Overview
The JLS-35 is an outdoor oil-immersed three-phase combined instrument transformer rated for 35 kV systems. It integrates two single-phase voltage transformers (VTs) and two current transformers (CTs) within a sealed, oil-filled enclosure, providing reliable metering signals in harsh outdoor environments.
Designed for revenue-grade accuracy, it meets 0.2 / 0.2S classes for both voltage and current measurement. Typical applications include rural distribution networks, industrial facilities, and compact outdoor substations. The unit complies with GB 20840 series standards for combined instrument transformers, ensuring compatibility and performance in 50 Hz or 60 Hz systems.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| System voltage class | 35 kV |
| Rated frequency | 50 Hz / 60 Hz |
| Configuration | 2 × VT (V/V) + 2 × CT |
| Voltage transformer connection | V/V (open delta) |
| Current transformer phases | A and C |
| Accuracy class | 0.2 / 0.2S |
| Insulation type | Oil-immersed |
| Installation environment | Outdoor |
| Moisture protection | Enhanced barrier on tank cover |
| Applicable standards | GB 20840.4-2015, GB 20840.2-2014, GB 20840.3-2013 |
| Lightning protection | Surge arrester required within 1 m |
Model Designation
- J: Combined instrument transformer (voltage + current)
- L: Current transformer component designation
- S: Oil-immersed (liquid-insulated) construction
- 35: Voltage class (kV)
Construction
The JLS-35 features a compact rectangular oil tank constructed from high-quality steel with a weatherproof, corrosion-resistant coating. Inside, two fully-insulated single-phase voltage transformers and two electromagnetic current transformers—either toroidal or wound-core—are securely mounted on an internal frame. All components are immersed in high-quality transformer oil, which provides electrical insulation, thermal management, and environmental protection. The tank includes an enhanced moisture barrier on the cover to prevent humidity ingress, extending service life in outdoor conditions. External features include lifting lugs, an oil level sight glass, a grounding terminal, and an oil drain valve for maintenance. Secondary terminals exit through insulated bushings, with markings conforming to GB 20840 polarity and phasing standards.
Technical Parameters
Service Conditions
- Installation environment: Outdoor installation with direct weather exposure
- Altitude: Not exceeding 1000 m above sea level (higher altitude applications require engineering confirmation and possible derating)
- Ambient temperature: −25 °C to +40 °C (oil viscosity and insulation properties maintained across this range)
- Relative humidity: Daily average ≤ 95%, monthly average ≤ 90%
- Pollution level: Suitable for light to moderate pollution environments; heavy pollution areas may require enhanced external insulation
- Seismic conditions: Installations in seismic zones shall be confirmed during engineering design phase
- Environmental conditions: No corrosive gases or vapors that degrade oil or tank materials; no explosive atmosphere
Technical Parameters
The JLS-35 is a 35 kV class outdoor oil-immersed three-phase combined instrument transformer designed for metering in rural grids, substations, and industrial applications. It operates within an ambient temperature range of −25 °C to +40 °C and at altitudes up to 1000 m, featuring integrated voltage and current transformers with accuracy classes suitable for precision measurement. Primary current ratings span from 5 A to 1500 A with standard secondary outputs of 1 A or 5 A.
Voltage Transformer Data
| Rated Primary Voltage (kV) |
Rated Secondary Voltage (V) |
Accuracy Class |
Burden (VA) |
Connection Type |
|---|---|---|---|---|
| 35 / √3 | 100 / √3 | 0.2 / 0.2S | 25 – 100 VA (per core) | V/V (two single-phase units) |
| 35 / √3 | 100 | 0.2 / 0.2S | 25 – 100 VA (per core) | Line-to-neutral equivalent (V/V configuration) |
| Other voltage ratios available upon request and engineering confirmation | ||||
Current Transformer Data
| Rated Primary Current (A) |
Rated Secondary Current (A) |
Accuracy Class |
Burden (VA) |
Installation Location |
|---|---|---|---|---|
| 5 – 1500 A | 1 A / 5 A | 0.2 / 0.2S | 2.5 – 20 VA (per core) | Phases A and C |
| Specific ratio and burden combinations subject to engineering confirmation | ||||
Installation & Wiring
Outline Dimensions
The dimensional drawing provides overall tank dimensions, mounting hole locations, terminal positions, and accessory placement. Certified as-built drawings supplied with each unit shall be used for final installation layout.
Selection & FAQs
Selection Guide
- Select voltage transformer ratio based on system nominal voltage (typically 35 kV line-to-line) and required secondary voltage (e.g., 100 V or 100 / √3 V).
- Choose current transformer ratios that accommodate maximum load current with margin for overload and future load growth.
- Specify accuracy class as 0.2 or 0.2S depending on revenue metering needs—0.2S offers better performance at low load levels.
- Calculate total connected burden from meters, transducers, and wiring, then select a rated burden with sufficient safety margin.
- Verify that standard environmental ratings match installation conditions; request special configurations for high altitude, extreme temperatures, or heavy pollution.
- Confirm language preferences for nameplates and documentation if non-standard is required.
Frequently Asked Questions
Q1: Can this 35kV combined transformer be installed at altitudes above 1000 meters?
Yes, subject to engineering confirmation. Standard ratings apply up to 1000 m above sea level. For higher altitudes, derating or design modifications are required. Provide exact site elevation for factory assessment.
Q2: Which accuracy classes are available for the integrated voltage and current transformers?
Standard accuracy classes for precision measurement are provided, suitable for rural grids and substations. Specific class requirements for revenue billing must be specified during ordering. Confirm exact metering needs with our engineering team.
Q3: What pollution levels is this outdoor oil-immersed transformer designed for?
It is designed for light to moderate pollution levels. Heavy pollution areas require enhanced external insulation. Specify your site’s pollution severity during the inquiry phase for proper insulation coordination.
Q4: How are primary and secondary current ratings configured for the JLS-35?
Primary current ratings span from 5 A to 1500 A. Standard secondary outputs are available in 1 A or 5 A configurations. Specify your required primary and secondary current ratios for factory configuration.
Q5: When must seismic conditions be confirmed for substation installations?
Seismic requirements must be confirmed during the engineering design phase. Standard units assume normal seismic conditions. Provide your local seismic intensity parameters so we can verify structural adequacy before manufacturing.
Q6: Which factory tests are performed before shipping the 35kV transformer?
Standard routine tests are performed per applicable industry standards. Specific type tests or special customer requirements are subject to prior agreement. Request the detailed test schedule during the procurement phase.
Q7: Why choose a combined instrument transformer for rural grid metering?
It is primarily used for metering in 35 kV rural grids, substations, and industrial applications. The unit integrates both voltage and current transformation in a single outdoor oil-immersed tank.
Q8: Are there environmental restrictions for installing this 35kV transformer?
Yes, the installation environment must be free of corrosive gases, vapors, and explosive atmospheres. Ambient temperature must remain between −25 °C and +40 °C. Confirm site conditions with our technical team.