary equipment that usually ships with an MV package: IP30 on the MNS, GCS, GCK and GGD low-voltage switchgear and on the PZ30 distribution box, IP30 on the VFD control cabinet with the frequency converter main unit at IP20, IP30 indoors or IP44 outdoors on the XL AC and ATS distribution boxes, and IP54, IP44 or IP34D on the DFW outdoor cable distribution box. Where a project needs a higher grade, protection can be upgraded to IP30, IP40, IP54 or IP65 with a customised fully sealed outdoor structure.

Building the Compliance File: A Step-by-Step Breakdown

1. Define the question before requesting documents. Write two separate lines in the RFQ: one for substance declarations covering insulating components and any liquid-filled parts, one for gas containment data covering filling pressure, minimum operating pressure, annual leakage rate and recovery arrangements. A combined request produces a combined answer that satisfies neither reviewer.
2. Classify each item by insulation medium. Separate the SF6 ring main units (XGN15-12, XGN15-24) from the solid-insulated metal-clad assemblies (KYN28-12, KYN28-24) and from any oil-filled equipment in the package (the YBW-12 transformer compartment). The declaration set differs for each group.
3. Request a component-level material declaration. Insulating components should be named as epoxy resin and SMC composite, with the conductive parts identified as T2 pure copper with tin or silver plating and the sealing parts as rubber, nitrile or silicone as applicable. Reject declarations that name only the finished assembly.
4. Verify the gas figures against the operating instructions. Filling pressure 0.04–0.06 MPa, minimum operating pressure 0.02 MPa, annual leakage ≤0.5%, and the tank material stated as fully welded 304 stainless steel. If those numbers do not appear in the manual, the manual is incomplete.
5. Check protection ratings in both states. Confirm the enclosure rating and the open-door rating separately, for example IP4X with IP2X at the circuit breaker door on KYN28-12, or IP67 inside the gas tank with IP34D outside the XGN15-24 cabinet.
6. Match the certificate scope to the product actually ordered. A management system certificate is only relevant if its scope covers the product family. The ISO 9001, ISO 14001 and ISO 45001 certificates held by Changzhou Tuoxin Electric Co., Ltd. cover manufacture of high-voltage switchgear, box-type substations and low-voltage switchgear within the scope of CCC, and each certificate number and validity date can be checked against the issuing body.
7. Agree the lifecycle terms in writing. Mechanical operation counts, gas top-up responsibility, sealing replacement intervals, recovery at decommissioning, and the ambient and altitude limits of the installation.

ISO 9001 certificate 76426Q00092R001: the scope statement is what ties a management system certificate to the specific product family being purchased.

Certification held by the manufacturer

Changzhou Tuoxin Electric Co., Ltd. holds CNAS-accredited ISO 9001, ISO 14001 and ISO 45001 certificates issued by DaHua Certification Services Co., Ltd. — 76426Q00092R001 under GB/T19001-2016/ISO9001:2015, 76426E00039R001 under GB/T24001-2016/ISO14001:2015 and 76426S00037R001 under GB/T45001-2020/ISO45001:2018 — all valid from 8 April 2026 to 7 April 2029 and all scoped to the manufacture of high-voltage switchgear, box-type substations and low-voltage switchgear within the scope of CCC. Complete switchgear and low-voltage products also hold CCC certification from the China Quality Certification Centre, and the company states that products are backed by full type test reports. Those certificates have been used on supply to major power and energy end users including State Grid, China Southern Power Grid and new energy enterprises.

Use Cases: Where Each Configuration Fits a Compliance Position

Urban ring networks at 12 kV. The XGN15-12 SF6 ring main unit is built for indoor distribution systems at 50 Hz and 12 kV, and is used in industrial and civil cable ring networks and supply terminal applications — small secondary substations, switching stations, industrial and mining enterprises, urban residential communities, airports, railways, tunnels and high-rise buildings. Its compliance position is a contained SF6 system with a stainless steel sealed tank and solid epoxy/SMC insulation.

24 kV compact distribution. The XGN15-24 gas-insulated RMU is used in urban grid construction and renovation, ring main supply and terminal distribution, and can be installed in prefabricated substations and switching stations. It is fully enclosed and maintenance-free, which is attractive in constrained urban sites and also concentrates the SF6 documentation requirement into a single, well-specified unit.

Projects that restrict gas-insulated equipment. Where a specification favours solid insulation, the KYN28-12 and KYN28-24 metal-clad withdrawable assemblies are the relevant alternatives in the range. KYN28-12 covers three-phase AC 50 Hz systems at 3–12 kV with single busbar and single busbar sectionalised arrangements, at 630–4000 A and 20–50 kA breaking current. KYN28-24 covers 24 kV at 50/60 Hz, 630–3150 A, and is used in power plants, substations, industrial and mining enterprises and high-rise buildings.

Packaged substations. The YBW-12 prefabricated substation combines high-voltage and low-voltage sides at 12 kV, with 50–1600 kVA capacity, IP3X on the high-voltage side and IP2X in the transformer compartment. It is the case where the PCB declaration must extend to the transformer oil, and where the two-axis compliance review is genuinely necessary.

Export tenders. With an export ratio of 40% and markets including Vietnam, Indonesia, Morocco, Ivory Coast, Cameroon, Tanzania, Kenya, Russia, Kazakhstan, Uzbekistan, Mexico, Colombia, Chile, Peru, Spain, Brazil, Portugal, Turkey, Croatia, Germany, Italy, Austria, Switzerland, Saudi Arabia, the UAE, Qatar, Kuwait, Oman, Japan, South Korea, the USA and Canada, the documentation package has to satisfy more than one regulatory interpretation. Bilingual documents are part of that requirement rather than a courtesy.

Comparison Table: Insulation and Gas Data by Model

Table sources: published product material and parameter data for each model. Entries marked as not stated are not claimed rather than assumed.

Frequently Asked Questions

Conclusion

PCB and SF6 compliance are answered by two different sets of documents, and the equipment data already contains most of what an evaluator needs. On the material side, the insulating components across the KYN28-12, KYN28-24, XGN15-12, XGN15-24 and YBW-12 designs are epoxy resin and SMC composite rather than a PCB-based medium, with the transformer oil in the YBW-12 handled as a separate liquid declaration. On the gas side, the XGN15-24 specifies a fully welded 304 stainless steel tank, a filling pressure of 0.04–0.06 MPa, a minimum operating pressure of 0.02 MPa and an annual leakage rate of ≤0.5%, with IP67 inside the tank and IP34D outside the cabinet.

The gap that most often slows an approval is not product performance but documentation. A buyer who receives the component-level declaration, the gas figures, both ingress protection states and verifiable certificate numbers can close the review without a second round of questions.

Request the compliance documentation package

Changzhou Tuoxin Electric Co., Ltd. supplies the material declaration, ISO 9001/14001/45001 certificate copies, CCC documentation and model-level parameter sheets together with a quotation for the ordered configuration. Minimum order quantity 1 unit, lead time 30–45 days, 100% tested before dispatch.

ISO 45001 certificate 76426S00037R001, valid 8 April 2026 to 7 April 2029.

Email: sale@tuoxinelectric.com  |  Tel: +86 181-3691-5112  |  WhatsApp: +86 158-6188-2821
Website: www.tuoxinelectric.com  |  Address: Xixiang Industrial Park, Hengshanqiao Town, Changzhou City, Jiangsu Province, P.R. China