Overview
The LA-10 (LFZ1-10, LFZB1-10) is a semi-enclosed cast-resin wall-through current transformer designed for indoor medium-voltage distribution systems. It operates at a rated voltage up to 10kV (also suitable for 11kV and 12kV class applications upon project confirmation) and uses epoxy resin insulation to ensure reliable dielectric performance in confined switchgear environments.
This CT series supports current measurement, electric energy metering, and relay protection in 50Hz AC circuits. It complies with standard requirements for accuracy, insulation strength, and thermal stability, making it appropriate for use in ring main units, metering panels, and feeder cabinets where space constraints and safety are critical considerations.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 10kV, 11kV, 12kV |
| Rated insulation level | 11.5/42/75kV |
| Rated frequency | 50Hz |
| Rated secondary current | 5A |
| Primary current range | Up to 3000A (varies by model) |
| Insulation material | Epoxy resin cast |
| Structure type | Semi-enclosed (≤200A), fully enclosed (≥300A) |
| Installation | Indoor wall-through |
| Typical applications | Measurement, metering, protection |
Model Designation
- L: Current transformer
- A: Wall-through type
- 10: Rated voltage class of 10kV
- LFZ1-10 / LFZB1-10: Manufacturer-specific designations for cast-resin wall-through indoor variants
Construction
The LA-10 series features a robust wall-through construction where the primary conductor passes directly through the transformer body. Units rated at 200A and below utilize a semi-enclosed cast-resin structure, offering a balance between compactness and insulation performance. Models rated 300A and above adopt a fully enclosed cast-resin design to accommodate higher currents and provide enhanced mechanical and dielectric strength. The core and windings are encapsulated in high-quality epoxy resin, ensuring excellent insulation integrity, moisture resistance, and long-term reliability in indoor switchgear applications. Clear terminal markings maintain correct polarity during installation, supporting accurate metering and dependable protection functionality.
Technical Parameters
Service Conditions
- Altitude: not over 1000m above sea level
- Ambient temperature: -30°C to +40°C
- Relative humidity: less than 85% at 20°C
- Installation environment: Indoor installation only
- Environmental restrictions: No severe vibration, corrosive gas, explosive medium, or conductive contamination
Technical Parameters
The LA-10, LFZ1-10, and LFZB1-10 are semi-enclosed cast-resin wall-through current transformers rated for 10kV class indoor applications, with a primary current range from 5A to 1500A. They feature a cast-resin insulation system, operate within an ambient temperature of -30°C to +40°C, and are suitable for installations up to 1000m altitude.
Technical Data
- The current transformer can operate continuously at 1.1 times the rated current.
- Power-frequency withstand voltage: 42 kV between the primary winding and secondary winding/earth for 5 minutes; 2 kV between secondary windings and earth for 1 minute.
| Rated Primary Current (A) |
Rated Short-Time Thermal Current Ith/1s (kA) |
Rated Dynamic Current Idyn (kA Peak) |
Accuracy Class / Corresponding Output (VA) |
Rated Secondary Current (A) |
Frequency | Insulation Level (kV) |
|||
|---|---|---|---|---|---|---|---|---|---|
| 0.2 | 0.5 | 1 | 10P10 | ||||||
| 5, 10, 15, 20, 30, 40 50, 75, 100, 150, 200 |
90 I1n | 160 I1n | 5~10 | 10 | 10 | 15 | 5 | 50Hz | 11.5/42/75 |
| 300, 400 | 75 I1n | 135 I1n | |||||||
| 500 | 60 I1n | 110 I1n | |||||||
| 600, 800, 1000, 1500 |
50 I1n | 90 I1n | |||||||
Installation & Wiring
Installation Diagram
The LA-10, LFZ1-10, and LFZB1-10 current transformers are designed for indoor wall-through installation. Two distinct mounting configurations apply based on current range: Dimension A for 5–200A models and Dimension B for 300–1500A models. Ensure the panel cutout, hole center distance, conductor path, terminal orientation, and required clearances match the approved installation drawing before fabrication.
Selection & FAQs
Selection Guide
- Select the 5A–200A semi-enclosed or 300A–1500A fully enclosed structure from the exact ratio and environmental requirement.
- Choose the primary ratio from load, metering range and fault study; do not rely on the overview’s unsupported 3000A upper limit.
- Confirm the fixed 5A secondary and specify class 0.2, 0.5, 1 or 10P10 for each ordered winding.
- Obtain the actual VA rating and verify device plus wiring burden because the page supplies no numerical output table.
- Check Ith/Idyn multiples, 1.1× continuous-current capability, 11.5/42/75kV insulation, cutout, ≤1000m altitude and humidity.
Frequently Asked Questions
Q1: Can the LA-10 current transformer be installed outdoors?
No, it is strictly for indoor installation only. The service conditions require an environment free from corrosive gases and conductive contamination. Ensure your switchgear meets these environmental restrictions.
Q2: What is the maximum continuous operating current for this 10kV CT?
The transformer can operate continuously at 1.1 times its rated primary current. This ensures stable performance under normal load variations without exceeding thermal limits.
Q3: Which accuracy classes are available for the LA-10 series?
Accuracy classes and corresponding VA outputs vary by specific model and ratio. Please provide your exact primary current and metering requirements for factory confirmation.
Q4: What factory tests are performed before shipping the LA-10?
The unit is rated for a power-frequency withstand voltage of 42 kV for 5 minutes. Specific routine and type test certificates are subject to confirmation upon request.
Q5: Can the primary current be customized beyond 1500A?
The standard rated primary current range is 5A to 1500A. Custom ratios outside this range are subject to engineering evaluation. Contact our sales team for details.
Q6: What type of current transformer is the LFZB1-10 model?
It is a semi-enclosed cast-resin wall-through current transformer designed for 10kV class indoor applications. It features robust cast-resin insulation for reliable power-frequency withstand voltage.
Q7: How does high altitude affect the LA-10 installation requirements?
Standard installations are limited to altitudes not exceeding 1000m above sea level. For higher altitudes, derating factors apply and require specific factory confirmation before ordering.