JDX6-35kV Outdoor Oil-Immersed Voltage Transformer

Product Overview

The JDX6-35 voltage transformer is an outdoor oil-immersed single-phase measurement device engineered for 35kV high-voltage power systems with superior thermal performance. This advanced voltage transformer features oil-immersed insulation system that provides exceptional thermal dissipation for continuous high-load operation, making it ideal for applications requiring high thermal capacity. The JD(X)6-35 series includes two models: JD6-35 for basic voltage measurement and JDX6-35 with residual voltage winding for ground fault detection.

The JD(X)6-35 delivers flexible voltage measurement solutions with multiple configurations: JD6-35 (35000/100V) for standard voltage transformation, or JDX6-35 (35000/√3/100/√3/100/3V) with residual voltage winding for ground fault detection and neutral point monitoring. Multiple accuracy classes (0.2, 0.5, 1.0, 6P) accommodate precision metering to protection requirements, with thermal limit output up to 1000VA ensuring reliable performance under heavy burden conditions. The oil-immersed construction provides superior thermal dissipation compared to epoxy cast-resin alternatives, while the fully enclosed design prevents oil aging and extends service life. Anti-pollution grades W1 (Grade II) and W2 (Grade III) ensure reliable performance in moderately to heavily polluted environments. Wide operating temperature range (-5°C to +50°C) and compliance with GB20840.3-2013 and IEC61869-3:2011 standards ensure reliable performance across diverse applications.

Product Display

Application Position

The JD(X)6-35 is installed in outdoor substations, high-voltage switching stations, and transmission networks where reliable voltage measurement is required with superior thermal performance. The oil-immersed insulation system provides exceptional thermal dissipation for continuous high-load operation, making it ideal for applications where transformers operate near their thermal limits. The fully enclosed oil box construction prevents oil aging and extends service life, reducing maintenance requirements. Anti-pollution grades W1 (Grade II) and W2 (Grade III) ensure reliable performance in moderately to heavily polluted environments. Typical installation includes concrete foundation mounting with proper grounding and clearance for maintenance access. The oil-immersed construction withstands harsh outdoor conditions while providing superior thermal performance compared to dry-type alternatives.

Main Applications

• 35kV outdoor substations requiring high thermal capacity
• High-voltage transmission line voltage monitoring
• Industrial power distribution systems with continuous heavy loads
• Renewable energy substations (wind farms, solar plants)
• Rural electrification projects with outdoor distribution
• Utility networks requiring ground fault detection (JDX6-35)
• Applications with moderately to heavily polluted environments (W1/W2 grades)
• High-burden applications requiring 1000VA thermal limit output

Application Case Studies

Application Scenario 1: High-Load Outdoor Substation Voltage Measurement
Utilities deploy JD(X)6-35 oil-immersed voltage transformers in 35kV outdoor substations where continuous high-load operation requires superior thermal performance. The oil-immersed insulation system provides exceptional thermal dissipation, allowing the transformer to operate at higher burden levels without exceeding temperature limits. The 1000VA thermal limit output (JD6-35) or 2×500VA (JDX6-35) ensures reliable performance even under heavy burden conditions in high ambient temperatures (+50°C). The JDX6-35 model with residual voltage winding provides ground fault detection capability, enabling early detection of insulation faults and preventing equipment damage. The fully enclosed oil box construction prevents oil aging, extending service life and reducing maintenance requirements compared to open-type designs.

Application Scenario 2: Ground Fault Detection in Industrial Networks
Industrial facilities with 35kV distribution networks require reliable ground fault detection to prevent equipment damage and ensure personnel safety. The JDX6-35 model with residual voltage winding (35000/√3/100/√3/100/3V ratio) provides dedicated ground fault detection capability through the open-delta secondary winding configuration. The residual voltage winding detects zero-sequence voltage during ground faults, enabling protective relays to quickly isolate faulty sections and prevent cascading failures. The oil-immersed insulation system provides superior thermal performance for continuous operation, while the fully enclosed design prevents oil aging and extends service life. Anti-pollution grade W2 (Grade III) ensures reliable performance in industrial environments with moderate pollution, while the 100VA 6P accuracy class provides reliable protection performance during fault conditions.

