Overview
The LJWD-10.12 Oil-Immersed High Voltage Current Transformer is a robust, single-phase instrument transformer designed for accurate current measurement, energy metering, and relay protection in 10kV and 12kV power systems operating at 50Hz. Housed in a sealed steel tank filled with insulating oil, it delivers reliable performance under continuous load up to 120% of rated current and is engineered for both indoor and outdoor installationsâeven in harsh environments with ambient temperatures from -25 deg C to +40 deg C and altitudes up to 4000m.
Built using advanced vacuum oil-filtration and oil-injection techniques, the LJWD-10.12 ensures superior dielectric strength and thermal stability. Its hermetically sealed design incorporates an internal diaphragm that isolates the oil from atmospheric air, significantly reducing oxidation and extending service life. Available with single or double secondary windings and multiple current ratios, this transformer offers flexible configuration options to meet diverse application requirements in distribution networks, substations, and industrial power systems.
Key Ratings Snapshot
| Parameter | Value |
|---|---|
| Rated Voltage | 10 kV / 12 kV |
| Primary Current Range | 5 A to 1500 A |
| Secondary Current | 5 A |
| Accuracy Classes | 0.2 (metering), 0.5 and 1.3(D) (protection) |
| Rated Secondary Burden | Up to 15 VA |
| Short-Time Thermal Current | Up to 30 kA (1s) |
| Dynamic Withstand Current | Up to 50 kA |
| Thermal Stability Factor | 187.5 x rated current |
Model Designation
The model code “LJWD-10.12” follows standardized Chinese nomenclature for current transformers:
- L: Current Transformer
- J: Steel Tank, Oil-Immersed Type
- W: Suitable for Indoor and Outdoor Use
- D: Double Secondary Winding (models without “D” have single winding)
- 10, 12: Rated System Voltage (10kV or 12kV)
Construction
The LJWD-10.12 features a self-cooling, oil-immersed design with a welded steel tank that provides excellent mechanical strength and environmental protection. The core is made of high-permeability grain-oriented silicon steel, ensuring low losses and high accuracy across the operating range. Advanced vacuum processing during manufacturing removes moisture and gases, enhancing insulation integrity and thermal performance.
The oil tank includes a sealed diaphragm system that prevents contact between transformer oil and ambient air, minimizing oxidation and moisture ingress. Primary terminals (P1, P2) are robust busbar-type connectors, while secondary terminals (S1, S2) are housed in a weatherproof terminal box with IP-rated cover suitable for outdoor exposure. Mounting is via standard base with bolt holes compliant with IEC 61869 clearance requirements.
Technical Parameters
Service Conditions
- Location: Indoor and outdoor use
- Ambient Temperature: -25 deg C to +40 deg C
- Relative Humidity: <=95%
- Altitude: <=4000m
- Pollution Level: Class II
Technical Data
| Model | Ratio | Accuracy | Burden (VA) | Thermal Current (kA) |
|---|---|---|---|---|
| LJWD-10.12 | 5/5 to 1500/5 | 0.2 / 0.5 / 1.3(D) | 10-15 (metering), 15-30 (protection) | 30 |
Installation & Wiring
Installation Diagram
The LJWD-10.12 is designed for pole or wall mounting using standard M12 bolts. Ensure minimum clearances per IEC 61869 for safe operation. Always connect secondary terminals to a burden or short-circuit before energizing the primary circuit.
Safety Notice: Never operate the transformer with the secondary winding open-circuited. This can induce hazardous overvoltages exceeding several kilovolts, posing serious risk of equipment damage and personal injury. Always short or load the secondary before applying primary voltage.
Selection & FAQs
Selection Guide
- Correct the taxonomy: LJWD-10.12 is a current transformer, not a voltage transformer, and should be moved out of the indoor voltage-transformer category.
- Select the current ratio: match the primary rating to maximum load and fault studies while retaining the specified 5A secondary.
- Choose core accuracy and burden: assign metering and protection cores separately and keep each connected burden within its VA rating.
- Verify short-circuit duty: confirm the stated 30kA thermal current together with rated duration, dynamic current and system fault level.
- Approve installation: confirm indoor/outdoor duty, oil sealing, 4000m claim, mounting, primary clearances, secondary earthing and shorting facilities.
Frequently Asked Questions
Q1: What are the outdoor installation limits for this oil-immersed current transformer?
It supports both indoor and outdoor use. The ambient temperature range is -25°C to +40°C with a maximum altitude of 4000m. Confirm specific site pollution levels with our engineering team.
Q2: How does this 12kV CT handle short-circuit fault currents?
The LJWD-10.12 withstands a rated thermal short-circuit current of 30 kA. This ensures reliable protection core performance during grid faults. Contact us to verify thermal limits for your specific network.
Q3: Which accuracy classes are available for metering and protection?
Metering cores offer 0.2 and 0.5 accuracy classes with 10-15 VA burden. Protection cores provide 1.3(D) class with 15-30 VA burden. Specify your exact ratio and burden requirements during ordering.
Q4: Can the current transformation ratio be customized for our project?
Yes, standard ratios range from 5/5 to 1500/5. Custom primary ratios are available subject to factory confirmation. Please provide your exact primary and secondary current requirements for a tailored quote.
Q5: What routine factory tests are performed before shipment?
Standard routine tests include ratio, polarity, and insulation resistance checks. Detailed test reports and specific type test certificates are subject to confirmation. Contact our sales team for the complete testing protocol.
Q6: Where is this 10.12kV oil-immersed CT typically applied?
It is designed for current measurement and protection in 10kV and 12kV power distribution systems. The oil-immersed design ensures high dielectric strength for switchgear applications. Request our application guide for more details.
Q7: How does high humidity affect this high voltage transformer?
The LJWD-10.12 operates reliably in relative humidity up to 95%. The oil-impregnated insulation prevents moisture ingress in severe environments. Verify environmental compliance with our technical support before final selection.