Outdoor Current Transformer

The LB6-110kV capacitive outdoor current transformer is a core high-voltage supporting equipment from Zhejiang Yousen Electric. Specifically designed for complex outdoor operating conditions, it features a fully sealed oil-paper insulation oil-immersed structure, a rated operating voltage of 110kV, a maximum operating voltage of 126kV, and is compatible with 50Hz/60Hz AC power grids, meeting the operational requirements of neutral-point non-effectively grounded systems.

This product integrates measurement and protection functions, equipped with 0.2-class and 0.5-class metering windings and 5P/10P protection windings. It supports dual transformation ratios for series and parallel connection switching, with primary current coverage of 2×50A–2×1000A and secondary output of 1A/5A. Utilizing precision manufacturing processes in a reputable factory, the product boasts excellent environmental adaptability: the standard model is suitable for altitudes below 1000m, while the GYW high-altitude model can operate stably at 4000m altitude. It is widely used in urban and rural substations, industrial and mining power supply, and new energy power generation scenarios.

LB6-110kV Capacitive current transformer

Model Explanation and Usage Conditions

1. Model Parameter Explanation

The complete model number for the Outdoor Current Transformer is LB6-110kV P/P/P/0.5ab/c, divided into three core definitions:
- Basic Model: L indicates current transformer, B indicates with protection level, 6 indicates design serial number, 110 indicates rated voltage level, and W2 represents secondary anti-pollution configuration.
- Precision Combination: Built-in four sets of secondary windings, including one 0.5-class metering winding and three P-class protection windings, supporting various precision combinations to adapt to different metering and protection precision requirements.
- Current Ratio: Marked 2*a/c, supporting dual ratio switching. The ratio is a/c when the top oil conservator external connector is connected in series, and 2*a/c when connected in parallel. On-site wiring allows for easy switching.

2. Standard Operating Conditions

- Ambient Temperature: Maximum +40℃, Minimum -25℃, Daily Average Maximum +30℃; Ultra-low temperature conditions can be customized and negotiated.
- Installation Altitude: Standard type ≤1000m; LB6-110 GYW High Altitude type ≤4000m.

Product Structural Features

1.Winding and Insulation Structure

The primary winding adopts a U-shaped structure. Specifications of 2×400A and below use paper-insulated flat copper wire, while specifications of 2×500A–2×1000A use double-lobed semi-circular aluminum tubes. The core utilizes a capacitive oil-paper insulation process, with high-voltage cable paper wrapping the main insulation. Multiple layers of capacitor shielding create a uniform electric field, with the inner layer connected to high voltage and the outer layer grounded, significantly improving insulation safety. The primary winding is divided into two sections with four terminals, connecting to the top oil tank for easy ratio switching.

2.Sealed Protection Design

A metal expander is installed on the top to automatically compensate for changes in insulating oil volume caused by temperature variations, isolating air and preventing oil aging due to moisture, thus extending equipment lifespan. The expander has a built-in oil level observation window for real-time monitoring of the oil level. All secondary terminals and primary shielding terminals are centrally connected to the oil tank junction box, ensuring standardized wiring and strong anti-interference capabilities.

3.Safe Installation Structure

The oil tank is welded from high-quality steel plates, with pre-drilled lifting holes at the bottom for stable overall lifting. The junction box and oil tank are equipped with dedicated grounding bolts to ensure reliable grounding of the secondary winding and the entire unit. The product features a reduced polarity design; when primary current P1 enters and P2 exits, secondary current is output through S1/S2/S3, conforming to industry-standard wiring logic and facilitating on-site commissioning.

Core Technical Parameters

1. Basic Electrical Parameters

- Rated Operating Voltage: 110kV; Maximum Operating Voltage: 126kV
- Rated Frequency: 50/60Hz; Polarity: Subtractive Polarity
- Rated Primary Current: 2×50A～2×1000A (Multiple specifications available)
- Rated Secondary Current: 1A, 5A
- Secondary Output Capacity: 15VA～50VA (adaptive to transformer ratio)

2. Accuracy Error Standards

- Metering Class (0.2/0.5): Current error ±0.2%～±1.5%, phase difference 10′～90′, meeting high-precision energy metering requirements.
- Protection Class (5P/10P): 5P class current error ≤±1%, composite error ≤5%; 10P class composite error ≤10%, reliable protection operation in case of system fault.

