110 kV Current Transformer

The Usune LB6-110 kV Current Transformer is an outdoor high-precision current sensing device adapted to medium- and high-voltage power grids. It adopts a modular structure and a multi-group secondary winding design. The wiring method can be adjusted via external connecting plates in the top oil conservator, enabling flexible switching between dual current ratios to meet the current detection and fault protection needs of different operating conditions.

This product complies with GB/T20840.2-2014 national standard and IEC international electrotechnical standards. It includes standard, high-altitude, and pollution-resistant models, offering excellent measurement and protection accuracy. Suitable for both conventional and harsh outdoor conditions, it is a mainstream supporting equipment for domestic 110kV power transmission and distribution systems.

LB6-110kV Capacitive current transformer

Model Explanation and Applicable Operating Conditions

1. Model Code Meaning

The complete product model is LB6-110kV (accuracy combination + current ratio), with clear and standardized segmented explanations:
- Basic Model: L for current transformer, B for with protection level, 6 for design serial number, 110 for rated voltage 110kV, W2 for secondary anti-pollution design
- Accuracy Class Combination: Supports multiple winding combinations such as P/P/P/0.5 and P/P/0.2, including 0.2/0.5 level metering windings and 5P/10P level protection windings, balancing high-precision metering and reliable fault protection.
- Current Ratio Specification: Marked as 2*a/c, supports dual current ratio switching, series connection is a/c, parallel connection is 2*a/c, primary current covers 2×50A~2×1000A, secondary current is 1A/5A full specification

2. Applicable Operating Conditions

- Ambient Temperature: Suitable for operating conditions from -25℃ to +40℃, with a daily maximum temperature of +30℃. Ultra-low temperature requirements can be customized and negotiated.
- Altitude: Standard model suitable for altitudes ≤1000m; GYW high-altitude model suitable for altitudes ≤4000m.
- Environmental Adaptability: Creepage distance selectable from 16mm/KV to 31mm/KV, suitable for various scenarios including conventional, coastal corrosion protection, and high-altitude anti-fouling applications.

Core Structural Features

1.Optimized Insulation System

Employs capacitive oil-paper insulation technology, with high-voltage cable paper wrapping the primary winding core. It features a multi-layered capacitor shielding layer, with the inner layer connected to high voltage and the outer layer grounded, resulting in a uniform electric field distribution and significantly improved insulation safety margin.

2.Reliable Winding Structure

The primary winding has a U-shaped structure. Models of 2×400A and below use paper-wrapped flat copper wire, while models of 2×500A~2×1000A use double semi-circular aluminum tubes, providing strong current carrying capacity. The winding is divided into two sections with four terminals, allowing flexible switching between dual current ratios.

3.Fully Sealed Protection Design

A metal expansion tank is installed at the top to automatically compensate for the expansion and contraction of transformer oil volume caused by temperature changes, isolating it from internal and external air, preventing moisture and oil aging, and extending equipment lifespan.

4.Convenient Installation and Maintenance

Pre-drilled lifting holes at the bottom of the tank facilitate equipment hoisting; multiple grounding bolts ensure reliable grounding of the equipment and secondary windings; the junction box is equipped with dedicated clamps for standardized and safe wiring.

Core Technical Parameters

1.Rated Parameters

Rated operating voltage 110kV, maximum operating voltage 126kV, rated frequency 50Hz, polarity is subtractive.

2.Insulation Withstand Voltage Level

Internal insulation primary to secondary and ground 185kV/1min, secondary to ground 3kV/1min; external insulation dry test voltage 230kV, wet test voltage 185kV, high-altitude anti-pollution lightning impulse withstand voltage peak reaches 560kV.

3.Accuracy Performance

0.2/0.5 grade metering error, minimal phase difference, meeting high-precision metering requirements; low composite error for 5P/10P protection level, enabling rapid response to grid fault currents.

4.Short-Circuit Resistance Performance

Thermal stability current 5.3KA~45KA, dynamic stability current 13KA~115KA, capable of withstanding grid short-circuit impacts and exhibiting strong operational stability.

