Overview
The LMZ-10 and LMZJ1-10 are indoor wall-through busbar-type current transformers with epoxy resin cast insulation, designed for 10kV, 11kV, and 12kV medium-voltage AC systems operating at 50Hz. These devices feature a through-busbar structure where the primary conductor passes centrally through the transformer body, enabling direct integration into switchgear and distribution cabinets.
They support standard 5A secondary output and offer accuracy combinations such as 0.5/3, 0.5/10P, or 0.5/0.5 to meet requirements for metering, relay protection, and current monitoring. Suitable for use in industrial and utility indoor installations, these CTs comply with relevant IEC and national standards for medium-voltage current transformers.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 10kV / 11kV / 12kV |
| Rated frequency | 50Hz |
| Rated secondary current | 5A |
| Insulation type | Epoxy resin cast |
| Primary configuration | Busbar-through type |
| Accuracy classes | 0.5 (metering), 3 / 10P (protection) |
| Installation environment | Indoor |
| Application | Measurement, energy metering, relay protection |
Model Designation
- L: Current transformer
- M: Busbar-type / bus-type structure
- Z: Epoxy resin casting insulation
- J1: Extended output / reinforced design series
- 10: Rated voltage class: 10kV
Construction
The LMZ-10 and LMZJ1-10 current transformers feature a robust wall-through busbar-type construction. The primary conductor passes through the central aperture of the unit, while the secondary windings are wound on a high-permeability iron core and fully encapsulated in epoxy resin. This cast-resin insulation provides excellent dielectric strength, mechanical stability, and resistance to environmental factors in indoor applications. The housing integrates a mounting plate, earthing bolt, rating plate, and pre-drilled installation holes for secure and straightforward assembly into switchgear panels. The compact, sealed design ensures reliable performance under continuous operation in medium-voltage distribution environments.
Technical Parameters
Service Conditions
- Installation location: indoor medium-voltage switchgear
- Altitude: not over 1000m unless otherwise specified
- Ambient temperature: -5°C to +40°C
- Relative humidity: less than 85% at 20°C reference condition
- Environmental conditions: The product should be installed in a site free from severe vibration, corrosive gas, explosive medium, conductive dust, heavy pollution and abnormal condensation.
- Vibration resistance: The product has passed vibration test conditions equivalent to 0.4g three-sine waves under reference requirements.
Technical Parameters
The LMZ-10 and LMZJ1-10 are wall-through busbar-type cast-resin current transformers designed for indoor 10kV class systems (including 10kV, 11kV, and 12kV). They feature epoxy resin casting insulation, operate within an ambient temperature range of -5°C to +40°C, and are suitable for installations up to 1000m altitude. Compliant with IEC standards and GB1208-87, these units support primary currents from 300A to 5000A with various accuracy and burden combinations.
| Type | Rated Voltage (kV) |
Rated Primary Current (A) |
Rated Secondary Current (A) |
Accuracy Classes |
Rated Secondary
Burden (VA) |
Accuracy Limit Factor for 10P |
||
|---|---|---|---|---|---|---|---|---|
| Class 0.5 |
Class 3 |
Class 10P |
||||||
| LMZ-10 | 10 | 300-1000 | 5 | 0.5/3 0.5/10P |
10 | 15 | 15 | 10 |
| LMZJ1-10 | 10 | 1500 | 5 | 0.5/10P | 40 | 80 | 15 | |
| 2000, 3000, 4000, 5000 |
60 | 100 | ||||||
| Type | Rated Primary Current (A) |
Accuracy Classes |
L (mm) |
C (mm) |
D (mm) |
d (mm) |
A1 (mm) |
A2 (mm) |
B1 (mm) |
B2 (mm) |
Weight (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| LMZ-10 | 300 | 0.5/3 0.5/10P |
220 | 125 | 136 | 33 | 140 | 170 | 206 | 236 | 7.5 |
| 400 | 43 | ||||||||||
| 500-600 | 145 | 53 | |||||||||
| 750-800 | 63 | ||||||||||
| 1000 | 225 | 132 | 173 | 85 | 165 | 195 | 230 | 260 | 8.2 | ||
| LMZJ1-10 | 1500-2000 | 0.5/10P | 276 | 173 | 240 | 128 | 256 | 296 | 346 | 346 | 25.8 |
| 3000 | 177 | 256 | 143 | ||||||||
| 4000 | 168 | 305 | 170 | 300 | 340 | 420 | 420 | 26.5 | |||
| 5000 |
Installation & Wiring
Installation Diagram
The LMZ-10 and LMZJ1-10 current transformers are designed for indoor wall-through busbar installation. The primary busbar passes through the central aperture, and the unit is secured to the switchgear panel via the mounting plate with pre-defined hole positions. Ensure alignment with the approved switchgear layout drawing before final installation.
Selection & FAQs
Selection Guide
- Choose the model from the certified ratio and dimensional schedule. The source data indicates LMZ-10 for standard feeder currents and LMZJ1-10 for the upper-current range, but the exact transition between the two models should be confirmed against the current factory drawing.
- Match the primary ratio to the maximum continuous load. Available primary ratings span 300A to 5000A with a fixed 5A secondary; also check short-time current requirements and the connected instrument range.
- Select the core combination by function. Use 0.5/0.5 or 0.5/3 where two measurement duties are required, and 0.5/10P where one core supplies metering and the other supplies protection.
- Verify each core’s rated output and protection factor. Outputs vary from 10VA to 100VA by ratio and core; for 10P protection cores, confirm whether the required accuracy limit factor is 10 or 15 from the final schedule.
- Check the complete mechanical and insulation interface. Confirm busbar size, aperture clearance, panel cutout, mounting-hole pattern, terminal arrangement, system insulation level, altitude and ambient conditions before ordering.
Frequently Asked Questions
Q1: Can this wall-through CT be installed in 11kV or 12kV switchgear?
Yes, it is designed for 10kV class systems, including 10kV, 11kV, and 12kV indoor medium-voltage switchgear. Specify your exact system voltage during inquiry for factory verification.
Q2: What are the ambient temperature and altitude limits for installation?
Standard limits are -5°C to +40°C with a maximum altitude of 1000m. For installations exceeding these conditions, please contact our engineering team for customized design confirmation.
Q3: Which accuracy classes are available for these cast-resin current transformers?
Standard models support various accuracy and burden combinations for 300A to 5000A primary currents. Contact us with your specific metering requirements to confirm available accuracy classes.
Q4: Are these transformers compliant with international IEC standards?
Yes, the LMZ-10 and LMZJ1-10 models are fully compliant with IEC standards and GB1208-87. Request the specific test certificates and compliance documents from our sales team before ordering.
Q5: How are these units tested before factory shipment?
Routine tests include a vibration test equivalent to 0.4g three-sine waves under reference requirements. Detailed factory test reports and specific parameters are provided upon request.
Q6: What type of current transformer is the LMZ-10 model?
It is a wall-through busbar-type cast-resin current transformer for indoor medium-voltage applications. The epoxy resin casting provides reliable insulation for 10kV class systems. Contact us for detailed insulation specifications.