Overview
The LMZBJ17-12L(Q)/170 is an indoor single-phase epoxy cast-resin current transformer designed for 10kV, 11kV, and 12kV class medium-voltage switchgear. It features a fully enclosed epoxy resin body with a large hollow through-window aperture, enabling cable, copper bar, or busbar-through installation while maintaining high insulation integrity and mechanical stability.
This transformer supports both metering (0.2S/0.5) and protection (5P10 to 5P30) accuracy classes, making it suitable for current measurement, energy metering, feeder monitoring, and relay protection in 50Hz or 60Hz AC systems. It complies with GB20840.1-2010, GB20840.2-2014, and IEC61869-2:2003 standards, ensuring reliable performance in industrial substations, commercial distribution rooms, and OEM switchgear assemblies.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 10kV / 11kV / 12kV |
| Insulation level | 12/42/75kV |
| Rated frequency | 50Hz / 60Hz |
| Primary current | 1500A – 5000A |
| Secondary current | 1A or 5A |
| Metering accuracy | 0.2S, 0.5 |
| Protection accuracy | 5P10, 5P15, 5P20, 5P25, 5P30 |
| Construction | Epoxy cast-resin, fully enclosed |
| Application | Indoor medium-voltage switchgear |
| Standards | GB20840.1-2010, GB20840.2-2014, IEC61869-2:2003 |
Model Designation
- L: Current transformer
- M: Busbar / cable-through structure
- Z: Epoxy resin casting insulation
- B: Protection-class configuration available
- J: Enhanced / reinforced structure series
- 17: Design sequence code
- 12: Rated voltage class: 12kV
- Q: Reinforced type / structural variant
- 170 / L: Aperture or installation dimension reference used for variant selection
Construction
The LMZBJ17-12L(Q)/170 features a robust cylindrical epoxy cast-resin body that fully encapsulates the magnetic core and secondary windings. The primary conductor—whether cable, copper bar, or busbar—passes through a large central hollow aperture without electrical contact. This design ensures excellent dielectric strength, moisture resistance, and long-term dimensional stability under indoor operating conditions. Secondary terminals are mounted on the front face for easy access and secure connection to metering, protection, or monitoring equipment. The square mounting base provides stable mechanical fixation within switchgear panels, accommodating high-current applications while maintaining compactness and reliability.
Technical Parameters
Service Conditions
- Installation location: indoor medium-voltage switchgear
- System voltage: 12kV class networks
- Rated frequency: 50Hz
- Ambient temperature: -5°C to +40°C
- Installation environment: should be free from severe vibration, conductive dust, corrosive gas, explosive medium, heavy pollution and abnormal condensation.
Technical Parameters
The LMZBJ17-12L(Q)/170 is an indoor epoxy cast-resin busbar-type current transformer designed for 12kV class systems. It features multiple accuracy class combinations and complies with GB 20840.2-2014 and IEC 61869-2:2012 standards.
