Overview
The LZZ(B)J2-10 / LZZBJ2-12 is an indoor post-type epoxy cast-resin current transformer designed for 10kV, 11kV, and 12kV class medium-voltage AC systems. It features a full-enclosed, support-type structure with epoxy resin insulation, providing high dielectric strength and mechanical robustness for indoor switchgear applications.
This transformer supports both metering and protection functions, offering accuracy classes such as 0.2, 0.5, and 10P10. It is suitable for current measurement, energy metering, feeder monitoring, and relay protection in metal-clad switchgear, incoming/outgoing panels, and distribution automation systems compliant with international standards for 12kV insulation levels.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 10kV, 11kV, 12kV |
| Rated insulation level | 12/42/75kV |
| Rated frequency | 50Hz |
| Secondary current | 5A or 1A |
| Winding configuration | Single-ratio or double-ratio |
| Metering accuracy | 0.2, 0.5 (as per IEC/ANSI) |
| Protection accuracy | 10P10 |
| Phase displacement | Within standard limits at rated burden |
| Installation type | Indoor, support-type, busbar-mounted |
| Insulation material | Epoxy cast-resin |
| Primary terminals | Top-side arrangement |
| Secondary terminals | Bottom-side arrangement |
Model Designation
- L: Current transformer
- Z: Indoor type
- Z: Epoxy resin cast insulation / fully enclosed post-type structure
- B: Protection class available
- J: Reinforced / enhanced design
- 2: Design sequence code
- 10 / 12: 10kV catalogue code / 12kV international insulation class
Construction
The LZZ(B)J2-10 / LZZBJ2-12 features a compact, post-type support structure fully encapsulated in epoxy cast-resin insulation. This construction ensures excellent electrical insulation, moisture resistance, and mechanical stability under indoor operating conditions. The primary conductor path is integrated into the upper terminal section, while the secondary terminal block is located on the lower side for easy access during switchgear wiring. The core-and-coil assembly is hermetically sealed within the resin body, isolating the high-voltage primary circuit from the low-voltage secondary circuits. This design meets the requirements for reliable operation in 12kV class systems with standard insulation levels of 12/42/75kV.
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 +55°C
- Installation environment: should be free from severe vibration, conductive dust, corrosive gas, explosive medium, heavy pollution and abnormal condensation.
- Special conditions: For high altitude, humid, coastal or special switchgear applications, technical confirmation is required before ordering.
Technical Parameters
The LZZ(B)J2-10 and LZZBJ2-12 are post-type epoxy cast-resin current transformers designed for indoor 10kV, 11kV, and 12kV systems. They operate within an ambient temperature range of -5°C to +55°C and comply with GB1208-2006 and IEC 60044-1:2003 standards. Primary current ranges from 20A to 1000A, with secondary outputs of 1A or 5A, supporting single- or double-ratio configurations.
Single Ratio Selection Table
| Rated primary current (A) |
Accuracy classed combination |
Rated Output (VA) |
Short-time thermal current (kA) |
Rated dynamic current (kA) |
|
|---|---|---|---|---|---|
| Class 1 | Class 2 | ||||
| 20 | 0.2/10P10 | 10 | 10 | 1.6/2 | 4 |
| 30 | 0.2/10P10 | 10 | 10 | 2.4/2 | 6 |
| 40 | 0.2/10P10 | 10 | 10 | 3.2/2 | 8 |
| 50 | 0.2/10P10 | 10 | 10 | 4/2 | 10 |
| 75 | 0.2/10P10 | 10 | 10 | 6/2 | 15 |
| 100 | 0.2/10P10 | 10 | 15 | 8/2 | 20 |
| 150 | 0.2/10P10 | 10 | 15 | 12/2 | 30 |
| 200 | 0.2/10P10 | 10 | 15 | 16/2 | 40 |
| 300 | 0.2/10P10 | 15 | 20 | 24/2 | 60 |
| 400 | 0.2/10P10 | 15 | 20 | 31.5/4 | 80 |
| 500 | 0.2/10P10 | 20 | 25 | 31.5/4 | 80 |
| 600 | 0.2/10P10 | 20 | 25 | 31.5/4 | 80 |
| 800 | 0.2/10P10 | 20 | 25 | 31.5/4 | 80 |
| 1000 | 0.2/10P10 | 25 | 25 | 31.5/4 | 80 |
Secondary Tap / Double Ratio Selection Table
| Rated primary current (A) |
Accuracy classed combination |
Rated Output (VA) |
