Overview
The LZZBJ9-10C1 / LZZBJ9-10C2 and LZZBJ9-12C1 / LZZBJ9-12C2 are indoor, single-phase, epoxy resin cast, fully enclosed post-type current transformers designed for 10kV to 12kV medium-voltage switchgear applications. They support current measurement, energy metering, feeder monitoring, and relay protection in AC systems operating at 50Hz or 60Hz.
Encapsulating the primary winding, secondary winding, and annular magnetic core within a solid epoxy resin body ensures high insulation strength, moisture resistance, mechanical stability, and compact installationâideal for space-constrained indoor switchgear environments.
Key Ratings Snapshot
| Parameter | Value |
|---|---|
| Voltage Class | 10kV / 11kV / 12kV |
| Rated Insulation Level | 12/28/75kV or 12/42/75kV |
| Rated Frequency | 50Hz / 60Hz |
| Rated Secondary Current | 1A or 5A |
| Transformation Ratio | 10:3150/5 (single or double ratio) |
| Accuracy Classes | 0.2S / 0.5 / 10P combinations |
| Rated Output | 10VA / 15VA / 20VA |
| ALF (Protection) | 10 / 15 / 20 |
| Metering FS | 5 or 10 |
| Installation Type | Indoor post-type |
Model Designation
- L: Current transformer
- Z: Indoor type
- Z: Cast-resin insulated / fully enclosed
- B: Dual use for metering and protection
- J: Reinforced design / enhanced insulation
- 9: Design sequence / platform
- 10 / 12: Rated voltage class (for 10kV, 11kV, or 12kV systems)
- C1 / C2: Mechanical and terminal configuration variants
Construction
The transformer features a monolithic epoxy resin casting that fully encloses the primary conductor, secondary windings, and toroidal magnetic core. This construction delivers excellent dielectric performance, mechanical rigidity, and environmental protection against humidity and contaminationâcritical for reliable operation in indoor medium-voltage switchgear.
Available in C1 and C2 structural variants, the unit integrates both electrical transformation and mechanical support functions, enabling secure mounting directly onto switchgear busbars or insulating supports while maintaining phase-to-ground clearance and thermal stability under load.
Technical Parameters
Service Conditions
- Installation location: Indoor medium-voltage switchgear
- System voltage: 10kV, 11kV, or 12kV
- Rated frequency: 50Hz / 60Hz
- Ambient temperature: -5 deg to +40 deg C
- Altitude: <=1000m
- Environment: Free from severe vibration, conductive dust, corrosive gas, explosive media, heavy pollution, and abnormal condensation
Technical Data
| Rated Transformation Ratio (A) |
Accuracy Class Combination |
Rated Output Measuring 0.2S (VA) |
Rated Output Protection 10P (VA) |
ALF | FS | Ith 1s Short-Time Thermal Current |
Idyn Rated Dynamic Current |
|---|---|---|---|---|---|---|---|
| 10:200/5 | 0.2S / 10P | 10 or 15 | 15 | 10 / 15 / 20 | 5 or 10 | 150 x I1n | 375 x I1n |
| 300/5 | 0.2S / 10P | 10 or 15 | 15 | 10 / 15 / 20 | 5 or 10 | 31.5kA | 80kA |
| 500/5 | 0.2S / 10P | 10 or 15 | 15 | 10 / 15 / 20 | 5 or 10 | 40kA | 100kA |
| 800/5 | 0.2S / 10P | 10 or 15 | 15 | 10 / 15 / 20 | 5 or 10 | 63kA | 125kA |
| 1000/5 | 0.2S / 10P | 10 or 15 | 20 | 10 / 15 / 20 | 5 or 10 | 80kA | 160kA |
| 2000:2500/5 | 0.2S / 10P | 10 or 15 | 20 | 10 / 15 / 20 | 5 or 10 | 130kA | 160kA |
Installation & Wiring
Installation Diagram
The LZZBJ9 C1/C2 series is designed for direct post-type mounting in indoor switchgear. Installation must align with approved switchgear layout drawings to ensure proper phase clearance, busbar connection, and maintenance access. Terminal orientation and mounting hole positions vary by C1/C2 variant and voltage class.
Outline Dimensions
| Item | Specification |
|---|---|
| Mechanical Variant | LZZBJ9-10C1 / 10C2 / 12C1 / 12C2 |
| Mounting Type | Indoor post-type support |
| Primary Terminals | P1 / P2 per approved drawing |
| Secondary Terminals | 1S1/1S2, 2S1/2S2 (optional 3S1/3S2) |
| Dimension Confirmation | Required before switchgear production |
Selection & FAQs
Selection Guide
- Choose C1 or C2 from the switchgear interface. Terminal orientation and mounting positions vary, so use the variant-specific drawing before cabinet or busbar production.
- Select from the documented 5A-secondary ratios. The table provides representative 10A–200A, 300A, 500A, 800A, 1000A and 2000A–2500A groups; confirm intervening or 3150A ratings separately.
- Specify measuring output and FS together. The 0.2S core is offered at 10VA or 15VA with FS 5 or FS 10; choose according to metering burden and instrument-protection requirements.
- Define the complete protection core. Select 15VA or 20VA and ALF 10, 15 or 20 from the relay study, including lead resistance and the maximum protection current.
- Resolve voltage, secondary and mechanical details. Confirm 12/28/75kV or 12/42/75kV insulation, any 1A version, thermal duration, peak current, optional third core, terminals, dimensions and current IEC 61869 compliance.
Frequently Asked Questions
Q1: Can this epoxy resin CT be installed outdoors?
No, this model is strictly designed for indoor medium-voltage switchgear installations. It requires an environment free from severe vibration and corrosive gases. Contact us for outdoor-rated alternatives.
Q2: What is the rated short-time thermal current for the 500/5A ratio?
The 500/5A ratio provides a 1-second short-time thermal current (Ith) of 40kA and a rated dynamic current (Idyn) of 100kA. Verify your specific fault level requirements with our engineering team.
Q3: Which accuracy class combination is suitable for protection and metering?
The 0.2S/10P accuracy class combination is ideal. The 0.2S core handles precise metering, while the 10P core provides reliable protection with an accuracy limit factor (ALF) up to 20.
Q4: Are custom transformation ratios available for this current transformer?
Standard ratios include 300/5A, 500/5A, and 800/5A. Custom ratios and specific burden requirements are subject to factory confirmation. Please provide your exact project specifications for a tailored quote.
Q5: How can I request the type test report for this model?
Type test reports and specific certification documents are available upon request. Please contact our sales team with your project details to obtain the relevant compliance certificates for your region.
Q6: Where is the LZZBJ9-12 epoxy resin current transformer typically applied?
This indoor epoxy resin current transformer is designed for 10kV, 11kV, and 12kV medium-voltage switchgear systems. It operates at 50Hz or 60Hz rated frequencies up to 1000m altitude.
Q7: Why choose the LZZBJ9-12 for 12kV indoor switchgear?
The LZZBJ9-12 operates reliably in ambient temperatures ranging from -5°C to +40°C. Ensure the installation environment remains free from abnormal condensation and heavy pollution. Contact us for extreme climate applications.