Overview
The LFZD-0.66 / LMZ□D-0.66 State Grid Metering Current Transformer is a low-voltage, indoor current transformer designed for accurate current measurement and electrical energy metering in AC systems up to 0.66kV at 50Hz. It is commonly installed in grid metering cabinets, distribution panels, metering boxes, and low-voltage monitoring circuits, providing reliable performance for utility and industrial applications.
Built with an unsaturated resin cast structure and fixed mounting, this series supports both round-hole and rectangular-window configurations to accommodate varying conductor layouts and primary current ranges. It delivers a standardized secondary output of either 5A or 1A, ensuring compatibility with energy meters, measuring instruments, and other metering equipment used in modern low-voltage power systems.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Rated voltage | 0.66kV and below |
| Rated frequency | 50Hz |
| Secondary current | 5A or 1A |
| Installation type | Indoor, fixed |
| Insulation material | Unsaturated resin cast |
| Application | Metering and current measurement |
| Primary conductor type | Cable or busbar |
| Accuracy class | Metering grade (e.g., 0.2S, 0.5S) |
Model Designation
- LFZD: Low-voltage cast-resin metering current transformer series
- LMZ□D: Low-voltage busbar/window-type metering current transformer series with design code
- 0.66: Rated voltage class of 0.66kV
- D: Dedicated metering application design code
- 30, 40, 60, 80, etc.: Structural or window size code based on model variant
Construction
The LFZD-0.66 and LMZ□D-0.66 transformers feature a robust unsaturated resin cast structure, offering excellent electrical insulation, mechanical strength, and resistance to environmental factors. The core and windings are fully encapsulated in cast-resin, ensuring long-term stability and protection against moisture and contamination. The fixed-installation design allows secure mounting in metering cabinets and distribution panels. Depending on the model, the unit includes either a round hole or rectangular window to accommodate cables or busbars, enabling flexible integration into various low-voltage metering setups.
Technical Parameters
Service Conditions
- Installation location: indoor
- System voltage: 0.66kV and below
- Rated frequency: 50Hz
- Ambient temperature: -5°C to +40°C
- Environmental requirements: The installation environment should be free from severe vibration, conductive dust, corrosive gas, explosive medium, and heavy pollution.
- Special conditions: For special altitude, humidity, pollution level, metering box layout, or installation space requirements, technical confirmation is recommended before ordering.
Technical Data
The LFZ1D-0.66 and LMZ□D-0.66 current transformers are designed for indoor metering applications in systems up to 0.66kV, featuring cast-resin insulation and compliance with major international standards.
| Rated Primary Current (A) |
Rated Secondary Current (A) |
Accuracy Class |
Rated Output (VA) |
|---|---|---|---|
| 5, 10, 15, 20, 30, 40, 50, 75, 100 | 5 / 1 | 0.2 / 0.2S / 0.5 / 0.5S | 2.5 / 5 / 10 |
| 150, 200, 250, 300, 400, 500 | 5 / 1 | 0.2 / 0.2S / 0.5 / 0.5S | 5 / 10 / 15 |
| 600, 800, 1000, 1200, 1500 | 5 / 1 | 0.2 / 0.2S / 0.5 / 0.5S | 10 / 15 / 20 |
Installation & Wiring
Outline Dimensions
All models feature cast-resin construction with either round-hole or rectangular-window designs. Dimensions vary by model type (e.g., LFZD-0.66-30, LMZ□D-0.66-80) and are provided in millimeters. Confirm exact dimensions from the approved outline drawing before installation or ordering.
Selection & FAQs
Selection Guide
- Select the 5A–1500A primary ratio from normal load, maximum demand, and metering range.
- Choose a 1A or 5A secondary that matches the meter input and secondary cable distance.
- Specify the required 0.2, 0.2S, 0.5, or 0.5S class and calculate the total VA burden.
- Select LFZD or LMZ□D and a round or rectangular window from conductor dimensions and panel layout.
- Confirm rated output, approved dimensions, polarity, sealing requirements, grounding, and indoor conditions.
Frequently Asked Questions
Q1: Which accuracy class is best for revenue metering?
Select 0.2S or 0.5S classes for revenue billing. These ensure high precision across varying load currents up to 1500A primary. Contact us for specific calibration certificates.
Q2: Can these transformers be installed in outdoor environments?
No, they are strictly designed for indoor installation only. The environment must remain free from severe vibration, conductive dust, and corrosive gases. Standard models operate safely between -5°C and +40°C.
Q3: What is the maximum rated primary current available?
The maximum rated primary current is 1500A. Standard secondary currents are 5A or 1A with rated outputs up to 20VA. Please specify your exact current ratio during inquiry.
Q4: How to order for high altitude or humid locations?
Standard models suit normal environmental conditions up to 0.66kV. For special altitude, high humidity, or unique metering box layouts, technical confirmation is required before ordering. Custom designs are subject to factory engineering review.
Q5: Are these current transformers compliant with international standards?
Yes, they feature cast-resin insulation and comply with major international standards for 0.66kV systems. Specific test reports and compliance certificates are provided upon request. Contact us to verify your project requirements.
Q6: Where can the LFZD-0.66 current transformers be applied?
They are ideal for indoor metering applications in low-voltage systems up to 0.66kV. Available in multiple frame sizes to accommodate different primary current ratings from 5A to 1500A. The 50Hz rated frequency ensures stable grid integration.