Overview
The LZZBJ9-10(225b) is an indoor epoxy cast-resin, fully enclosed support-type current transformer designed for 10kV, 11kV and 12kV class medium-voltage AC power distribution systems. It uses dry-type epoxy resin insulation to provide reliable dielectric strength, mechanical robustness, and resistance to indoor environmental conditions such as humidity and pollution.
This high-current CT supports rated primary currents from 3000A to 5000A and delivers a standardized secondary output for accurate measurement, energy metering, feeder monitoring, and relay protection. Typical accuracy combinations include 0.2S/5P, 0.2/5P, and 0.5/5P, meeting standard requirements for both metering and protection applications in main incoming and high-current feeder switchgear panels.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 10kV / 11kV / 12kV |
| Rated insulation level | 12/42/75kV |
| Rated frequency | 50Hz |
| Rated primary current | 3000A – 5000A |
| Rated secondary current | 5A (standard) |
| Rated output | 30VA |
| Short-time thermal current | 63kA (1s) |
| Dynamic current | 160kA |
| Accuracy classes | 0.2S, 0.2, 0.5 (metering); 5P (protection) |
| Insulation type | Epoxy cast-resin |
| Installation type | Indoor, support-mounted |
| Application | Main incoming, high-current feeders, busbar monitoring |
Model Designation
- L: Current transformer
- Z: Indoor type / support structure
- Z: Epoxy resin casting insulation
- B: Protection level available
- J: Strengthened design
- 9: Design serial number
- 10: 10kV catalogue voltage class (applicable to 10kV, 11kV and 12kV systems with proper insulation coordination)
- 225b: Large-width high-current structure dimension code
Construction
The LZZBJ9-10(225b) features a monolithic epoxy cast-resin body that fully encapsulates the annular magnetic core, primary conductor, and secondary windings. This dry-type construction eliminates the need for oil or gas insulation and provides excellent electrical insulation, mechanical stability, and resistance to tracking under indoor polluted or humid conditions. The 225b body width accommodates larger primary terminals and enhanced busbar interfaces required for high-current applications. All live parts are embedded within the resin matrix, ensuring safe touch surfaces and long-term operational reliability in medium-voltage switchgear environments.
Technical Parameters
Service Conditions
- Installation location: indoor medium-voltage switchgear
- System voltage: 10kV, 11kV and 12kV class networks
- Rated frequency: 50Hz
- Ambient temperature: -5°C to +40°C
- Installation environment: The installation environment should be free from severe vibration, conductive dust, corrosive gas, explosive medium, heavy pollution and abnormal condensation.
- High-current considerations: For high-current applications, temperature rise, busbar connection and ventilation conditions shall be reviewed together with the switchgear design.
- Special environments: For high altitude, coastal or special service environments, insulation coordination and creepage distance shall be confirmed before ordering.
Technical Parameters
The LZZBJ9-10(225b) is an indoor epoxy cast-resin high-voltage current transformer designed for 10kV, 11kV, and 12kV class systems. It features a rated primary current range of 3000–5000A, epoxy resin insulation, and compliance with GB 20840.2-2014 and IEC 61869-2:2012 standards.
| Rated primary current (A) |
Accuracy classed combination |
Rated Output (VA) |
Short-time thermal current (kA/1s) |
Rated dynamic current (kA) |
|---|---|---|---|---|
| 3000~5000 | 0.2S/5P10/5P20 0.2/5P10/5P20 0.5/5P10/5P20 0.5/5P20/5P20 0.2/0.5/5P10/5P20 0.2/0.5/5P20/5P20 0.5/5P20/5P20/5P20 |
30 | 63 | 160 |
Installation & Wiring
Installation
The LZZBJ9-110(225b) indoor epoxy cast-resin high-voltage current transformer features a large support-type body designed for high-current applications. Installation must be coordinated closely with the switchgear busbar layout to ensure proper mechanical fit and electrical performance.
Different primary terminal layouts are provided for three current ranges: 5A–1200A, 1200A–3000A, and 4000A–5000A. For this high-current model, the 4000A–5000A layout is critical and must be verified against the actual busbar design before copper busbar fabrication or switchgear assembly begins.
Mounting holes must align precisely with the switchgear structure as specified in the approved outline drawing. The overall large-width body requires adequate cabinet clearance and structural support to handle the approximate 69kg weight during installation and operation.
All secondary terminals must be clearly identified and matched to their designated functions (metering, protection, etc.) before connecting any instrumentation. Ensure that shorting blocks are installed and functional prior to any maintenance activity involving secondary circuit disconnection.
Selection & FAQs
Selection Guide
- Confirm a 3000A–5000A main-incomer, bus-coupler or feeder duty and verify continuous-current temperature rise with the complete switchgear design.
- Select the exact primary ratio and approve the 225b high-current terminal contact area, busbar width, bolt spacing and electrodynamic support.
- Specify each core separately as 0.2S/0.2/0.5 metering or 5P10/5P20 main and backup protection, including terminal assignment.
- Verify whether the 30VA reference applies per core, then calculate device and lead burden and confirm FS/ALF on the factory data sheet.
- Check 63kA/1s and 160kA withstand, 12/42/75kV insulation, 69kg reference weight, cabinet ventilation, clearances and lifting method.
Frequently Asked Questions
Q1: What is the maximum rated primary current for this cast-resin current transformer?
It supports a rated primary current range of 3000A to 5000A. This high-current capacity is designed for indoor medium-voltage switchgear applications. Specify your exact primary current requirement when ordering.
Q2: Can this indoor current transformer be installed in high-pollution or corrosive environments?
No, the installation environment must be free from corrosive gas, conductive dust, and severe vibration. For special environments like coastal areas, insulation coordination must be confirmed with the factory prior to ordering.
Q3: How are high-current applications and temperature rise managed during switchgear integration?
High-current applications require careful review of temperature rise, busbar connections, and ventilation conditions. These factors must be evaluated together with your specific switchgear design. Contact our engineering team for detailed thermal calculations.
Q4: Which international and national standards does this 10kV current transformer comply with?
The LZZBJ9-10(225b) fully complies with both GB 20840.2-2014 and IEC 61869-2:2012 standards. Request the specific type test reports and compliance certificates from our sales team before finalizing your procurement.
Q5: What documentation is provided to verify compliance for this epoxy cast-resin transformer?
Manufacturing adheres strictly to IEC 61869-2:2012 and GB 20840.2-2014 standards. For specific factory acceptance testing protocols or customized inspection requirements, please contact our quality department for details.
Q6: What type of switchgear application is the LZZBJ9-10(225b) current transformer designed for?
It is specifically designed for indoor medium-voltage switchgear in 10kV, 11kV, and 12kV class networks. Ensure the ambient temperature remains between -5°C and +40°C during operation. Verify site conditions with our technical team if outside this range.