Overview
The LZZBJ9-10 A, B, and C are indoor-type current transformers rated for 10 kV medium-voltage systems. They feature a fully enclosed cast-resin (epoxy) insulation system, ensuring high dielectric strength, moisture resistance, and long-term reliability in controlled indoor environments.
These transformers support both metering (e.g., 0.2S, 0.5) and protection (e.g., 10P10) accuracy classes, making them suitable for energy metering, relay protection, and SCADA integration in 6–10 kV switchgear. They comply with IEC 61869-1/2 and GB/T 20840.1/2 standards, and operate at 50 Hz (60 Hz available on request).
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| System voltage class | 10 kV |
| Rated frequency | 50 Hz (60 Hz optional) |
| Rated secondary current | 1 A or 5 A |
| Accuracy classes | Metering: 0.2S, 0.5; Protection: 10P10 (as specified) |
| Rated burden | As per core specification (VA) |
| Burden power factor | cosφ = 0.8 (lagging) |
| Short-circuit withstand | Ith (1 s) and Idyn (peak) per order |
| Insulation level | Per IEC/GB standards and project requirements |
| Applicable standards | IEC 61869-1/2; GB/T 20840.1/2; GB 1208-1997 |
Model Designation
- L: Current transformer (CT)
- Z: Indoor support (pillar) type
- Z: Cast-resin (epoxy) insulated, fully enclosed structure
- B: Protection configuration available (metering/protection application)
- J: Reinforced design
- 9: Design code (platform/iteration)
- 10: Voltage class (kV)
- A / B / C: Mechanical variant code (installation/structure differences)
Construction
The LZZBJ9-10 series features a post-type (support) mechanical design optimized for compact installation in indoor switchgear. Its core is ring-type, with primary conductor passing through the center aperture and secondary windings uniformly wound around the magnetic core. The entire assembly is encapsulated in a single-piece epoxy resin cast structure, providing excellent electrical insulation, mechanical rigidity, and resistance to environmental factors such as humidity and contamination. This fully enclosed construction ensures consistent performance over time under standard indoor service conditions.
Technical Parameters
Service Conditions
- Installation environment: Indoor installation only
- Altitude: Not exceeding 1000 m above sea level (higher altitude shall be specified for engineering confirmation)
- Ambient temperature: −5 °C to +40 °C
- Relative humidity: Daily average ≤ 95%, monthly average ≤ 90% (at +20 °C reference)
- Environmental conditions: Free from corrosive gases or vapors; free from explosive or flammable media; no severe vibration, mechanical shock, or impact
Technical Parameters
The LZZBJ9-10 A/B/C series is a 10 kV indoor cast-resin current transformer designed for 50 Hz AC power systems. It features an ambient operating temperature range of −5 °C to +40 °C, suitability for altitudes up to 1000 m, and compliance with standard technical specifications for accuracy, burden, and short-circuit withstand capability. Primary current ratings span from 5 A to 2000 A with multiple accuracy class combinations for metering and protection applications.
Current Transformer Data
| Rated Primary Current (A) |
Accuracy Class (Protection/ Measurement) |
Rated Output (VA) |
Short-Time Thermal Current |
Dynamic Current |
|---|---|---|---|---|
| 5–100 | 0.2S / 10P10 | 10 / 15 | 150 × In | 375 × 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 0.2S / 0.5 / 10P10 0.5 / 10P10 0.2 / 10P10 |
10 / 15 10 / 10 / 15 10 / 15 10 / 15 |
63 kA | 130 kA |
| 1000 | 0.2S / 10P10 0.2S / 0.5 / 10P10 0.5 / 10P10 0.2 / 10P10 |
10 / 15 10 / 10 / 15 10 / 15 10 / 15 |
80 kA | 160 kA |
| 1200 | 0.2S / 10P10 0.2S / 0.5 / 10P10 0.5 / 10P10 0.2 / 10P10 |
10 / 15 10 / 10 / 15 10 / 15 10 / 15 |
80 kA | 160 kA |
| 1500 | 0.2S / 10P10 0.2S / 0.5 / 10P10 |
10 / 15 10 / 10 / 15 |
100 kA | 160 kA |
| 2000 | 0.5 / 10P10 0.2 / 10P10 |
10 / 15 10 / 15 |
100 kA | 160 kA |
Installation & Wiring
Installation Diagram
The LZZBJ9-10 A, B, and C current transformers are installed indoors using the provided fixing holes on the base. Mounting must ensure mechanical stability and alignment with primary conductors. Primary connections are made either via bolted terminals or directly to a busbar, depending on the specific variant. Maintain adequate electrical clearance around the unit for insulation integrity, heat dissipation, and safe maintenance access as shown in the dimensional drawings.
Selection & FAQs
Selection Guide
- Choose A, B or C from the approved mechanical drawing. These suffixes identify installation and structural differences, so compare primary connection, aperture, body size, mounting pattern and terminal orientation.
- Select the primary ratio from 5A–2000A. Match continuous load and metering range, then verify the exact row’s 1-second thermal and peak dynamic withstand against the system fault study.
- Define two- or three-core duty. Standard configurations pair measurement with 10P10 protection; selected 150A–200A and 800A–1500A versions also list 0.2S/0.5/10P10 three-core arrangements.
- Confirm 1A or 5A secondary and per-core burden. Calculate connected devices, cable resistance, terminals and test equipment, and ensure every core remains within its 10VA or 15VA rating.
- Complete the dielectric and environmental specification. Obtain the full insulation level, partial-discharge limit, creepage, altitude correction, frequency, dimensions and current IEC 61869 test documentation.
Frequently Asked Questions
Q1: Are these cast-resin current transformers suitable for outdoor installation?
No, they are strictly for indoor installation only. The design requires an environment free from corrosive gases, explosive media, and severe vibration. Contact our engineering team for outdoor alternatives.
Q2: What is the short-circuit withstand capability for 100A models?
The 5–100A rated models withstand a short-time thermal current of 150 × In and a dynamic current of 375 × In. Verify your specific fault level requirements with our technical department.
Q3: Which accuracy classes are available for protection and metering?
The standard configuration offers 0.2S for measurement and 10P10 for protection, with rated outputs of 10 VA and 15 VA respectively. Specify your exact burden requirements during the inquiry process.
Q4: How do we order these for altitudes above 1000 meters?
Standard units are rated for altitudes not exceeding 1000 m above sea level. For higher elevations, specify the exact altitude during inquiry for engineering confirmation and custom design adjustments.
Q5: Can you provide factory test certificates before delivery?
Routine tests verify accuracy, burden, and short-circuit withstand capabilities per standard technical specifications. Request detailed test reports and compliance documentation from our sales team prior to finalizing your order.
Q6: When should we specify custom primary current ratings?
Custom primary current ratings between 5 A and 2000 A are required when standard catalog sizes do not match your load profile. Submit your single-line diagram for precise factory selection.