Short-time thermal current (kA) |
Rated dynamic current (kA) |
|
|---|---|---|---|---|---|
| Class 1 | Class 2 | ||||
| 20-30 | 0.2/10P10 | 10 | 10 | 1.6/2 | 4 |
| 30-40 | 0.2/10P10 | 10 | 10 | 3.15/2 | 8 |
| 40-50 | 0.2/10P10 | 10 | 10 | 3.15/2 | 8 |
| 50-75 | 0.2/10P10 | 10 | 10 | 6/2 | 15 |
| 75-100 | 0.2/10P10 | 10 | 15 | 8/2 | 20 |
| 100-150 | 0.2/10P10 | 10 | 15 | 12/2 | 30 |
| 150-200 | 0.2/10P10 | 10 | 15 | 16/2 | 40 |
| 200-300 | 0.2/10P10 | 15 | 20 | 24/2 | 60 |
| 300-400 | 0.2/10P10 | 15 | 20 | 31.5/4 | 80 |
| 400-500 | 0.2/10P10 | 20 | 25 | 31.5/4 | 80 |
| 500-600 | 0.2/10P10 | 20 | 25 | 31.5/4 | 80 |
| 600-800 | 0.2/10P10 | 20 | 25 | 31.5/4 | 80 |
| 800-1000 | 0.2/10P10 | 25 | 25 | 31.5/4 | 80 |
Installation & Wiring
Installation Diagram
The LZZ(B)J2-10 and LZZBJ2-12 post-type epoxy cast-resin current transformers are designed for compact support-type installation in indoor switchgear. Mounting is achieved via four M10 holes on the base, with overall mounting dimensions as specified. Primary terminals are arranged differently based on rated primary current (I1n ≤ 1000A vs. 1200A ≤ I1n ≤ 2000A), and final layout must be verified against approved drawings prior to cabinet fabrication.
Selection & FAQs
Selection Guide
- Choose LZZ(B)J2-10 or LZZBJ2-12 from the contracted 12/42/75kV insulation, outline and panel naming convention.
- Select a 20A–1000A single ratio or a tapped double ratio that preserves metering and protection performance at both settings.
- Specify 1A or 5A and choose two or three cores using 0.2/0.5 measurement and 10P10 protection as required.
- Calculate each circuit burden and verify 10VA–25VA output plus thermal/dynamic duty at every selected ratio/tap.
- Resolve the source’s 1200A–2000A installation-layout reference before ordering; approve four-M10 mounting, busbar interface and terminals.
Frequently Asked Questions
Q1: What primary current ranges are available for this post-type CT?
Yes, multiple options are available. Primary currents range from 20A to 1000A with 1A or 5A secondary outputs, supporting single or double-ratio configurations. Contact us to specify your exact ratio requirements.
Q2: Can this current transformer be installed in high altitude or coastal areas?
Standard models require a clean environment, but special applications are possible. They must be free from severe vibration, conductive dust, and corrosive gases. For high altitude or coastal areas, technical confirmation is required before ordering.
Q3: Which accuracy class combination is suitable for protection and measurement?
The 0.2/10P10 combination is ideal for dual purposes. It provides 0.2 class accuracy for measurement and 10P10 for protection in single-ratio models. Specify your exact burden in VA during selection.
Q4: What factory tests are performed before shipping these epoxy cast-resin transformers?
Standard routine tests are always conducted per GB1208-2006 and IEC 60044-1:2003. Specific type tests or special factory acceptance protocols are subject to confirmation. Please contact our sales team for detailed test reports.
Q5: How long is the standard delivery time for customized ratios?
Lead times vary based on configuration. Standard models ship quickly, while customized single or double-ratio configurations require additional manufacturing time. Exact delivery schedules are subject to order confirmation, so contact us for current lead times.
Q6: Are these LZZBJ2-12 transformers suitable for indoor medium-voltage switchgear applications?
Yes, they are specifically designed for this purpose. These indoor post-type current transformers suit 10kV, 11kV, and 12kV medium-voltage switchgear networks. They feature epoxy cast-resin insulation for reliable indoor performance at 50Hz.
Q7: What is the maximum ambient temperature for this 10kV CT?
The maximum rated ambient temperature is +55°C. These indoor post-type current transformers operate safely within a -5°C to +55°C range. Contact our engineering team if your installation environment exceeds these standard limits.