Overview
The LJWD-10/12 is an oil-immersed current transformer designed for 10 kV and 12 kV outdoor medium-voltage AC power systems. It features a steel-tank enclosure with mineral oil insulation, providing robust environmental protection and efficient thermal management through natural oil cooling.
Offering accuracy classes of 0.2 and 0.5 for metering and class 3/D for protection, it supports revenue-grade energy measurement and relay protection in distribution substations, industrial facilities, and SCADA-integrated grids. The design complies with GB 1208-1997 and IEC 61869-1/2 standards, ensuring reliable performance under continuous and fault conditions.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| System voltage class | 10 kV / 12 kV |
| Installation environment | Outdoor (indoor compatible) |
| Cooling method | Oil-immersed natural cooling |
| Rated frequency | 50 Hz (60 Hz optional) |
| Rated secondary current | 5 A |
| Accuracy classes | 0.2, 0.5 (metering); 3, D (protection) |
| Continuous thermal rating | 120% of rated primary current |
| Short-time thermal current (Ith) | Up to 30 kA (1 s) |
| Rated dynamic current (Idyn) | Up to 50 kA (peak) |
| Thermal stability coefficient | 187.5× rated primary current |
| Insulation system | Mineral oil with steel tank |
| Applicable standards | GB 1208-1997; IEC 61869-1 / IEC 61869-2 |
Construction
The LJWD-10/12 features a single-phase outdoor design with a welded steel-tank enclosure coated for weather resistance. Insulation is provided by mineral oil, enhanced by a diaphragm breathing system that isolates the oil from atmospheric air and moisture, reducing oxidation and preserving dielectric integrity over time. The core is constructed from ring-type silicon steel laminations optimized for low losses and high magnetic efficiency. Primary connections use bushing-type terminals (P1/P2), while secondary windings are accessible via standard terminal blocks (1S1/1S2 and 2S1/2S2 for dual-winding models). The unit employs vacuum oil-filling and impregnation processes to eliminate air bubbles, ensuring superior insulation strength and thermal performance. Natural oil circulation enables effective self-cooling, supporting continuous operation at elevated currents and high short-circuit withstand capability.
Technical Parameters
Service Conditions
- Installation environment: Indoor and outdoor installation (IP-rated enclosure)
- Altitude: Not exceeding 2000 m above sea level (4000 m capability available)
- Ambient temperature: −25 °C to +40 °C
- Relative humidity: ≤ 95% (no condensation)
- Pollution degree: Grade II (light to medium industrial pollution)
- Environmental conditions: Free from corrosive gases or vapors; free from explosive or flammable media; no severe vibration, mechanical shock, or impact
Technical Parameters
The LJWD-10/12 is an outdoor oil-immersed current transformer for 10–12 kV AC systems (50 Hz), featuring a steel tank and cast-resin insulation system. It operates within an ambient temperature range of −25 °C to +40 °C and up to 2000 m altitude (with options for 4000 m). Designed in compliance with relevant IEC standards, it supports primary current ratings from 5 A to 1500 A with multiple accuracy classes for metering and protection applications.
Current Transformer Data
| Rated Primary Current (A) |
Secondary Windings |
Accuracy Class |
Rated Output (VA) |
Short-Time Thermal Current |
Dynamic Current |
|---|---|---|---|---|---|
| 5 – 50 | 0.2/10P 0.2S/10P 0.5/10P |
0.2 / 0.5 / 3 / D | 5 – 15 | 15 kA | 37.5 kA |
| 75 – 100 | 5 – 20 | 20 kA | 50 kA | ||
| 150 – 300 | 10 – 30 | 25 kA | 62.5 kA | ||
| 400 – 600 | 15 – 30 | 30 kA | 75 kA | ||
| 800 – 1000 | 20 – 40 | 30 kA | |||
| 1200 – 1500 | 0.5 / 3 / D | 30 – 50 |
Installation & Wiring
Outline Dimensions
The outline dimensions and mounting details for the LJWD-10/12 oil-immersed current transformer are shown in the drawing above. The unit features a steel tank designed for outdoor installation, with designated fixing holes for secure mounting as per the provided installation drawings.
Wiring Diagram
The primary conductor connection is configured as a through-type busbar or bolted terminal, depending on system requirements. Secondary terminals are clearly marked (typically S1 and S2), with the S2 terminal designated for grounding in accordance with applicable standards. Ensure all secondary connections are tight and secure during installation and maintenance.
Selection & FAQs
Selection Guide
- Confirm the 10kV or 12kV system class, insulation requirements, frequency, and outdoor service conditions.
- Select the primary ratio from the maximum feeder current and protection study; confirm any dual-ratio requirement before ordering.
- Specify the accuracy class and rated VA separately for each metering or protection winding.
- Verify Ith and Idyn against the network fault level and protection clearing time.
- Confirm altitude, mounting dimensions, terminal arrangement, oil-handling requirements, grounding, and required test documents.
Frequently Asked Questions
Q1: Which accuracy class is best for revenue metering?
Select the 0.2S accuracy class for precise revenue billing. It maintains high accuracy across varying load conditions. Confirm specific rated output VA with our engineering team.
Q2: Can this oil-immersed CT be installed outdoors?
Yes, it features an IP-rated enclosure suitable for outdoor installation. Ensure the environment is free from corrosive gases and severe mechanical vibration. Verify IP rating details for your specific site.
Q3: What are the short-time thermal current ratings?
Short-time thermal and dynamic current ratings depend on the selected primary current rating. Refer to the detailed technical parameter table for exact values. Contact us for specific project calculations.
Q4: How is the altitude capability customized for high-altitude sites?
Standard models support up to 2000m, but 4000m capability is available. Specify your exact installation altitude during the inquiry phase. Factory confirmation is required for high-altitude configurations.
Q5: Are IEC compliance certificates provided with the order?
The transformer is designed in compliance with relevant IEC standards. Specific certificate availability and test reports are subject to confirmation. Please contact our sales team for documentation details.
Q6: Where is this 12kV current transformer typically applied?
It is designed for 10-12kV AC systems used in metering and protection applications. The steel tank and cast-resin insulation ensure reliable performance. Confirm your system frequency and voltage requirements.