Overview
The LMZC-0.5 is a split-core current transformer designed for indoor use in 6kV to 35kV power systems. It features an epoxy cast-resin insulation structure, providing robust mechanical strength and stable dielectric performance under typical indoor environmental conditions.
This protection-class current transformer delivers a 10P10 accuracy rating with standard outputs of 1.5VA, 3.75VA, or 5VA depending on the primary current rating. It is engineered for relay protection applications in ring network cabinets, medium-voltage switchgear, and cable termination systems where primary conductors cannot be disconnected during installation.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| System Voltage Range | 6kV – 35kV |
| Rated Frequency | 50Hz / 60Hz |
| Insulation Type | Epoxy cast-resin |
| Accuracy Class (Protection) | 10P10 |
| Rated Output | 1.5VA / 3.75VA / 5VA |
| Rated Primary Current | 50A – 400A |
| Installation Environment | Indoor |
| Core Structure | Split-core |
Model Designation
- L: Current transformer
- M: Busbar / cable through-type structure
- Z: Cast-resin insulated structure
- C: Open-type / split-core structure
- 0.5: Product design / voltage-class code used in this series
- 80 / 100 / 120: Model size code corresponding to window and outline dimensions
Construction
The LMZC-0.5 is constructed with an epoxy cast-resin body that fully encapsulates the magnetic core and secondary winding. This cast-resin insulation ensures high mechanical rigidity, excellent tracking resistance, and long-term stability in indoor environments. The split-core design allows the transformer to be opened into two halves for installation around existing insulated cables without requiring disconnection of the primary circuit. After positioning around the cable head or outlet, the two halves are reassembled and securely fastened with bolts to maintain proper magnetic coupling. A base with mounting holes enables fixed installation within ring network cabinets or switchgear compartments. The primary conductor is the cable itself, which passes through the central aperture, while the secondary winding provides a scaled-down current signal suitable for relay protection devices.
Technical Parameters
Service Conditions
- Installation location: indoor
- Applicable system: 6kV to 35kV indoor cable outlet system
- Rated frequency: 50Hz / 60Hz
- Installation environment: The installation environment should be free from severe vibration, corrosive gas, conductive dust, explosive medium, and heavy pollution.
- Cable installation: The transformer should be installed around the insulated cable head or outgoing cable according to the cabinet design.
- Split-core condition: The split-core contact surface should be clean, aligned, and fully closed before operation.
- Special requirements: For special altitude, humidity, cable diameter, cabinet layout, relay input, or burden requirements, technical confirmation is recommended before ordering.
Technical Parameters
The LMZC-0.5 series is an indoor epoxy cast-resin split-core current transformer designed for 6kV to 35kV cable outlet systems. It features a rated primary current range of 50A to 400A, operates at 50/60Hz, and complies with GB1208-2006 and IEC60044-1:2003 standards. The unit uses epoxy resin cast insulation and is suitable for standard indoor environments without extreme temperature, humidity, or contamination.
| Rated Primary Current (A) |
Accuracy Class (Protection/ Measurement) |
Rated Output (VA) |
Typical Application |
|---|---|---|---|
| 50 | 10P10 | 1.5 | Low-current cable outlet protection |
| 100 | 10P10 | 3.75 | Ring network cabinet feeder protection |
| 150 | 10P10 | 5 | Medium-voltage cable feeder protection |
| 200 | 10P10 | 5 | Switchgear outgoing line protection |
| 300 | 10P10 | 5 | Medium-load cable feeder protection |
| 400 | 10P10 | 5 | Higher-current cable outlet protection |
Installation & Wiring
Installation Diagram
The LMZC-0.5 series features a split-core design that allows installation around live or fixed cables without disconnecting them. The transformer is separated into two halves, placed around the cable head or outlet, then reassembled and secured with bolts. Mounting holes at the base enable fixed installation within switchgear or cable compartments.
Selection & FAQs
Selection Guide
- Confirm the feeder rated current, protection pickup, fault level, relay input, and required 10P10 performance.
- Select the 50A–400A primary rating and LMZC-80, LMZC-100, or LMZC-120 size for the cable and cabinet.
- Calculate relay and cable-loop burden and confirm the available 1.5VA, 3.75VA, or 5VA output.
- Verify the split-core window fits the insulated cable head without mechanical stress or clearance violation.
- Confirm clean mating faces, full bolt closure, fixed mounting, S1/S2 polarity, grounding, and secondary shorting.
Frequently Asked Questions
Q1: Is the LMZC-0.5 a zero-sequence current transformer?
The published data describes it as a protection-class phase-current CT for cable outlets, not a residual-current CT for three-phase earth-fault summation.
Q2: What systems use the LMZC-0.5?
It is designed for cable-feeder protection in indoor 6kV–35kV ring-main units and switchgear.
Q3: What primary-current ratings are available?
Standard ratings are 50A, 100A, 150A, 200A, 300A, and 400A.
Q4: What protection accuracy does it provide?
The listed accuracy class is 10P10 for overcurrent and feeder-protection applications.
Q5: What rated outputs are available?
Output is 1.5VA at 50A, 3.75VA at 100A, and typically 5VA from 150A to 400A.
Q6: Can it be installed without removing the cable?
Yes. The two core halves assemble around the existing insulated cable and bolt together.
Q7: What installation detail is most important?
The split faces must be clean, aligned, and tightly closed to preserve magnetic coupling and 10P10 performance.