Overview
The LZZJ-10, LZZJ-12Q, and LZZ(B)J1-10 are indoor epoxy cast-resin current transformers designed for 10kV, 11kV, and 12kV medium-voltage AC systems. These fully enclosed, post-type devices feature a solid epoxy resin insulated body that encapsulates the magnetic core and secondary winding, ensuring high dielectric strength and mechanical robustness for indoor applications.
They support accuracy classes such as 0.2S, 0.5, 1, and 10P10 for both metering and protection functions, making them suitable for energy metering, feeder monitoring, relay protection, and SCADA integration in fixed switchgear, incoming/outgoing panels, and distribution automation systems. The design complies with standard insulation levels of 12/42/75kV and operates at 50Hz.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 10kV, 11kV, 12kV |
| Rated insulation level | 12/42/75kV |
| Rated frequency | 50Hz |
| Secondary current | 5A or 1A |
| Phase | Single phase |
| Insulation material | Epoxy cast-resin |
| Accuracy classes (measurement) | 0.2S, 0.5, 1 |
| Accuracy class (protection) | 10P10 |
| Installation type | Indoor post-type / busbar |
| Structure | Fully enclosed, cast-resin, post-type |
| Primary connection | Top terminal for bolted busbar |
| Applications | Metering, protection, monitoring |
Model Designation
- L: Current transformer
- Z: Indoor type
- Z: Epoxy resin cast insulation / fully enclosed structure
- B: Protection class available (for models with dual cores)
- J: Reinforced or enhanced design
- 1 / 2: Design sequence or structure series code
- 10 / 12: 10kV catalogue code or 12kV international insulation class
- Q: Enhanced insulation variant in certain catalogues
Construction
The LZZJ-10, LZZJ-12Q, and LZZ(B)J1-10 current transformers feature a monolithic epoxy cast-resin construction, providing a fully enclosed, maintenance-free structure. The magnetic core and secondary winding are completely embedded within the high-strength epoxy resin body, which offers excellent electrical insulation, moisture resistance, and thermal stability. The primary conductor passes through the center of the post-type housing, with primary terminals located on the top surface for secure bolted connection to indoor busbars. This compact, rigid design ensures reliable performance in fixed switchgear installations while maintaining consistent secondary signal accuracy under normal and fault conditions.
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 applications: for high altitude, humid, coastal or special switchgear applications, technical confirmation is required before ordering.
Technical Parameters
The LZZJ-10, LZZJ-12Q, and LZZ(B)J1-10 are epoxy cast-resin current transformers designed for indoor use in 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 5A to 1500A (reference), with secondary options of 5A or 1A.
| Rated primary current (A) |
Rated Output (VA) |
Short-time thermal current |
Rated dynamic current (kA) |
||
|---|---|---|---|---|---|
| 0.5 | 10P10 | kA (rms) | S | ||
| 5 | 10 | 15 | 0.5 | 2 | 1.25 |
| 10 | 1 | 2.5 | |||
| 15 | 1.5 | 3.75 | |||
| 20 | 2 | 5 | |||
| 30 | 3 | 7.5 | |||
| 40 | 4 | 10 | |||
| 50 | 5 | 12.5 | |||
| 75 | 8 | 20 | |||
| 100 | 10 | 25 | |||
| Rated primary current (A) |
Rated Output (VA) |
Short-time thermal current |
Rated dynamic current (kA) |
||
|---|---|---|---|---|---|
| 0.5 | 10P10 | kA (rms) | S | ||
| 150 | 10 | 15 | 16 | 2 | 40 |
| 200 | 10 | 20 | 4 | 50 | |
| 300 | 20 | 50 | |||
| 400 | 20 | 50 | |||
| 500 | 15 | 25 | 63 | ||
| 600 | 15 | 25 | 63 | ||
| 800 | 15 | 32 | 80 | ||
| 1000 | 20 | 25 | 32 | 80 | |
Installation & Wiring
Installation Diagram
The LZZJ-10, LZZJ-12Q, and LZZ(B)J1-10 current transformers feature a compact post-type design intended for secure mounting within indoor switchgear. Installation is achieved via base mounting holes aligned with the switchgear structure, with primary terminals positioned at the top for busbar connection and secondary terminals located at the bottom for external wiring.
Selection & FAQs
Selection Guide
- Confirm a 10kV–12kV, 50Hz indoor system requiring the 12/42/75kV insulation level and a post-type bolted-busbar interface.
- Select single or double ratio from operating current, future load, metering resolution and fault level; verify tap connections for every intended ratio.
- Assign 0.2S, 0.5 or class 1 cores to measurement and 10P10 cores to protection, with the required number of independent secondaries.
- Choose 1A or 5A and calculate meter/relay plus lead burden before specifying 10VA, 15VA, 20VA or 25VA output.
- Confirm short-time thermal and dynamic ratings, P1/P2 direction, busbar forces, mounting footprint, phase clearance and −5°C to +55°C environment.
Frequently Asked Questions
Q1: Are these epoxy cast-resin current transformers suitable for outdoor installation?
No, they are strictly designed for indoor medium-voltage switchgear. The environment must be free from severe vibration, conductive dust, and corrosive gases. Contact us for outdoor alternatives.
Q2: What is the maximum ambient temperature for continuous operation?
The maximum ambient temperature is +55°C, with a minimum of -5°C. They operate at a rated frequency of 50Hz. Confirm specific thermal limits for high-altitude applications.
Q3: Which accuracy classes are available for the secondary windings?
Standard accuracy classes include 0.5 for measurement and 10P10 for protection. Secondary current options are 5A or 1A. Specify your exact accuracy and ratio requirements during inquiry.
Q4: Which international standards do these current transformers comply with?
They comply with GB1208-2006 and IEC 60044-1:2003 standards. Rated outputs are 10VA for 0.5 class and 15VA for 10P10. Request specific type test reports from our sales team.
Q5: Can the primary current rating be customized beyond 1500A?
The standard primary current range is 5A to 1500A. Custom ratios and specific short-time thermal currents are subject to technical confirmation. Contact our engineering team to discuss non-standard requirements.
Q6: Where are the LZZJ-12Q current transformers typically applied?
They are applied in indoor 10kV to 12kV switchgear. They operate at 50Hz in clean environments free from conductive dust. Check technical datasheets for specific switchgear compatibility details.