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Introduction
Not every outdoor metering point needs the same instrument transformer construction. In some projects an oil-immersed assembly remains the preferred choice, especially where that technology is already standard in the network. In others, a cast-resin combined instrument transformer is attractive because it can reduce maintenance concerns, avoid oil handling, and provide a cleaner compact structure for outdoor metering duty. That is where the JLSZY-35kV becomes especially relevant.
This model is best understood as a three-phase combined CT and VT assembly for outdoor measurement and protection work in the 35 kV class and in comparable international projects often described as 33 kV class. The decision to use it should be based on actual project conditions, not on a voltage label alone.
Why a Cast-Resin Combined Transformer May Be Preferred
The strongest reason to consider the JLSZY-35kV is usually not that it is simply another combined transformer, but that it uses a fully enclosed cast-resin outdoor structure. In projects where operators prefer to avoid oil-filled metering equipment, that construction can be easier to justify from a maintenance and environmental handling perspective. It may also be appealing where the site team wants a more self-contained assembly with less emphasis on oil inspection practice.
That does not mean cast resin is automatically the better answer in every network. The choice still depends on installation environment, maintenance philosophy, local standards, and how the asset owner evaluates long-term reliability. But when a resin-cast solution is preferred, the JLSZY-35kV fits that discussion naturally.
How the JLSZY-35kV Works in Outdoor Metering Schemes
The product combines CT and VT functions in one outdoor assembly. For metering projects, that can simplify the physical layout and reduce the number of separate primary devices that have to be mounted and wired in the field. The VT section uses a V/V arrangement, while the CT section is configured for practical metering duty through the selected phases. This kind of design is often useful where the project wants coordinated voltage and current measurement without building up the metering point from multiple standalone units.
Because the product combines both functions, the engineering review should treat the metering point as one complete system. Ratio selection, accuracy class, terminal planning, cable routing, and test access should all be checked together rather than handled in separate conversations.
What to Check for 33 kV and 35 kV Class Projects
1. Use the project voltage language correctly
In international work, the same general level of distribution or subtransmission equipment may be described as 33 kV, 35 kV, or in some markets 34.5 kV class depending on local utility practice. That wording should not be simplified too aggressively. A product named 35 kV by the manufacturer may still be considered in a 33 kV system if the approved insulation level, connection arrangement, and metering requirements are appropriate for the application.
The safest way to write that in a technical document is to describe the JLSZY-35kV as a solution for 35 kV class service and for comparable international outdoor metering projects such as 33 kV networks, subject to final project requirements and approved datasheet values.
2. Confirm whether the metering philosophy suits a combined assembly
Combined transformers are attractive where the metering point benefits from a coordinated package, but they are not always the ideal answer for every layout. Some sites may prefer separate CT and VT installations for maintenance or panel-routing reasons. The JLSZY-35kV becomes a stronger candidate when the project values compactness, reduced installation complexity, and a cleaner outdoor metering arrangement.
3. Review resin construction against the site environment
Cast-resin outdoor products are often selected because they offer a robust fully enclosed structure and avoid oil leakage concerns. Even so, the site conditions still need to be reviewed carefully. Pollution level, solar exposure, altitude, rainfall pattern, and long-term surface contamination all influence whether the selected insulation design is conservative enough for the project.
If the site is coastal, heavily polluted, or unusually elevated, those details should be reflected in the final review and not left as assumptions.
Why the V/V VT Arrangement Deserves Attention
The VT section is one of the most important parts of the specification because the V/V arrangement affects how the three-phase voltage measurement is derived. That is often efficient and practical, but it still needs to match the meter design, panel interface, and utility requirements. A product can look suitable from the outside while the secondary arrangement turns out to be awkward for the actual metering scheme.
For that reason, the better approach is to review the secondary voltage expectations, the intended meter type, and the wiring layout before finalizing the order. This is more reliable than assuming that any combined transformer with the right nominal voltage class will work the same way.
Where This Product Is Usually a Better Fit
The JLSZY-35kV is usually a better fit when the project wants outdoor metering and monitoring in one compact assembly, prefers resin-cast construction over oil-filled alternatives, and is working in a 33 kV or 35 kV class application where the final technical requirements line up with the product configuration. It is especially relevant where the owner values a cleaner maintenance profile and a more integrated outdoor measurement package.
It is less about claiming that one construction is universally superior and more about choosing the version that aligns with the site, the utility practice, and the life-cycle expectations of the installation.
Conclusion
The JLSZY-35kV should be chosen when the project needs a combined outdoor CT and VT assembly and has good reasons to prefer cast-resin construction over an oil-immersed alternative. For 33 kV and 35 kV metering projects, the stronger engineering path is to review the V/V voltage arrangement, current measurement duty, insulation environment, and site-specific operating conditions together before confirming the final specification.
Product Reference
For the base product configuration, source images, and original model details, refer to the JLSZY-35kV product page.