JDJJ2-35/JDJJF2-35L 35kV Outdoor Oil-Immersed Voltage Transformer

Product Overview

The JDJJ2-35/JDJJF2-35L voltage transformer is an outdoor oil-immersed single-phase measurement device engineered for 35kV high-voltage power systems with enhanced anti-pollution performance. This advanced voltage transformer features oil-immersed insulation system that provides exceptional thermal dissipation for continuous high-load operation in harsh outdoor environments. The series includes two models: JDJJ2-35 for standard voltage transformation with 800VA thermal limit output, and JDJJF2-35L with residual voltage winding for ground fault detection and neutral point monitoring.

The JDJJ2-35/JDJJF2-35L delivers flexible voltage measurement solutions with multiple configurations: JDJJ2-35 (35/√3 : 0.1/√3 : 0.1/3kV) for standard voltage transformation, or JDJJF2-35L (35/√3 : 0.1/√3 : 0.1/√3 : 0.1/3kV) with residual voltage winding for ground fault detection. Multiple accuracy classes (0.2, 0.5, 1.0, 3P) accommodate precision metering to protection requirements, with thermal limit output up to 800VA (JDJJ2-35) or 600VA (JDJJF2-35L) 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. Wide operating temperature range (-40°C to +40°C) and compliance with GB20840.3-2013 and IEC61869-3:2011 standards ensure reliable performance across diverse applications.

Product Display

JDJJ2-35 voltage transformer

JDJJ2-35 voltage transformer application
JDJJ2-35 voltage transformer installation

Application Position

The JDJJ2-35/JDJJF2-35L 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. Typical installation includes concrete foundation mounting with proper grounding and clearance for maintenance access. The oil-immersed construction withstands harsh outdoor conditions including extreme temperatures (-40°C to +40°C), humidity, and pollution.

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 (JDJJF2-35L)
Applications with moderately to heavily polluted environments
High-burden applications requiring 800VA thermal limit output
Extreme temperature environments (-40°C to +40°C)

Application Case Studies

Application Scenario 1: High-Load Outdoor Substation Voltage Measurement
Utilities deploy JDJJ2-35 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 800VA thermal limit output ensures reliable performance even under heavy burden conditions in high ambient temperatures (+40°C). 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 JDJJF2-35L model with residual voltage winding (35/√3 : 0.1/√3 : 0.1/√3 : 0.1/3kV 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.

Application Fit

Suitable For

Outdoor 35kV voltage measurement applications
High thermal capacity requirements (800VA limit output)
Continuous heavy-load operation
Ground fault detection applications (JDJJF2-35L model)
Applications requiring superior thermal dissipation
High-voltage transmission and distribution networks
Industrial facilities with 35kV distribution systems
Extreme temperature environments (-40°C to +40°C)

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)
Applications requiring compact design (use epoxy cast-resin models)

Installation Conditions

Installation position: Outdoor substations, switching stations, or transmission networks
Ambient temperature: -40°C to +40°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)
Enclosure: Fully enclosed oil box (prevents oil aging)
Maintenance: Periodic oil testing and seal inspection required

Technical Parameters

The JDJJ2-35/JDJJF2-35L series includes outdoor oil-immersed single-phase voltage transformers for 35kV systems. Operating temperature -40°C to +40°C, compliant with GB20840.3-2013 and IEC61869-3:2011 standards.

Model	Rated Voltage Ratio (kV)	Accuracy Class & Rated Output (VA)	Thermal Limit Output (VA)	Insulation Level (kV)
JDJJ2-35 (Standard)	35/√3 : 0.1/√3 : 0.1/3	0.2/3P: 50/100 0.5/3P: 150/100 1.0/3P: 200/100	800	40.5/80/185
JDJJF2-35L (With residual winding)	35/√3 : 0.1/√3 : 0.1/√3 : 0.1/3	0.2/0.5/3P: 20/30/100	600	40.5/80/185

Note 1: JDJJ2-35 – Standard voltage transformation for metering and protection applications with 800VA thermal limit output.

Note 2: JDJJF2-35L – Includes residual voltage winding for ground fault detection and neutral point monitoring with 600VA thermal limit output.

Note 3: Rated output and its relative accuracy class only one alternative per transformer.

Note 4: If user’s data go beyond the above-mentioned scopes, they may be subject to an agreement between manufacturer and purchaser.

Installation

Dimension Reference

JDJJ2-35 voltage transformer dimension drawing
JDJJF2-35L voltage transformer dimension drawing

Overall dimensions vary by model. JDJJ2-35: Height 1055±5mm, Base width 435mm, Weight 103kg. JDJJF2-35L: Height 1055±5mm, Base width 435mm, Weight 110kg. Mounting: Installation size 400×250mm. Clearance: Minimum 600mm around transformer for maintenance access and oil sampling. Top terminals: High-voltage bushings with M10 studs. Secondary outlet: Bottom terminal box with 5-M10 (JDJJ2-35) or 7-M10 (JDJJF2-35L) terminals.

