Overview
The LA-10Q / LFZ-10Q / LFZB1-10Q is an indoor wall-through current transformer with epoxy resin cast insulation, designed for 10kV class medium-voltage AC systems. It supports operation in 10kV, 11kV, and 12kV indoor applications when insulation coordination and project-specific conditions are verified.
This series offers accuracy classes of 0.2, 0.5, 1, and 10P10, making it suitable for both metering and protection functions. Typical applications include current measurement, energy metering, relay protection, and switchgear instrumentation in distribution rooms and medium-voltage switchgear under humid, polluted, or condensation-prone indoor environments.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 10kV class (applicable to 10kV, 11kV, 12kV) |
| Rated insulation level | 11.5/42/75kV |
| Primary current range | 5–1500A |
| Secondary current | 5A |
| Metering accuracy classes | 0.2, 0.5, 1 |
| Protection accuracy class | 10P10 |
| Insulation material | Epoxy resin cast |
| Installation type | Wall-through, indoor |
| Structure types | Semi-enclosed (5–200/5A); fully enclosed (300–1500/5A) |
Model Designation
- L: Current transformer
- A: Wall-through type
- 10: Rated voltage class: 10kV class
- Q: Stiffening / reinforced type
- LFZ-10Q: Corresponding wall-through cast-resin CT designation
- LFZB1-10Q: Corresponding reinforced or fully enclosed wall-through cast-resin CT designation
Construction
The LA-10Q / LFZ-10Q / LFZB1-10Q features a wall-through design with epoxy resin casting insulation and a reinforced Q-type structure. Units with current ratios from 5–200/5A use a semi-enclosed cast-resin construction, optimized for compact installations and lower-current circuits. Models rated 300–1500/5A employ a fully enclosed cast-resin structure, delivering enhanced external insulation and mechanical robustness for higher-current applications. The resin-encapsulated core and windings provide reliable isolation between the medium-voltage primary and low-voltage secondary circuits, ensuring safe operation in challenging indoor environments including those with humidity, pollution, or condensation risks.
Technical Parameters
Service Conditions
- Installation location: indoor medium-voltage switchgear
- Rated frequency: 50Hz
- System voltage: 10kV class, with 10kV, 11kV and 12kV class project application subject to insulation confirmation
- Suitable for indoor environments where condensation, surface dew point, or tropical humidity may need to be considered
- Artificial pollution class: Class 2 reference
- The installation environment should be free from severe vibration, explosive medium, corrosive gas, heavy conductive dust, and abnormal mechanical stress.
Technical Parameters
The LA-10Q, LFZ-10Q, and LFZB1-10Q are wall-through cast-resin current transformers designed for 10kV class indoor switchgear applications. They feature a rated insulation level of 11.5/42/75kV, operate at 50Hz, and support primary current ranges from 5/5A to 1500/5A with accuracy classes including 0.2, 0.5, 1, and 10P10. The units comply with GB5583-85 and IEC 61869 (formerly IEC 44) standards and are suitable for standard indoor environmental conditions without extreme temperature, altitude, or contamination concerns beyond Class 2 artificial pollution.
| Rated Primary Current (A) |
Accuracy Class and Rated Output (VA) |
Rated Short-Time Thermal Current Ith/1s (r.m.s.) |
Rated Dynamic Current Idyn (Peak) |
|||
|---|---|---|---|---|---|---|
| 0.2 | 0.5 | 1 | 10P10 | |||
| 5, 10, 15, 20, 30, 40 50, 75, 100, 150, 200 |
5~10 | 10 | 10 | 15 | 90 I1n | 160 I1n |
| 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-10Q, LFZ-10Q, and LFZB1-10Q current transformers use a wall-through cast-resin installation method. The unit is mounted through a cut-out in the switchgear panel wall, with primary conductor passing through the center aperture. Mounting holes, overall dimensions, and terminal orientation vary by current range and structure type (semi-enclosed for 5-200/5A; fully enclosed for 300-1500/5A). Always refer to the approved outline drawing corresponding to the selected current ratio before cabinet fabrication or drilling.
Selection & FAQs
Selection Guide
- Select LA-10Q, LFZ-10Q or LFZB1-10Q from the approved outline and tender designation; the page does not fully map each name to every structure.
- Choose a 5/5A–200/5A semi-enclosed or 300/5A–1500/5A fully enclosed ratio from load and fault studies.
- Confirm the fixed 5A secondary and choose class 0.2, 0.5, 1 or 10P10 for the ordered winding/function.
- Verify the class-specific 5VA–25VA burden at power factor 0.8 and the ratio-specific Ith/Idyn multiples.
- Check 11.5/42/75kV insulation, ≤50pC partial-discharge requirement, Class 2 pollution, cutout, mounting and terminal direction.
Frequently Asked Questions
Q1: Are these wall-through current transformers suitable for 12kV switchgear applications?
Yes, subject to insulation confirmation. They are designed for 10kV class systems but support 11kV and 12kV applications. Specify your exact system voltage during inquiry.
Q2: How do these cast-resin current transformers handle high humidity environments?
They are specifically suited for indoor environments with condensation or tropical humidity. Ensure the installation site remains free from corrosive gases and severe vibration.
Q3: Which accuracy classes are available for metering and protection applications?
Available classes include 0.2, 0.5, 1, and 10P10. Select 0.2 or 0.5 for metering, and 10P10 for protection. Confirm exact VA output requirements with our engineering team.
Q4: What international standards do these current transformers comply with for procurement?
The units comply with GB5583-85 and IEC 61869 standards. Request the specific type test and routine test certificates during the bidding process.
Q5: Can we customize the primary current ratios for our specific projects?
Yes, primary currents range from 5/5A to 1500/5A. Custom ratios are available subject to factory confirmation. Provide your exact primary and secondary current requirements for a quote.
Q6: Where are these 10kV wall-through current transformers typically applied?
They are designed for indoor medium-voltage switchgear applications. Their wall-through cast-resin design ensures reliable current measurement in 10kV class power distribution networks.
Q7: When should engineers select the 10P10 accuracy class for these CTs?
Select 10P10 when protection relay accuracy is the primary requirement. This class maintains performance during high short-circuit currents. Verify your specific protection scheme details with our technical team.