Overview
The LZZBJ9-10E is an indoor single-phase epoxy cast-resin current transformer designed for 11kV and 12kV class medium-voltage switchgear. It features a compact rectangular body with epoxy resin insulation, top-mounted primary terminals, and a front-access secondary terminal box, suitable for standard indoor distribution panels.
This economy-type CT supports dual secondary windings for both metering (e.g., 0.2S accuracy) and protection (e.g., 5P or 10P class), making it ideal for feeder monitoring, energy metering, and relay protection in 50Hz AC systems. Final application suitability depends on system voltage, insulation level (12/42/75kV), and project-specific burden requirements.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 11kV / 12kV |
| Insulation level | 12/42/75kV |
| Rated frequency | 50Hz (60Hz by confirmation) |
| Primary current range | 5A – 800A |
| Secondary current | 5A or 1A |
| Metering accuracy | 0.2S, 0.2, or 0.5 |
| Protection class | 5P or 10P |
| Typical burden | 15VA (metering) |
| Phase | Single-phase |
| Indoor use | Yes |
| Insulation material | Epoxy cast-resin |
| Mounting | Compact base for cabinet installation |
Model Designation
- L: Current transformer
- Z: Indoor type / cast-resin insulated structure reference
- ZB: Epoxy cast-resin current transformer series
- J: Reinforced or structural design reference
- 9: Design sequence / product platform
- 10E: 10kV catalogue series, economy-type version; documented for 11kV / 12kV class projects by insulation confirmation
Construction
The LZZBJ9-10E features a solid epoxy cast-resin body that provides high dielectric strength, mechanical stability, and resistance to indoor environmental conditions such as humidity and dust. The primary conductor passes vertically through the center of the core and connects to top-mounted primary terminals. A front-mounted secondary terminal box houses separate terminals for measurement (e.g., 1S1–1S2) and protection (e.g., 2S1–2S2) windings, enabling clear circuit separation and simplified wiring access. The compact base allows secure mounting within standard switchgear panels without requiring additional structural support, distinguishing it from larger support-type CTs. All internal components are fully encapsulated in epoxy resin, ensuring long-term reliability and safety in indoor medium-voltage applications.
Technical Parameters
Service Conditions
- Installation location: indoor medium-voltage switchgear
- Rated voltage: 11kV and 12kV class systems by project confirmation
- Rated frequency: 50Hz; 60Hz by agreement
- Ambient temperature: -5°C to +55°C
- Indoor environment: should be free from conductive dust, corrosive gas, explosive medium, heavy pollution and abnormal condensation.
- Special environmental considerations: For high humidity, coastal, high altitude, heavy pollution or special cabinet layouts, insulation distance and creepage coordination should be confirmed before ordering.
Technical Parameters
The LZZBJ9-10E is an indoor economy-type epoxy cast-resin current transformer designed for 11kV and 12kV class systems with a rated primary current range of 5A–800A. It operates within an ambient temperature range of -5°C to +55°C and complies with IEC 61869-2 and GB20840.2-2014 standards. The unit features a 12/42/75kV insulation level and supports both metering (0.2S, 0.2, 0.5) and protection (5P, 10P) accuracy classes.
| Rated Primary Current (A) |
Accuracy Classes Combination |
Rated Output (VA) | Rated Short-Time Thermal Current (kA/1S) |
Rated Dynamic Current |
|||
|---|---|---|---|---|---|---|---|
| 0.2S | 0.2 0.5 |
5P | 10P | ||||
| 5~400 | 0.2/10P 0.2S/10P 0.5/10P |
10 | 10 | 15 | 15 | 60 I1n | 150 I1n |
| 600 | 50 I1n | 120 I1n | |||||
| 800 | 50 I1n | 100 I1n | |||||
Installation & Wiring
Installation Diagram
The LZZBJ9-10E is designed for compact indoor switchgear installation. It is mounted vertically using the bottom mounting holes, with primary conductors passing through the top terminals. Ensure adequate phase-to-ground clearance, secondary terminal accessibility, and alignment with busbar layout as per the approved installation drawing.
Selection & FAQs
Selection Guide
- Confirm a 12/42/75kV indoor application and that the compact 272×190×150mm reference body fits the panel.
- Select a listed 5A–400A, 600A or 800A ratio from load, metering range and fault study; confirm any omitted intermediate ratios.
- Choose 1A or 5A and order separate 0.2S/0.2/0.5 metering and 5P/10P protection windings.
- Verify the 10VA measurement and 15VA protection references against each circuit’s device and lead burden.
- Convert the ratio-specific Ith/Idyn multiples into amperes, then approve P1/P2 busbars, base holes, front-terminal access and +55°C duty.
Frequently Asked Questions
Q1: What accuracy class ensures compliance for revenue billing?
Select the 0.2S accuracy class for revenue billing. It ensures precise measurement across varying load conditions per IEC 61869-2. Confirm specific burden requirements with our engineering team.
Q2: Can this epoxy cast-resin CT operate in high humidity?
Standard units require a clean, condensation-free indoor environment. For high humidity or coastal sites, insulation distance and creepage coordination must be adjusted. Contact us for custom environmental specifications.
Q3: How is the short-circuit thermal capacity specified for this model?
The rated short-time thermal current is defined in the technical parameter table based on primary current. Verify the exact kA/1s rating and dynamic current capability. This ensures proper coordination with your switchgear protection relays.
Q4: Which international standards does this 12kV current transformer comply with?
The LZZBJ9-10E fully complies with IEC 61869-2 and GB20840.2-2014 standards. It features a 12/42/75kV insulation level suitable for medium-voltage switchgear. Request the specific type test report during procurement.
Q5: Is this 11kV transformer available for 60Hz power systems?
Yes, 60Hz operation is available by specific agreement. The standard rated frequency is 50Hz, but custom winding designs accommodate 60Hz networks. Specify your system frequency when placing the order.
Q6: Where is the LZZBJ9-10E current transformer typically installed?
This indoor economy-type epoxy cast-resin CT is designed for 11kV and 12kV medium-voltage switchgear. It supports both metering and protection functions with primary currents from 5A to 800A. It is ideal for standard indoor power distribution projects.
Q7: Are custom primary current ratios available beyond the 800A maximum?
The standard range covers 5A to 800A. For primary currents exceeding 800A, custom design and factory confirmation are required. Submit your exact technical inquiry for evaluation.