Wiring Diagram

JDJJ2-35 voltage transformer wiring diagram

JDJJ2-35/JDJJF2-35L supports multiple wiring configurations: Y/Δ connection (three windings) for standard voltage transformation and ground fault detection, or Y/Y/Δ connection (four windings) for comprehensive metering and protection. Primary terminals A, B, C connect to 35kV system. Secondary outputs a, b, c, n for metering and protection, da, dn for open-delta ground fault detection. Ensure proper polarity and phase sequence during installation.

Installation Guidelines

Foundation: Install on a level concrete foundation capable of supporting 103-110kg weight. Foundation should be 150mm above ground level to prevent water accumulation and facilitate oil sampling. Use anchor bolts secured into foundation with minimum 200mm embedment depth.
Grounding: Connect the grounding terminal (M10) 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.
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).
Primary Connection: Connect primary terminals (A, B, C) to the 35kV power system using appropriate high-voltage conductors or busbars. Ensure proper phase sequence and torque specifications.
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.
Oil Level Check: Before energizing, check the oil level indicator 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.
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 (800VA thermal limit output for JDJJ2-35, 600VA for JDJJF2-35L), 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 JDJJ2-35/JDJJF2-35L voltage transformer, consider the following factors:

Model Selection: Choose JDJJ2-35 for standard voltage measurement with 800VA thermal limit output, or JDJJF2-35L with residual voltage winding for ground fault detection
Accuracy Class: Choose 0.2 for revenue metering, 0.5 for monitoring applications, 1.0 for general measurement, 3P for protection applications
Burden Requirements: Ensure the rated output matches the connected load (metering devices, relays) to maintain accuracy. Thermal limit output is 800VA for JDJJ2-35 or 600VA for JDJJF2-35L
Environmental Conditions: Verify ambient temperature (-40°C to +40°C), altitude (≤1000m standard) 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 JDJJF2-35L 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 JDJJ2-35/JDJJF2-35L voltage transformer, please specify:

Model: JDJJ2-35 or JDJJF2-35L
Rated voltage ratio (e.g., 35/√3 : 0.1/√3 : 0.1/3kV)
Accuracy class and rated output (e.g., 0.2/3P-50/100VA)
Rated frequency (50Hz or 60Hz)
Quantity required
Any special requirements or custom specifications

FAQs

JDJJ2-35 is a standard voltage transformer with 35/√3 : 0.1/√3 : 0.1/3kV ratio for basic voltage measurement and 800VA thermal limit output. JDJJF2-35L includes a residual voltage winding with 35/√3 : 0.1/√3 : 0.1/√3 : 0.1/3kV ratio, providing ground fault detection capability through the open-delta secondary winding configuration with 600VA thermal limit output.

Oil-immersed transformers require periodic maintenance including oil quality testing (dielectric strength, moisture content, acidity), seal inspection for leaks, bushing inspection, and temperature monitoring. Recommended maintenance intervals are annually for critical applications or every 2-3 years for standard applications. The fully enclosed design reduces maintenance frequency compared to open-type transformers.

Oil-immersed insulation provides superior thermal dissipation, allowing higher thermal capacity (800VA limit output) and continuous operation under heavy burden conditions. The oil circulates naturally, transferring heat from core and windings to tank walls. Epoxy cast-resin transformers are maintenance-free but have lower thermal capacity and are better suited for space-constrained applications.

For revenue metering applications, accuracy class 0.2 is recommended to ensure precise energy measurement with 50VA rated output (0.2/3P-50/100VA). Class 0.5 (150VA) is suitable for monitoring and general measurement applications. Class 3P (100VA) is used for protection applications where accuracy is less critical than reliability during fault conditions.

With proper installation and regular maintenance, oil-immersed transformers have service life exceeding 30 years. Key factors affecting service life include operating temperature, load conditions, oil quality maintenance, and environmental factors. The fully enclosed design prevents oil aging, extending service life. Regular oil testing and maintenance ensure reliable operation throughout the equipment lifespan.

Standard ratios include 35/√3 : 0.1/√3 : 0.1/3kV and 35/√3 : 0.1/√3 : 0.1/√3 : 0.1/3kV. Custom ratios can be manufactured based on specific project requirements. Please contact our technical team for custom specifications and lead times. Custom ratios may affect accuracy class and rated output capabilities.

The JDJJ2-35/JDJJF2-35L complies with GB20840.3-2013 (Chinese standard) and IEC61869-3:2011 (international standard) for voltage transformers, ensuring compatibility with both domestic and international high-voltage measurement applications. The transformers are tested and certified according to these standards for accuracy, insulation, and thermal performance.

JDJJ2-35 weighs approximately 103kg, while JDJJF2-35L weighs approximately 110kg. The 7kg difference is due to the additional residual voltage winding and associated components in the JDJJF2-35L model. Both models have the same overall dimensions (height 1055±5mm, base width 435mm) and installation size (400×250mm).