Actual Engineering Application Cases:

Case: Zhejiang 110kV Urban Substation Upgrade Project

In 2024, the Zhejiang Jiaxing suburban 110kV substation upgrade project involved the bulk purchase of 32 Usune LB6-110kV-2×300/5 (5P30/5P30/0.5) current transformers. Located in an industrial cluster with large load fluctuations, the project required extremely high metering accuracy and protection sensitivity. After commissioning, the equipment can accurately collect bus current data, enabling real-time load monitoring and rapid fault tripping. Annual operational data shows that the metering error is far below the national standard limit, and the protection actions are accurate and reliable, completely resolving the metering inaccuracies of older equipment.

Installation, Operation, and Maintenance Specifications

1.Pre-Installation Inspection

Before installation, a visual inspection is required to eliminate defects such as damaged porcelain bushings, oil leaks, and mismatched nameplate parameters; verify that the expander oil level matches the ambient temperature, and add qualified transformer oil (electrical strength ≥45kV) if the oil level is low.

2.Installation Requirements

The equipment must be transported and hoisted vertically throughout the entire process, with a transport tilt angle ≤15°. Hoisting is only permitted through the bottom hoisting holes; stress on the porcelain bushings and oil conservator is strictly prohibited. The maximum horizontal tensile force at the primary terminal P1 is ≤2000N, and at P2 it is ≤3000N; the equipment body and shielding layer must be reliably grounded to ensure operational safety.

3.Operation and Maintenance Rules

During operation, the secondary winding must not be open-circuited to avoid high-voltage risks and equipment damage. The fully sealed structure requires no maintenance under normal operating conditions. Check the cleanliness of the porcelain bushing and oil level quarterly. If the seal is damaged or the insulation is damp, return the unit to the factory for vacuum drying and oil replacement immediately.

4. Storage Requirements

The 110 kV Current Transformer must be stored in a dry, well-ventilated environment, avoiding direct sunlight and rain. The bottom of the oil tank should be at least 50 mm above the ground, and the storage temperature should be at least -30℃. After one year of storage, insulation resistance and dielectric loss coefficient should be tested periodically. If the paint peels off after prolonged storage, repainting should be done promptly.

LB 6 - 110 kV appearance and installation dimensions

Project Reference

Cas-space Rocket Launch Project

Test Report

FAQ

Q1: How to switch the dual current ratio on the LB6-110 kV Current Transformer?

No equipment replacement is required. Simply adjust the wiring method of the external connector on the top oil conservator: when the primary windings are connected in series, the base current ratio is a/c; when connected in parallel, it is double the current ratio 2*a/c. Operation is simple and requires no specialized equipment, adaptable to different load conditions, effectively reducing equipment replacement costs.

Q2: What are the differences between the standard, anti-pollution, and high-altitude models?

The three models share the same core electrical performance, with structural optimizations tailored to specific scenarios: ① The standard model is suitable for conventional environments up to 1000m altitude, with a creepage distance of 16mm/KV; ② The W2 anti-pollution model is suitable for coastal and industrially polluted areas, with a creepage distance of 20mm/KV and enhanced corrosion and pollution resistance; ③ The GYW high-altitude model is suitable for high-altitude areas up to 4000m, with a maximum creepage distance of 31mm/KV, and can withstand low air pressure and strong ultraviolet radiation environments.

Q3: What are the core safety precautions for long-term equipment operation?

First, the secondary winding must be operated under load or short-circuited; open circuits are strictly prohibited to prevent high-voltage breakdown and personal injury accidents. Second, ensure reliable grounding of the junction box and the bottom grounding bolt of the oil tank, and that the grounding wire meets specifications to avoid static electricity buildup. Third, during normal operation, disassembly of the sealed structure and arbitrary sampling are prohibited. Regularly test dielectric loss and partial discharge data to ensure stable insulation performance.

Product Advantages and Service Guarantee

As a professional manufacturer and supplier of high-voltage power equipment in China, Usune Electric's LB6-110 kV Current Transformer boasts significant advantages: standardized factory production, strictly adhering to domestic and international industry standards, ensuring stable accuracy and strong environmental adaptability; and a fully sealed, maintenance-free design, significantly reducing subsequent operation and maintenance costs. The company provides a one-stop service including selection and customization, technical guidance, on-site installation, and after-sales maintenance. Parameters can be optimized according to project needs, providing reliable assurance for the safe and stable operation of the 110kV power grid system.