3. Withstand Voltage and Insulation Parameters

- Power Frequency Withstand Voltage: 185kV/1min for primary and secondary circuits and to ground; 3kV/1min for secondary circuits and to ground; 5kV/1min for primary shield to ground. External insulation dry test: 230kV; wet test: 185kV.
- Lightning Impulse Withstand Voltage: Internal insulation 450kV; GYW2 high-altitude anti-pollution type up to 560kV.
- Creepage Distance: Standard type ≥16mm/kV; anti-pollution type up to ≥31mm/kV, suitable for harsh environments such as coastal areas, industrial pollution, and high altitudes.

4. Short Circuit Stability Parameters

The equipment exhibits excellent thermal and dynamic stability performance. For 300-600A specifications, the short-time thermal stability current can reach 31.5-45kA, and the dynamic stability current can reach 80-115kA, capable of withstanding instantaneous short-circuit current surges and preventing equipment damage.

Real-world Application Case

The Usune LB6-110kV Outdoor Current Transformer was successfully applied to a 110kV power grid substation upgrade project in East China, replacing outdated equipment and solving problems such as low accuracy, poor weather resistance, and frequent maintenance.

The project is located in a suburban industrial park, an area characterized by year-round humidity and slight industrial pollution, supplying power to multiple manufacturing companies. The project selected the LB6-110kV GYW anti-pollution high-altitude model (2×300/5A, 5P30/5P30/0.5S/0.2S accuracy combination). After more than two years of stable operation, the 0.2S/0.5S high-precision windings ensure accurate metering for industrial users, while multiple protection windings enable rapid response to grid fluctuations and minor short-circuit faults, achieving zero false trips and zero failures to trip. The fully sealed structure effectively resists moisture and contaminant corrosion, with no oil leakage or insulation aging issues, reducing subsequent maintenance workload by more than 60%, fully verifying the product's stability and reliability under harsh operating conditions.

LB 6 - 110 kV appearance and installation dimensions

Project Reference

Cas-space Rocket Launch Project

Test Report

FAQ

Q1: How to switch between dual current ratios on-site?

No equipment disassembly is required. Only the wiring configuration of the external connectors on the top oil conservator needs adjustment. Series connection of the primary windings is the base ratio a/c; parallel connection results in double the primary current ratio 2*a/c. The equipment is shipped in parallel by default; simply follow the wiring diagram for quick switching without affecting the equipment's insulation or lifespan.

Q2: Which scenarios are suitable for different insulation and anti-pollution models?

Standard type (≥16mm/kV) is suitable for plains areas with good environments below 1000m; W anti-pollution type (≥20mm/kV) is suitable for urban and general industrial pollution scenarios; GYW high-altitude anti-pollution type (≥25mm/kV) is suitable for high-altitude areas below 4000m; GYW2 enhanced type (≥31mm/kV) is designed for extreme conditions such as coastal salt spray, heavy industrial pollution, and ultra-high altitudes, offering stronger insulation anti-aging performance.

Q3: What are the core maintenance considerations for the Outdoor Current Transformer?

First, secondary open-circuit operation is strictly prohibited to avoid high-voltage induction risks. Second, the sealed structure must not be disassembled arbitrarily; maintenance-free operation is possible under normal conditions. Third, dielectric loss and insulation resistance should be tested annually, and the data must be basically consistent with the factory values. Fourth, oil levels should be checked seasonally, and qualified transformer oil should be added promptly when the oil level is low.

Product Advantages and Summary

The Usune LB6 series 110kV/126kV Outdoor Current Transformer, with its standardized design, stable performance, and strong environmental adaptability, solves the pain points of traditional equipment such as susceptibility to moisture, easy oil aging, and weak anti-fouling capabilities. Flexible ratio and accuracy combinations can meet the differentiated needs of power grid metering, relay protection, and industrial power monitoring. As a high-quality high-voltage equipment produced in a reputable Chinese factory, it provides highly reliable, cost-effective, and low-maintenance solutions for global power projects, making it a trustworthy supplier for power grid companies and engineering contractors.