Application Fit

Suitable For

• Outdoor 35kV voltage measurement applications
• High thermal capacity requirements (1000VA limit output)
• Continuous heavy-load operation
• Ground fault detection applications (JDX6-35 model)
• Moderately to heavily polluted environments (W1/W2 grades)
• Applications requiring superior thermal dissipation
• High-voltage transmission and distribution networks
• Industrial facilities with 35kV distribution systems

Not Recommended For

• Indoor installation applications (use indoor-rated models)
• Current measurement applications (use CT instead)
• High-voltage systems above 40.5kV (use higher voltage class models)
• Applications requiring maintenance-free operation (use epoxy cast-resin models)
• Space-constrained installations (oil-immersed transformers are larger)
• Extreme cold environments below -5°C (use special low-temperature models)

Installation Conditions

• Installation position: Outdoor substations, switching stations, or transmission networks
• Ambient temperature: -5°C to +50°C
• Altitude: ≤ 1000m (standard), higher altitude available on request
• Insulation: Oil-immersed (superior thermal dissipation)
• Frequency: 50Hz or 60Hz
• Phase configuration: Single-phase (use three units for three-phase systems)
• Anti-pollution grade: W1 (Grade II) or W2 (Grade III)
• Enclosure: Fully enclosed oil box (prevents oil aging)
• Maintenance: Periodic oil testing and seal inspection required

Technical Parameters

The JD(X)6-35 series includes outdoor oil-immersed single-phase voltage transformers for 35kV systems. Operating temperature -5°C to +50°C, compliant with GB20840.3-2013 and IEC61869-3:2011 standards.

Note 1: JD6-35 – Standard voltage transformation for metering and protection applications.

Note 2: JDX6-35 (single residual winding) – Includes residual voltage winding for ground fault detection and neutral point monitoring.

Note 3: JDX6-35 (dual residual winding) – Enhanced configuration with dual residual windings for redundant ground fault detection.

Note 4: Anti-pollution grades: W1 (Grade II) for moderate pollution, W2 (Grade III) for heavy pollution.

Note 5: Rated output and its relative accuracy class only one alternative per transformer.

Note 6: If user’s data go beyond the above-mentioned scopes, they may be subject to an agreement between manufacturer and purchaser.

Installation

Dimension Reference

Overall dimensions vary by model. Weight: approximately 69-85kg depending on configuration. Mounting: 4×M12 mounting bolts on base plate. Clearance: Minimum 600mm around transformer for maintenance access and oil sampling. Top terminals: High-voltage bushings with M16 studs. Secondary outlet: Bottom terminal box for cable connection.

Wiring Diagram

JD6-35: Primary terminals A, N connect to 35kV system. Secondary outputs a, n for metering and protection. JDX6-35: Primary terminals A, N connect to 35kV system. Secondary outputs a, n for metering, da, dn for open-delta ground fault detection. Ensure proper polarity and phase sequence during installation.

Installation Guidelines

1. Foundation: Install on a level concrete foundation capable of supporting 69-85kg weight. Foundation should be 150mm above ground level to prevent water accumulation and facilitate oil sampling. Use anchor bolts (M12) secured into foundation with minimum 200mm embedment depth.
2. Grounding: Connect the grounding terminal to the substation grounding grid using copper conductor with minimum 50mm² cross-section. Ensure grounding resistance is less than 4 ohms. Ground the transformer base and secondary winding neutral point.
3. Clearance: Maintain minimum 600mm clearance on all sides for maintenance access, oil sampling, and ventilation. Ensure adequate clearance from live parts according to local electrical codes (typically 400mm for 35kV).
4. Primary Connection: Connect primary terminals (A, N) to the 35kV power system using appropriate high-voltage conductors or busbars. Ensure proper phase sequence and torque specifications (typically 60 N·m for M16 bolts).
5. Secondary Connection: Connect secondary terminals to metering devices, protection relays, or monitoring equipment according to the wiring diagram. Use shielded cables for secondary circuits to minimize electromagnetic interference. Ensure proper termination and labeling.
6. Oil Level Check: Before energizing, check the oil level indicator (if equipped) to ensure proper oil level. The oil level should be between MIN and MAX marks. If oil level is low, contact manufacturer for oil filling procedure.
7. Commissioning Tests: Perform insulation resistance test (minimum 1000 MΩ at 20°C), turns ratio test, polarity test, and oil dielectric strength test (minimum 30kV/2.5mm) before energizing. Verify all connections are tight and properly torqued.

