Overview
The LZZBJ9-10 series current transformers are precision electromagnetic devices engineered for accurate current measurement, energy metering, and relay protection in 10 kV indoor AC power systems. Operating on Faraday’s law of electromagnetic induction, they deliver galvanically isolated secondary current signals proportional to the primary current, ensuring reliable performance in medium-voltage switchgear.
Epoxy resin cast construction provides excellent insulation, moisture resistance, and mechanical robustness, making these transformers ideal for compact installations in constrained indoor environments such as ring main units, motor control centers, and distribution panels.
Key Ratings Snapshot
| Parameter | Value |
|---|---|
| System voltage class | 10 kV (indoor) |
| Rated frequency | 50 Hz (60 Hz on request) |
| Rated secondary current | 1 A or 5 A |
| Accuracy classes | 0.2S / 0.5 / 0.2 / 10P10 (as ordered) |
| Rated burden | Per core, specified in VA |
| Burden power factor | cos phi = 0.8 (lagging) |
| Short-circuit withstand | Ith (1 s) and Idyn (peak) per spec |
| Insulation | Epoxy resin cast, fully enclosed |
| Mounting type | Post-type (support pillar) |
| Standards compliance | IEC 61869-1/2, GB/T 20840.1/2 |
Model Designation
- L: Current transformer (CT)
- Z: Indoor support (pillar) type
- Z: Cast-resin (epoxy) insulated, fully enclosed
- B: Protection configuration available
- J: Reinforced design
- 9: Design code (platform/iteration)
- 10: Voltage class (kV)
- A / B / C: Mechanical variant code
Construction
The LZZBJ9-10 features a post-type support structure with fully enclosed epoxy resin cast insulation, ensuring superior dielectric strength, moisture resistance, and long-term stability in indoor environments. The ring-type magnetic core is optimized for low losses and high linearity across the operating range.
Integrated primary and secondary insulation systems maintain safe electrical clearances and creepage distances even in compact switchgear layouts. Terminal markings follow standard CT polarity conventions (P1/P2, 1S1/1S2, etc.) to guarantee correct metering and protection functionality.
Technical Parameters
Service Conditions
- Installation environment: Indoor only
- Altitude: <= 1000 m above sea level
- Ambient temperature: -5 deg C to +40 deg C
- Relative humidity: Daily average <= 95%, monthly average <= 90% (at +20 deg C)
- Environmental conditions: Free from corrosive gases, explosive media, severe vibration, or mechanical shock
Technical Data
| Rated Primary Current (A) |
Accuracy Class | Rated Output (VA) |
Short-time Thermal Current (Ith) |
Rated Dynamic Current (Idyn) |
|---|---|---|---|---|
| 5:100 | 0.2S / 10P10 | 10 / 15 | 150 x In | 375 x In |
| 150:200 | 0.2S / 0.5 / 10P10 | 10 / 15 / 15 | 21.5 kA | 54 kA |
| 300:400 | 0.5 / 10P10 | 10 / 15 | 31.5 kA | 80 kA |
| 500:600 | 0.2 / 10P10 | 10 / 15 | 45 kA | 112.5 kA |
| 800 | 0.2S / 10P10 | 10 / 15 | 63 kA | 130 kA |
| 1000 | 0.2S / 0.5 / 10P10 | 10 / 10 / 15 | 80 kA | 160 kA |
| 1200 | 0.5 / 10P10 | 10 / 15 | 80 kA | 160 kA |
| 1500 | 0.2S / 10P10 | 10 / 15 | 100 kA | 160 kA |
| 2000 | 0.2 / 10P10 | 10 / 15 | 100 kA | 160 kA |
Installation & Wiring
Installation Diagram
The LZZBJ9-10 series must be securely mounted using the designated fixing holes on the base. Primary connection is made via bolted terminals or busbar, depending on the mechanical variant. Maintain adequate clearance for insulation, heat dissipation, and maintenance access as per switchgear layout requirements.
Outline Dimensions
| Variant | Height (mm) | Width (mm) | Depth (mm) | Mounting Hole Pattern |
|---|---|---|---|---|
| LZZBJ9-10A | 886 | 822 | phi 120 | 4 x M12 |
| LZZBJ9-10B | 600 | 661 | phi 100 | 4 x M10 |
| LZZBJ9-10C | 528 | 677 | phi 90 | 4 x M10 |
Selection & FAQs
Selection Guide
- Confirm that the A mechanical variant fits the switchgear. A, B and C identify different primary interfaces and mounting structures; the page’s dimensional table is corrupted and cannot be used safely for fabrication.
- Select the ratio from the 5A–2000A reference schedule. Match continuous load and measurement range, then verify the exact ratio’s 1-second thermal and peak dynamic current.
- Choose two or three secondary cores. Standard rows combine measurement with 10P10, while 150A–200A and 1000A list three-core configurations for two measuring duties plus protection.
- Specify 1A or 5A secondary with the burden. The detailed table does not separate secondary options, so confirm ratio notation, per-core VA, cable losses, terminals and accuracy for the selected current.
- Complete the missing dielectric and mechanical specification. Obtain highest voltage, power-frequency and impulse withstand, partial discharge, creepage, certified outline, terminal size, mounting pattern and test report.
Frequently Asked Questions
Q1: What are the installation environment limits for this epoxy insulated CT?
This LZZBJ9-10A current transformer is strictly for indoor use. It operates between -5°C and +40°C at altitudes up to 1000m. Ensure the environment is free from corrosive gases and severe vibration.
Q2: Which accuracy class should I select for energy metering applications?
Select the 0.2S or 0.2 accuracy class for precise energy metering. The 10P10 class is suitable for protection relays. Ensure the selected class matches your connected secondary burden.
Q3: How does this 10kV CT handle short-circuit thermal currents?
Short-time thermal current ratings range from 150 x In up to 80 kA. This maximum rating depends on the specific primary current selected. Verify the exact dynamic and thermal parameters with our engineering team.
Q4: Can the rated primary current and accuracy classes be customized?
Yes, we offer various standard primary current ratios from 5A to 1200A with multiple accuracy class combinations. Custom ratios or specific accuracy requirements are subject to factory confirmation. Please contact us for details.
Q5: What factory tests are performed before shipping the LZZBJ9-10A?
Standard factory testing protocols are applied to ensure performance compliance. Specific routine tests, type tests, and certification documents are subject to confirmation based on your order. Contact our sales team for detailed test specifications.
Q6: What applications suit the LZZBJ9-10A epoxy insulated current transformer?
This 10kV indoor current transformer is ideal for current measurement and relay protection in power distribution panels. It integrates seamlessly into compact indoor switchgear. Contact our factory for application-specific technical drawings.