Overview
The LFZ1D-0.66 low-voltage state grid metering current transformer is an indoor, unsaturated cast-resin current transformer designed for accurate current measurement and electrical energy metering in AC systems up to 0.66kV at 50Hz. It provides galvanic isolation between high-current primary circuits and secondary metering or monitoring equipment, ensuring safe and reliable signal transmission for utility-grade applications.
This series is commonly installed in low-voltage metering cabinets, distribution panels, grid metering boxes, and energy measurement circuits. Featuring a compact, fixed-mount cast-resin insulated structure, the LFZ1D-0.66 delivers stable measurement accuracy under typical indoor operating conditions while meeting space constraints in modern metering installations.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Rated voltage | 0.66kV and below |
| Rated frequency | 50Hz |
| Rated secondary current | 5A |
| Installation type | Indoor, fixed |
| Insulation type | Cast-resin |
| Accuracy classes | 0.5S, 0.2S (depending on ratio) |
| Primary current range | As per standard ratios (e.g., 100/5, 200/5, etc.) |
| Application | State grid metering, energy measurement |
Model Designation
- LFZ1D: Low-voltage cast-resin metering current transformer series
- 0.66: Rated voltage class of 0.66kV
- D: Dedicated metering application design code
Construction
The LFZ1D-0.66 features a robust indoor cast-resin insulated body with an unsaturated magnetic core, optimized for stable performance in low-voltage metering environments. The entire assembly is encapsulated in flame-retardant epoxy resin, providing excellent dielectric strength, mechanical durability, and resistance to environmental factors such as humidity and dust. The fixed-installation design includes pre-molded mounting feet or flanges for secure integration into metering cabinets and distribution panels. All conductive parts are fully embedded within the resin matrix, ensuring operator safety and long-term reliability under continuous operation at 50Hz.
Technical Parameters
Service Conditions
- Installation location: indoor
- System voltage: 0.66kV and below
- Rated frequency: 50Hz
- Ambient temperature: -5°C to +40°C
- Relative humidity: not more than 80%
- Altitude: not more than 1000m unless otherwise specified
- Environmental restrictions: The installation environment should be free from metal dust, severe vibration, conductive dust, corrosive gas, explosive medium, and heavy pollution.
- Special requirements: For special altitude, humidity, metering cabinet layout, or installation space requirements, technical confirmation is recommended before ordering.
Technical Data
The LFZ1D-0.66 low-voltage current transformer is designed for indoor metering applications in compliance with relevant national and grid standards, offering high accuracy and reliable performance under standard service conditions.
| Model | Rated Primary Current (A) |
Rated Secondary Current (A) |
Rated Burden 0.5S (VA) |
Rated Burden 0.2S (VA) |
|---|---|---|---|---|
| LFZ1D-0.66 | 10, 15, 20, 25, 30, 40, 50, 60, 75, 100 | 5 | 5 / 2.5 | 5 / 2.5 |
Installation & Wiring
Outline Dimensions
The LFZ1D-0.66 current transformer features a compact cast-resin housing designed for fixed mounting in low-voltage metering cabinets and distribution panels. Key dimensions include a length (L) of 100 mm and width (W) of 118 mm. The height (H) varies depending on the specific configuration and must be confirmed against the approved outline drawing prior to installation or ordering. Ensure adequate clearance within the cabinet for primary conductor routing, secondary terminal access, and ventilation.
Wiring Diagram
Connect the secondary terminals according to the polarity markings: S1 denotes the non-inverting (positive) terminal and S2 the inverting (negative) terminal. Wiring must follow the project-specific schematic and align with the energy meter’s input requirements. The secondary circuit must always form a closed loop through the connected metering device—never leave it open when the primary conductor is energized. Proper grounding of the CT case and secondary circuit shielding (if applicable) should comply with local electrical codes and metering authority specifications.
Selection & FAQs
Selection Guide
- Select the 10/5A–100/5A ratio from the circuit’s normal load and maximum demand.
- Choose class 0.2S or 0.5S according to the metering authority and accuracy requirement.
- Calculate the meter and cable-loop burden and confirm whether 2.5VA or 5VA is required.
- Verify the fixed mounting dimensions, conductor routing, and terminal access in the metering cabinet.
- Confirm polarity, sealing provisions, secondary grounding, environmental limits, and required test documentation.
Frequently Asked Questions
Q1: Is the LFZ1D-0.66 current transformer suitable for outdoor installation?
No, it is strictly designed for indoor applications. The installation environment must remain free from corrosive gases and conductive dust. Contact our team for outdoor-rated alternatives.
Q2: Which accuracy class is recommended for revenue metering applications?
The 0.2S accuracy class is recommended for revenue billing. It provides a rated burden of 5 VA or 2.5 VA at 50Hz. Specify your exact metering requirements during ordering.
Q3: What are the available rated primary current options?
Standard primary current ratings range from 10A to 100A in fixed increments. The rated secondary current is fixed at 5A for all models. Confirm your specific primary current needs with our engineering team.
Q4: Can this transformer operate at altitudes above 1000 meters?
Standard models are rated for altitudes up to 1000m. For higher elevations, special technical confirmation and design adjustments are required. Please provide your exact site elevation to our sales team.
Q5: Are factory test reports provided before shipment?
Test documentation is subject to confirmation based on your order. Standard routine tests apply per national grid standards. Contact our procurement department for detailed compliance records.
Q6: Where is this low-voltage current transformer typically applied?
This model is primarily used for indoor electrical metering in systems up to 0.66kV. It ensures high accuracy for 50Hz power distribution networks. Request our product catalog for more manufacturer details.
Q7: How does ambient temperature affect the installation requirements?
Operation is guaranteed within an ambient temperature range of -5°C to +40°C. Relative humidity must not exceed 80% during installation. Verify your local climate conditions with our technical support.