Oil-Immersed Insulation Features

• Superior Thermal Dissipation: Oil-immersed insulation provides exceptional thermal dissipation, allowing the transformer to operate at higher burden levels without exceeding temperature limits. The oil circulates naturally, transferring heat from the core and windings to the outer tank walls, where it is dissipated to the ambient air.
• High Thermal Capacity: The oil-immersed design provides high thermal capacity (1000VA thermal limit output), enabling continuous operation under heavy burden conditions. This is critical for applications where transformers operate near their thermal limits in high ambient temperatures.
• Fully Enclosed Construction: The fully enclosed oil box prevents oil aging by minimizing exposure to air and moisture. This extends oil service life and reduces maintenance requirements compared to open-type designs. The sealed construction also prevents contamination from dust and pollutants.
• Excellent Dielectric Strength: Transformer oil provides excellent dielectric strength, ensuring reliable insulation between windings and from windings to ground. The oil fills all voids and gaps in the insulation system, providing uniform electric field distribution and preventing partial discharge.
• Proven Technology: Oil-immersed transformers have been used for over a century in high-voltage applications, providing a proven track record of reliability and performance. The technology is well-understood, and maintenance procedures are standardized.

Standards

• GB20840.3-2013 (Instrument transformers – Part 3: Inductive voltage transformers)
• IEC61869-3:2011 (Instrument transformers – Part 3: Inductive voltage transformers)
• Customer-specific requirements available on request

Selection Guide

When selecting the JD(X)6-35 voltage transformer, consider the following factors:

• Model Selection: Choose JD6-35 for standard voltage measurement, or JDX6-35 with residual voltage winding for ground fault detection and neutral point monitoring
• Accuracy Class: Choose 0.2 for revenue metering, 0.5 for monitoring applications, 1.0 for general measurement, 6P for protection applications
• Burden Requirements: Ensure the rated output matches the connected load (metering devices, relays) to maintain accuracy. Thermal limit output is 1000VA for JD6-35 and single residual winding JDX6-35, or 2×500VA for dual residual winding JDX6-35
• Environmental Conditions: Verify ambient temperature (-5°C to +50°C), altitude (≤1000m standard), and anti-pollution grade (W1 for moderate, W2 for heavy pollution) match your installation environment
• Maintenance Capability: Oil-immersed transformers require periodic oil testing and seal inspection. Ensure this aligns with your maintenance strategy and resources
• Ground Fault Detection: If ground fault detection is required, select JDX6-35 model with residual voltage winding
• Thermal Performance: If superior thermal dissipation is required for continuous heavy-load operation, oil-immersed design provides better performance than epoxy cast-resin alternatives

Ordering Information

When ordering the JD(X)6-35 voltage transformer, please specify:

• Model: JD6-35 or JDX6-35 (specify single or dual residual winding if applicable)
• Rated voltage ratio (e.g., 35000/100V or 35000/√3/100/√3/100/3V)
• Accuracy class and rated output (e.g., 0.2/75VA, 0.5/150VA)
• Anti-pollution grade: W1 (Grade II) or W2 (Grade III)
• Rated frequency (50Hz or 60Hz)
• Quantity required
• Any special requirements or custom specifications

FAQs