What are the typical applications of this current transformer?

Typical applications include indoor low-voltage AC systems rated up to and including 0.66kV, current measurement and electrical energy metering circuits, grid metering cabinets and low-voltage metering boxes, distribution cabinets, power monitoring panels, metering terminals, industrial and commercial low-voltage power distribution systems, and busbar or cable current sensing for metering instruments and energy meters.

What are the key technical features of this product?

Key technical features include: metering-oriented design for low-voltage distribution systems; two model series (LFZD-0.66 and LMZ□D-0.66) for different conductor layouts; unsaturated resin cast insulation for performance and stability; fixed installation for metering cabinets; multiple current ranges covering small-current to high-current busbar applications; and standard secondary output of 5A or 1A.

What are the service conditions required for installation?

Service conditions include: indoor installation; system voltage of 0.66kV and below; rated frequency of 50Hz; ambient temperature from -5°C to +40°C; and an environment free from severe vibration, conductive dust, corrosive gas, explosive medium, and heavy pollution. Special requirements for altitude, humidity, pollution level, or space should be confirmed before ordering.

How do I select the correct model for my application?

Selection guidelines: 1) Confirm model series (LFZD-0.66 or LMZ□D-0.66) based on conductor form and cabinet design; 2) Confirm system voltage (≤0.66kV); 3) Select primary current based on operating current; 4) Choose secondary current (5A or 1A) per meter requirements; 5) Select accuracy class (0.2/0.2S for high precision, 0.5/0.5S for general use); 6) Ensure total burden does not exceed CT’s rated output; 7) Verify installation dimensions against cabinet clearance.

What information is needed when placing an order?

Provide: product model (LFZD-0.66 or LMZ□D-0.66); detailed structure/size code (e.g., LFZD-0.66-30); rated primary and secondary currents; accuracy class and rated output (VA); system frequency and installation environment; conductor type (busbar, cable, etc.); quantity and application; and any special requirements for sealing, labels, drawings, certificates, or packaging.

What are the installation and safety notes?

Before installation, confirm CT model, ratio, accuracy, output, and structure. Ensure conductor size matches CT window. Install via fixed mounting per approved layout. Connect secondary terminals per polarity marks (S1/S2). Never open-circuit the secondary when primary is energized. Comply with metering specs and local regulations for wiring, grounding, and sealing. Installation must be done by qualified personnel.

LFZD-0.66 / LMZ□D-0.66 Current Transformer

Product Overview

The LFZD-0.66 / LMZ□D-0.66 State Grid Metering Current Transformer, is an indoor low-voltage current transformer designed for current measurement and electrical energy metering in AC circuits with rated voltage up to and including 0.66kV and rated frequency of 50Hz. The product is commonly used in grid metering cabinets, distribution cabinets, metering boxes, and low-voltage power monitoring circuits.

This series adopts an unsaturated resin cast structure with fixed installation. According to different rated primary current ranges and conductor layouts, the product can be supplied in round-hole or rectangular-window structures. It provides a standard 5A or 1A secondary current signal for energy meters, measuring instruments, and related metering equipment.

Product Type

Item	Specification
Product name	Low Voltage Metering Current Transformer State Grid Metering Current Transformer
Model series	LFZD-0.66 / LMZ□D-0.66
Product structure	Indoor unsaturated resin cast type, fixed installation
Rated voltage class	0.66kV and below low-voltage AC system
Rated frequency	50Hz
Rated secondary current	5A or 1A
Installation location	Indoor
Typical applications	Current measurement, electrical energy metering, distribution metering, low-voltage cabinet monitoring

Product Display

Main Applications

Indoor low-voltage AC systems rated up to and including 0.66kV
Current measurement and electrical energy metering circuits
Grid metering cabinets and low-voltage metering boxes
Distribution cabinets, power monitoring panels, and metering terminals
Industrial and commercial low-voltage power distribution systems
Busbar or cable current sensing for metering instruments and energy meters

Key Technical Features

Metering-oriented design: Designed for current measurement and electrical energy metering in low-voltage distribution systems.
Two model series: LFZD-0.66 and LMZ□D-0.66 structures are available for different conductor layouts and primary current ranges.
Resin cast insulation: The unsaturated resin casting structure supports insulation performance, mechanical stability, and compact installation.
Fixed installation: The product adopts fixed mounting for metering cabinets, distribution panels, and energy metering boxes.
Multiple current ranges: Different structures cover primary current ranges from small-current metering circuits to higher-current busbar applications.
Standard secondary output: 5A or 1A secondary current can be selected according to the connected meter, instrument, or project requirement.

Working Principle

The LFZD-0.66 / LMZ□D-0.66 State Grid Metering Current Transformer current transformer operates according to electromagnetic induction. When the primary conductor or busbar carries current through the transformer window or primary structure, magnetic flux is generated in the core. The secondary winding outputs a proportional low-current signal, normally 5A or 1A, for connected energy meters or measuring instruments. This enables safe and standardized current measurement in low-voltage metering circuits.

