Overview
The LMZB3-10Q/137 is an indoor single-phase epoxy cast-resin current transformer designed for 10kV, 11kV, and 12kV class medium-voltage AC systems operating at 50Hz or 60Hz. It features a fully enclosed epoxy resin cast structure with a hollow through-window aperture, enabling the primary conductor—cable, copper bar, or busbar—to pass directly through the unit.
With rated primary currents from 1500A to 5000A and secondary outputs of 5A or 1A, it supports combined metering and protection accuracy classes such as 0.2/5P10, 0.5/5P15, and 5P20/5P20. The transformer is suitable for current measurement, energy metering, feeder monitoring, and relay protection in indoor switchgear applications, complying with standard insulation levels of 12/42/75kV and a surface creepage distance of 240mm.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 10kV / 11kV / 12kV |
| Insulation level | 12/42/75kV |
| Rated frequency | 50Hz or 60Hz |
| Primary current | 1500A – 5000A |
| Secondary current | 5A or 1A |
| Metering accuracy | 0.2, 0.5 |
| Protection accuracy | 5P10, 5P15, 5P20 |
| Creepage distance | 240mm |
| Phase | Single-phase |
| Installation | Indoor |
| Insulation material | Epoxy cast-resin |
| Application | Measurement, metering, protection |
Construction
The LMZB3-10Q/137 employs a fully enclosed epoxy cast-resin body with a central hollow aperture, allowing the primary conductor to pass through without electrical contact. The ring core and secondary winding are completely encapsulated within the resin matrix, providing robust mechanical support, high dielectric strength, and stable thermal performance under continuous load. The cylindrical housing includes a square mounting base for secure installation in indoor switchgear cabinets. Secondary terminals are integrated into a terminal block area on the resin body, facilitating reliable connections to meters, relays, and monitoring equipment. The design ensures compliance with required creepage distances and insulation coordination for 10kV-class indoor environments.
Technical Parameters
Service Conditions
- Installation location: indoor medium-voltage switchgear
- Rated voltage: 10kV, 11kV and 12kV class systems by project confirmation
- Rated frequency: 50Hz or 60Hz
- Ambient temperature: -5°C to +40°C
- Installation environment: should be free from severe vibration, corrosive gas, explosive medium, conductive dust, heavy pollution and abnormal condensation.
- Special service conditions: for high altitude, coastal, humid or heavy-pollution service conditions, technical confirmation is recommended before ordering.
Technical Parameters
The LMZB3-10Q/137 is a cast-resin insulated current transformer designed for indoor use in 10kV class systems (suitable for 10kV, 11kV, and 12kV applications upon project confirmation). It operates within an ambient temperature range of -5°C to +40°C, complies with GB20840.2-2014 and IEC61869-2:2003 standards, and supports primary currents from 1500A to 5000A with secondary outputs of 1A or 5A.
| Rated Primary Current (A) |
Accuracy Classes Combination |
Rated Secondary Output (VA) |
Surface
Creepage |
|---|---|---|---|
| 1S/2S | |||
| 1500~2500 | 0.2/5P10 | 30/75 | 240 mm |
| 0.5/5P10 | 50/75 | ||
| 0.2/5P15 | 30/50 | ||
| 0.5/5P15 | 50/50 | ||
| 0.2/5P20 | 30/30 | ||
| 0.5/5P20 | 50/30 | ||
| 5P10/5P10 | 75/75 | ||
| 5P15/5P15 | 50/50 | ||
| 5P20/5P20 | 30/30 | ||
| 3000~4000 | 0.2/5P10 | 40/80 | |
| 0.5/5P10 | 60/80 | ||
| 0.2/5P15 | 40/60 | ||
| 0.5/5P15 | 60/60 | ||
| 0.2/5P20 | 40/40 | ||
| 0.5/5P20 | 60/40 | ||
| 5P10/5P10 | 80/80 | ||
| 5P15/5P15 | 60/60 | ||
| 5P20/5P20 | 40/40 | ||
| 5000 | 0.2/5P10 | 40/75 | |
| 0.5/5P10 | 60/75 | ||
| 0.2/5P15 | 40/50 | ||
| 0.5/5P15 | 60/50 | ||
| 0.2/5P20 | 40/30 | ||
| 0.5/5P20 | 60/30 | ||
| 5P10/5P10 | 75/75 | ||
| 5P15/5P15 | 50/50 | ||
| 5P20/5P20 | 30/30 |
Installation & Wiring
Installation Diagram
This current transformer is installed by mounting it through a switchgear wall or panel, with the primary cable or busbar passing through the central Ø137 aperture. The mounting plate must be securely fastened using the specified hole pattern, and adequate clearance must be maintained around the unit for insulation, creepage distance (minimum 240mm), and terminal accessibility.
Selection & FAQs
Selection Guide
- Confirm the insulated conductor fits the nominal Ø137 aperture and that the 350mm body, Ø268 outline and mounting plate fit the panel.
- Select a 1500A–2500A, 3000A–4000A or 5000A ratio group from continuous-current and fault-duty studies.
- Choose 1A or 5A and specify either 0.2/0.5 measurement plus 5P protection or two independent matching 5P cores.
- Calculate both secondary burdens and select the exact paired 30VA–80VA output for 5P10, 5P15 or 5P20.
- Verify 240mm creepage, four-Ø14 mounting, conductor support, grounding, shorting blocks and the correct IEC 61869-2 edition.
Frequently Asked Questions
Q1: Can this epoxy cast-resin CT be applied in 12kV switchgear?
Yes, subject to project confirmation. The LMZB3-10Q/137 is rated for 10kV, 11kV, and 12kV indoor medium-voltage systems. Please specify your exact system voltage for factory verification.
Q2: When is technical confirmation required for special environments?
Technical confirmation is required for high altitude, coastal, or heavy-pollution conditions. The standard ambient temperature range is -5°C to +40°C. Ensure the environment is free from corrosive gases and conductive dust.
Q3: Which primary current ratings are available for this model?
This model supports primary currents ranging from 1500A to 5000A. Secondary outputs are available in 1A or 5A configurations. Specify your exact primary and secondary requirements during ordering.
Q4: Does this current transformer comply with IEC61869-2 standards?
Yes, it fully complies with IEC61869-2:2003 and GB20840.2-2014 standards. It is designed for 50Hz or 60Hz rated frequencies. Contact our technical team for detailed compliance documentation.
Q5: How do I order this transformer for coastal environments?
Special service conditions like coastal or high-altitude environments require technical confirmation. Please specify your exact environmental parameters before ordering. Contact our engineering team for project-specific adjustments.
Q6: Is this manufacturer a supplier of medium-voltage switchgear components?
Yes, we manufacture epoxy cast-resin current transformers for indoor medium-voltage switchgear applications. The LMZB3-10Q/137 is specifically engineered for 10kV class power distribution systems. Contact us for OEM or bulk inquiries.
Q7: How do I select the correct accuracy class combination?
Accuracy class combinations depend on your specific metering or protection needs. Confirm your 1S/2S core requirements and rated secondary output (VA) with our technical support team.