Overview
The LQJ(C)-10 is an indoor semi-enclosed epoxy resin cast current transformer designed for 10kV–12kV medium-voltage systems. It uses epoxy resin as the primary insulation material, with the primary winding and part of the secondary winding integrally cast into a single resin body, while the ring core and remaining secondary winding are semi-exposed.
Suitable for AC systems operating at 50Hz or 60Hz, it supports applications including current measurement, energy metering, relay protection, and differential protection. The design complies with IEC 61869-1 and IEC 61869-2 standards and is intended for use in compact indoor switchgear such as air-insulated switchboards, metering cabinets, and feeder panels.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 10kV, 11kV, 12kV |
| Highest voltage for equipment | 12kV |
| Rated insulation level | 12/42/75kV |
| Rated frequency | 50Hz / 60Hz |
| Rated secondary current | 5A or 1A |
| Primary structure | Coiled-type |
| Insulation system | Epoxy resin cast |
| Application | Metering, protection, differential protection |
| Installation | Indoor switchgear |
| Applicable standard | IEC 61869-1 / IEC 61869-2 |
Model Designation
- L: Current transformer
- Q: Coiled type / coil-wound primary structure
- J: Enlarged capacity / enhanced secondary output configuration
- C: Differential protection configuration
- 10: Voltage class identification; applicable to 10kV systems and IEC 12kV-class insulation coordination for 10kV, 11kV, and 12kV projects
Construction
The LQJ(C)-10 features a semi-enclosed construction where the primary winding and a portion of the secondary winding are fully encapsulated in a solid epoxy resin cast body. This provides robust electrical insulation and mechanical stability for indoor medium-voltage environments. The ring-shaped magnetic core and the remaining section of the secondary winding are not fully enclosed, aligning with the semi-enclosed structural definition. Primary terminals are positioned on the top surface for vertical connection, while the secondary terminal block is mounted on the side to facilitate accessible wiring in confined switchgear compartments. The coiled primary design ensures accurate current transformation, particularly suited for lower primary current ratios. The overall build supports reliable performance under both normal operating conditions and fault-current scenarios required for protection functions.
Technical Parameters
Service Conditions
- Installation location: indoor medium-voltage switchgear
- System voltage: 10kV, 11kV, or 12kV class
- Rated frequency: 50Hz / 60Hz
- Rated insulation level: 12/42/75kV reference
- Altitude: not over 1000m under standard service conditions unless otherwise specified
- Ambient temperature: -5°C to +40°C
- Relative humidity: less than 85% at 20°C under reference conditions
- Vibration resistance: The product can be specified for vibration-resistant switchgear applications according to project requirements.
- Installation environment: The installation environment should be free from severe vibration beyond specification, corrosive gas, explosive medium, heavy pollution, and abnormal condensation.
Technical Parameters
The LQJ(C)-10 is a semi-enclosed epoxy resin cast current transformer designed for 10kV–12kV medium-voltage systems. It features cast-resin insulation, operates within an ambient temperature range of -5°C to +40°C, and is rated for altitudes up to 1000m. Compliant with IEC 61869-1/-2 standards, it supports primary currents from 5A to 600A with multiple accuracy class combinations and secondary current options.
| Parameter | LQJ-10 | LQJC-10 | ||
|---|---|---|---|---|
| Rated Primary Current (A) | 5~100 | 150~400 | 5~100 | 400, 500 |
| Rated Short-Time Thermal Current Ith/1s (r.m.s.) |
90 I1n | 75 I1n | 90 I1n | 75 I1n |
| Rated Dynamic
Current Idyn (Peak) |
25 I1n | 160 I1n | 25 I1n | 160 I1n |
| Accuracy Class and Corresponding Rated Output (VA) |
0.2/10P10 10/15 0.5/10P10 10/15 |
0.2/10P15 10/15 0.5/10P15 10/15 |
||
| Frequency (Hz) | 50 | |||
| Rated Secondary Current | 5A | |||
| Rated Insulation Level (kV) | 11.5/42/75 | |||
Installation & Wiring
Installation Diagram
The LQJ(C)-10 semi-enclosed epoxy resin cast current transformer is installed inside indoor switchgear. Mounting is performed using the integrated base structure, with primary terminals positioned at the top for connection to busbars or cable lugs, and secondary terminals accessible from the side via a terminal block. Ensure alignment with switchgear phase spacing, grounding provisions, and maintenance clearance as per the approved outline drawing.
Selection & FAQs
Selection Guide
- Use the wound-primary range for 5A–600A feeders. Choose the ratio from actual operating current and metering range; lower ratios benefit from the coiled primary rather than a single-turn busbar design.
- Define both secondary-core duties. Published combinations include 0.2/0.5, 0.5/0.5, 0.2/10P and 0.5/10P with 10VA–20VA outputs. State the accuracy and burden required for each core.
- Complete the protection-class specification. The source lists 10P without an accuracy limit factor; specify the full class, such as the project-required 10P value, and verify relay, lead and terminal burden.
- Account for the semi-enclosed construction. Install only in a clean, dry, controlled indoor compartment and assess condensation, dust, pollution, ventilation and access to the partly exposed core and secondary components.
- Approve electrical and mechanical details. Confirm 12/42/75kV insulation, partial-discharge requirement, short-time and dynamic current, top primary-terminal spacing, base mounting, side-terminal access, altitude and phase clearances.
Frequently Asked Questions
Q1: What are the ambient temperature limits for installing this epoxy resin CT?
The standard operating range is -5°C to +40°C. Ensure installation environments remain below 85% relative humidity and free from corrosive gases. Contact us for extreme climate configurations.
Q2: Can this cast resin CT be used in 12kV switchgear?
Yes, it is rated for 10kV, 11kV, or 12kV system classes. It features a 12/42/75kV insulation level for reliable indoor medium-voltage applications. Confirm exact system parameters with our engineering team.
Q3: Which accuracy classes are available for this 10kV current transformer?
Multiple accuracy class combinations are available to support primary currents from 5A to 600A. These options ensure precise measurement across various protection and metering requirements. Specific ratio configurations are subject to confirmation.
Q4: What factory tests are performed before shipping the LQJ(C)-10 CT?
All units undergo standard routine testing compliant with IEC 61869-1 and IEC 61869-2 standards. Special type tests or specific project requirements are subject to confirmation. Request the test certificate with your inquiry.
Q5: Are vibration-resistant options available for this current transformer?
Yes, vibration-resistant specifications can be configured according to specific project requirements. Standard units are designed for normal indoor switchgear environments. Provide your vibration parameters for factory evaluation.
Q6: Which applications suit the LQJ(C)-10 epoxy resin CT?
It is designed for current measurement and protection in indoor 10kV to 12kV medium-voltage switchgear. The semi-enclosed epoxy resin casting ensures reliable insulation in clean environments. This makes it ideal for standard industrial power distribution networks.
Q7: How does high altitude affect the installation of this 12kV CT?
Standard service conditions apply up to 1000m altitude. For installations exceeding this limit, derating or special design modifications are required. The epoxy resin insulation maintains stability within these standard environmental parameters.
Q8: Where can I source IEC compliant 10kV current transformers?
We manufacture semi-enclosed epoxy resin CTs fully compliant with IEC 61869 standards. Our 10kV to 12kV range serves global medium-voltage switchgear markets. Contact our export team for sourcing details.