Dual Winding Configuration (Total Height: 230mm)
| Rated current ratio (A) |
Accuracy classed combination |
Rated Output (VA) |
|
|---|---|---|---|
| Class 1 | Class 2 | ||
| 1500/1 | 0.2S/5P15 | 15 | 30 |
| 0.2S/5P20 | 15 | 20 | |
| 0.2S/5P25 | 15 | 15 | |
| 0.2S/5P30 | 15 | 10 | |
| 2000/1 | 0.2S/5P15 | 15 | 40 |
| 0.2S/5P20 | 15 | 30 | |
| 0.2S/5P20 | 15 | 20 | |
| 0.2S/5P30 | 15 | 15 | |
| 3000/1 | 0.2S/5P15 | 20 | 40 |
| 0.2S/5P20 | 20 | 25 | |
| 0.2S/5P20 | 20 | 15 | |
| 4000/1 | 0.2S/5P15 | 30 | 40 |
| 0.2S/5P20 | 30 | 25 | |
| 0.2S/5P20 | 30 | 15 | |
| 5000/1 | 0.2S/5P15 | 30 | 10 |
Triple Winding Configuration (Total Height: 270mm)
| Rated current ratio (A) |
Accuracy classed combination |
Rated Output (VA) |
||
|---|---|---|---|---|
| Class 1 | Class 2 | Class 3 | ||
| 1500/1 | 0.2S/5P10/5P10 | 10 | 40 | 40 |
| 0.2S/5P15/5P15 | 10 | 25 | 25 | |
| 0.2S/5P20/5P20 | 10 | 15 | 15 | |
| 2000/1 | 0.2S/5P10/5P10 | 10 | 50 | 50 |
| 0.2S/5P15/5P15 | 10 | 30 | 30 | |
| 0.2S/5P20/5P20 | 10 | 20 | 20 | |
| 3000/1 | 0.2S/5P10/5P10 | 10 | 50 | 50 |
| 0.2S/5P15/5P15 | 10 | 30 | 30 | |
| 0.2S/5P20/5P20 | 10 | 15 | 15 | |
| 4000/1 | 0.2S/5P10/5P10 | 15 | 50 | 50 |
| 0.2S/5P15/5P15 | 15 | 30 | 30 | |
| 0.2S/5P20/5P20 | 15 | 15 | 15 | |
| 5000/1 | 0.2S/5P10/5P10 | 10 | 15 | 15 |
Installation & Wiring
Installation Diagram
This current transformer is installed in indoor switchgear with the primary conductor (cable or busbar) passing through the central aperture. The unit is mounted on a support plate using the provided mounting holes, ensuring proper phase clearance, creepage distance, and alignment with the conductor path. Terminal direction and secondary wiring access must be verified against the approved layout drawing before cabinet fabrication.
Selection & FAQs
Selection Guide
- Verify the actual 170-type aperture and conductor-group clearance from the approved drawing; do not infer exact diameter from the suffix alone.
- Select 1500A, 2000A, 3000A, 4000A or 5000A from continuous-current, temperature-rise and fault-duty studies.
- Choose 1A or 5A and specify four cores: 0.2S metering, 0.5 measurement and two identical 5P protection duties.
- Calculate each burden and select the complete four-value output; resolve the 75VA summary versus 60VA table maximum.
- Approve Q/170 or 230/270mm axial-length variant, four-Ø14 mounting, terminal access, conductor support, grounding and current standard edition.
Frequently Asked Questions
Q1: What are the installation environment requirements for this 12kV busbar CT?
Installation must be indoors, free from conductive dust, corrosive gases, and severe vibration. The ambient temperature should range from -5°C to +40°C. Confirm specific site conditions with our engineering team.
Q2: How to select the accuracy class for metering and protection?
The dual winding configuration offers 0.2S for metering and 5P for protection. Rated outputs range from 10VA to 40VA depending on the accuracy limit factor. Specify your exact ratio and burden requirements.
Q3: Can this cast-resin current transformer operate on 60Hz power systems?
This model is specifically designed for 50Hz rated frequency networks. Using it on 60Hz systems may affect accuracy and thermal performance. Request a custom 60Hz evaluation from our factory.
Q4: Which international standards does this epoxy cast-resin CT comply with?
The transformer fully complies with GB 20840.2-2014 and IEC 61869-2:2012 standards. These specifications ensure reliable electrical performance and safety in 12kV class networks. Detailed compliance certificates are provided upon request.
Q5: Are custom current ratios available beyond 1500/1 and 2000/1?
Standard configurations include 1500/1 and 2000/1 with various 0.2S/5P combinations. Custom current ratios and accuracy class combinations are available subject to factory confirmation. Contact our sales team for specific project requirements.
Q6: Where is the LMZBJ17-12L busbar type primarily applied?
It is an indoor medium-voltage switchgear current transformer designed for 12kV class networks. The epoxy cast-resin busbar design ensures compact integration. Verify physical dimensions with your switchgear layout.
Q7: Why choose an epoxy cast-resin design for indoor switchgear?
Cast-resin insulation provides excellent mechanical strength and partial discharge resistance for indoor 12kV applications. It requires minimal maintenance in clean environments. Consult our technical team for dimensional drawings.