Article Content
Application Note and Selection Criteria: LB-10W Outdoor Oil-Immersed Current Transformer
Overview
The LB-10W is an outdoor oil-immersed current transformer designed for 10kV power systems, providing accurate current measurement and protection functions in medium voltage applications. This transformer is specifically engineered for harsh outdoor environments while maintaining high accuracy and reliability.
Primary Application Scenarios
- Substation Monitoring: Primary application in 10kV distribution substations for metering and protection
- Feeder Protection: Used in outgoing feeder lines for overcurrent and ground fault protection
- Revenue Metering: Suitable for utility billing applications with appropriate accuracy class
- Industrial Power Systems: Integration into industrial facility power monitoring systems
System Topology Integration
The LB-10W integrates into typical 10kV radial or ring main distribution networks:
| Component | Connection Point | Function |
|---|---|---|
| Primary Conductor | P1/P2 Terminals | Carries system current through transformer core |
| Secondary Windings | S1/S2 Terminals | Provides scaled current output to connected devices |
| Grounding Point | Dedicated terminal | Single-point grounding per IEC 61869 requirements |
Comprehensive Selection Criteria
| Parameter | Consideration | Impact |
|---|---|---|
| Rated Voltage | Must match system voltage (10kV) | Ensures proper insulation coordination |
| Rated Current | Select based on maximum load current | Affects accuracy and thermal performance |
| Accuracy Class | 0.2/0.5 for metering, 5P/10P for protection | Determines measurement precision |
| Burden Rating | Total connected burden ≤ transformer rating | Prevents saturation and accuracy degradation |
| Environmental Rating | Outdoor installation, IP rating consideration | Ensures long-term reliability in harsh conditions |
Environmental Considerations
- Temperature Range: Designed for -25°C to +40°C ambient conditions
- Altitude: Rated for installations up to 1000m above sea level
- Humidity: Suitable for daily average humidity ≤95%, monthly average ≤90%
- Pollution Degree: Outdoor installation requires consideration of local pollution levels
- Oil Immersion: Provides superior cooling and insulation properties compared to dry-type transformers
Standards Compliance
- IEC 61869: Instrument transformers general requirements
- IEC 60044-1: Current transformers specifications
- Local electrical safety regulations
- IEEE C57.13: Standard for instrument transformers
Key Performance Characteristics
- Accuracy: Maintains specified accuracy class across full operating range
- Linearity: Excellent linearity characteristics for precise measurement
- Thermal Stability: Stable performance across temperature variations
- Long-term Reliability: Oil-immersed design provides superior aging characteristics
- Maintenance Requirements: Minimal maintenance required with proper installation