Overview
The LFC-10 / LFC(D)-10 is an indoor wall-through type current transformer with porcelain insulation, designed for 10kV, 11kV, and 12kV medium-voltage AC systems. It features a multi-turn primary through-wall structure, enabling installation where the primary conductor must pass through switchgear walls or partitions while maintaining required electrical clearances.
This CT supports current measurement, energy metering, relay protection, and differential protection applications. It complies with IEC 61869-1 and IEC 61869-2 standards, offering class 0.5 accuracy for metering and class B performance for protection circuits. The secondary output is standardized at 5A, with rated primary currents ranging from 30A to 400A across two groups.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 10kV / 11kV / 12kV |
| Rated insulation level | 12/42/75kV (IEC 12kV-class) |
| Rated frequency | 50Hz (60Hz optional) |
| Rated secondary current | 5A |
| Rated primary current | 30–150A, 200–400A |
| Short-time thermal current | 75 × I1n |
| Measurement accuracy class | 0.5 |
| Protection accuracy class | B |
| Insulation material | Porcelain |
| Application types | Measurement, metering, relay protection, differential protection |
| Standards | IEC 61869-1, IEC 61869-2 |
| Mounting type | Panel-mounted on switchgear wall or partition |
Model Designation
- L: Current transformer
- F: Multi-turn type
- C: Porcelain-insulated type
- (D): Differential protection configuration
- 10: Voltage class identification; suitable for 10kV systems and IEC 12kV-class insulation coordination for 10kV, 11kV, and 12kV projects
Construction
The LFC-10 / LFC(D)-10 features a robust indoor multi-turn wall-through construction. The primary conductor is formed as a multi-turn loop passing through the switchgear wall or insulated partition, encapsulated within a high-strength porcelain insulator. This design ensures reliable electrical clearance and creepage distance in confined cabinet environments. The current transformer body is mounted directly onto a panel or mounting plate, with the secondary winding housed in a sealed terminal compartment. The porcelain insulation provides stable dielectric performance under indoor medium-voltage operating conditions, while the multi-turn primary configuration enables accurate transformation ratios for lower current ranges from 30A to 400A.
Technical Parameters
Service Conditions
- Installation location: indoor medium-voltage switchgear or wall-through cabinet structure
- System voltage: 10kV, 11kV, or 12kV class
- Rated frequency: 50Hz / 60Hz according to project requirement
- Rated insulation level: 12/42/75kV reference for IEC-style applications
- Installation form: wall-through / partition-through mounting
- Installation environment: should be free from severe pollution, corrosive gas, explosive medium, heavy conductive dust, and abnormal condensation
- Special conditions: for high altitude, high humidity, coastal, high-pollution, or special switchgear applications, technical confirmation is recommended before ordering
Technical Parameters
The LFC(D)-10 is an indoor multi-turn wall-through cast-resin current transformer designed for 10kV–12kV medium-voltage systems. It complies with IEC 61869-1/-2 standards and features a rated primary current range of 30A to 400A, 5A secondary output, and standard insulation level of 12/42/75kV. The unit is suitable for indoor environments without extreme temperature, humidity, or contamination.
Current transformers are in accordance with the Chinese Standard GB 1208-75.
| Parameter | Rated Primary Current 30, 50, 75, 100, 150 (A) |
Rated Primary Current 200, 300, 400 (A) |
|---|---|---|
| Rated Secondary Current (A) | 5 | |
| Frequency (Hz) | 50 | |
| Rated Output (VA) | 10 | |
| For Accuracy Class 0.5 | 15 | |
| For Accuracy Class B | 30 | |
| Insulation Level (kV) | 10/42/75 | |
| Rated Short-Time Thermal Current Ith (kA) | 75 I1n | |
| Rated Dynamic Current Idyn (kA) | 2.5 Ith | |
| 10% Multiple | 10 | 15 |
Installation & Wiring
Installation Diagram
The LFC(D)-10 is designed for indoor wall-through installation, where the primary conductor passes through a switchgear wall or cabinet partition. The unit is secured via a mounting plate with four φ15 reference holes and auxiliary M8 fixing positions. Wall opening dimensions, mounting plate size, and terminal access must align with the approved outline drawing prior to installation.
Selection & FAQs
Selection Guide
- Select the exact 30/5A to 400/5A ratio from feeder loading. This is a fixed-5A, multi-turn-primary family; include normal load, future capacity and the usable range of the connected instrument or relay.
- Define measurement and protection duties separately. The published reference is 10VA at class 0.5 and 15VA for class B protection, but the final winding arrangement and burden must be confirmed for LFC-10 or LFC(D)-10.
- Translate legacy protection data into the relay study. Class B and the listed 10% multiple of 10 or 15 are legacy parameters; request the excitation curve, winding resistance and other data needed to validate differential or overcurrent performance.
- Check short-circuit capability against the network. Use 75 × rated primary current for short-time thermal current and 2.5 × Ith for dynamic current only as preliminary references, then confirm duration and certified values for the selected ratio.
- Resolve construction and mounting details before ordering. The page describes porcelain insulation but one parameter paragraph says cast resin; verify material, 12/42/75kV insulation, four Ø15 mounting holes, M8 fixing points, opening and terminal access from approved documents.
Frequently Asked Questions
Q1: What is the primary application of the LFC(D)-10 current transformer?
It is designed for indoor medium-voltage switchgear and wall-through cabinets. This cast-resin unit measures current in 10kV to 12kV systems. Contact us for specific project applications.
Q2: Which rated primary currents are available for this wall-through CT?
Standard primary current options range from 30A to 400A with a 5A secondary output. Exact ratios depend on your specific load requirements. Please provide your exact primary current for factory confirmation.
Q3: Can this indoor current transformer be installed in high-pollution areas?
Standard models require environments free from severe pollution and corrosive gases. For high-pollution, coastal, or high-humidity locations, special technical confirmation is required before ordering. Contact our engineering team for customized solutions.
Q4: Are IEC standards met by this 10kV current transformer?
Yes, the LFC(D)-10 complies with IEC 61869-1 and IEC 61869-2 standards. It also meets Chinese Standard GB 1208-75. Specify your required standard during the inquiry process.
Q5: What is the rated insulation level for this 12kV transformer?
The standard rated insulation level is 12/42/75kV for IEC-style applications. It features a wall-through or partition-through mounting design. Confirm exact insulation requirements with our technical team for non-standard switchgear.
Q6: How do I specify the rated frequency for my project?
The unit supports both 50Hz and 60Hz rated frequencies according to project requirements. Clearly state your grid frequency in the purchase order. Final acceptance is subject to factory verification.
Q7: Why choose a cast-resin design for this indoor CT?
It is an indoor multi-turn cast-resin current transformer. This dry-type design ensures safe wall-through installation in 10kV to 12kV indoor switchgear. Contact sales for detailed technical drawings.