Model Designation

The model codes can be interpreted as follows:

Code	Meaning
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: 0.66kV
D	Metering application / dedicated metering design code
30, 40, 60, 80, etc.	Typical window or structural size code according to selected model

Technical Data

Item	Specification
Rated voltage	0.66kV / 660V
Rated frequency	50Hz
Rated primary current	5A to 1500A according to model and catalogue data; other ratios can be confirmed by technical agreement
Rated secondary current	5A or 1A
Accuracy class	0.2, 0.2S, 0.5, 0.5S; subject to selected ratio and order requirements
Rated output	2.5VA, 5VA, 10VA, 15VA or 20VA according to model, ratio, and accuracy class
Ambient temperature	-5°C to +40°C
Installation method	Fixed installation
Insulating medium	Unsaturated resin casting
Applicable standards	GB/T 20840.2-2014, IEC 61869-2:2012, IEC 60044-1:2003; project-specific requirements can be confirmed by agreement

Rated Current, Accuracy and Output Reference

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

Note: Technical parameters beyond the above range can be confirmed through technical agreement between manufacturer and purchaser.

Service Conditions

Installation location: indoor
System voltage: 0.66kV and below
Rated frequency: 50Hz
Ambient temperature: -5°C to +40°C
The installation environment should be free from severe vibration, conductive dust, corrosive gas, explosive medium, and heavy pollution.
For special altitude, humidity, pollution level, metering box layout, or installation space requirements, technical confirmation is recommended before ordering.

Standards and Compliance

The LFZD-0.66 / LMZ□D-0.66 series current transformer is designed for low-voltage metering current transformer applications and can be supplied according to GB/T 20840.2-2014, IEC 61869-2:2012, IEC 60044-1:2003, and customer-specific technical requirements. For grid metering projects or special acceptance requirements, the final standards, test items, and nameplate data should be confirmed in the technical agreement.

Installation and Dimensions

The LFZD-0.66 / LMZ□D-0.66 series includes several outline structures for different rated primary current ranges. Round-hole and rectangular-window designs are available depending on the selected model and conductor arrangement. Final dimensions should be confirmed according to the approved drawing before production or batch ordering.

Model Structure and Current Range Reference

Model Structure	Typical Rated Primary Current Range	Structure Reference	Application Note
LFZD-0.66-30	5A–300A	Compact round-hole cast-resin type	Suitable for small-current metering circuits
LFZD-0.66-40	200A–600A	Round-hole cast-resin type	Suitable for medium-current metering circuits
LFZD-0.66-60	600A–800A	Large round-hole cast-resin type	Suitable for higher-current busbar or conductor applications
LMZ□D-0.66-50	400A–500A	Rectangular-window cast-resin type	Suitable for flat busbar metering installation
LMZ□D-0.66-80	800A–1500A	Large rectangular-window cast-resin type	Suitable for higher-current flat busbar metering installation

Unit: mm for dimensional drawings. Final dimensions are subject to confirmed drawing and selected specification.

Installation and Safety Notes

Confirm the CT model, current ratio, accuracy class, rated output, and outline structure before installation.
Check that the busbar, cable, or conductor size matches the selected CT window or through-hole dimension.
Install the product by fixed mounting according to the approved metering cabinet or distribution panel layout.
Connect secondary terminals according to polarity marks such as S1 and S2 and the project wiring diagram.
The secondary circuit of a current transformer must not be open-circuited when the primary circuit is energized.
Secondary wiring, grounding, sealing, and terminal protection should comply with metering project specifications and local electrical regulations.
Installation and maintenance should be performed by qualified electrical personnel.

Ordering Information

Please provide the following information when ordering or requesting a quotation:

Product model: LFZD-0.66 or LMZ□D-0.66
Detailed structure or size code, such as LFZD-0.66-30, LFZD-0.66-40, LFZD-0.66-60, LMZ□D-0.66-50, or LMZ□D-0.66-80
Rated primary current and rated secondary current
Accuracy class and rated output / burden in VA
System frequency and installation environment
Conductor type: busbar, cable, or round conductor
Quantity and metering cabinet application
Special requirements for terminal sealing, labels, drawings, inspection documents, certificates, or packaging

Selection Guidelines

Confirm the model series: Select LFZD-0.66 or LMZ□D-0.66 according to conductor form, installation layout, and metering cabinet design.
Confirm system voltage: The product is suitable for indoor low-voltage AC systems rated up to 0.66kV.
Confirm current ratio: Select the primary current according to the normal operating current and metering range of the circuit.
Select secondary current: Choose 5A or 1A according to the energy meter, measuring instrument, or secondary wiring requirement.
Select accuracy class: Use 0.2 or 0.2S for higher metering requirements, and 0.5 or 0.5S for general measurement applications.
Confirm rated burden: The total burden of meter, instrument, terminal wiring, and cable should not exceed the rated output of the CT.
Confirm installation dimensions: Check the outline drawing, terminal location, and cabinet clearance before batch installation.

FAQs

They are mainly used for current measurement and electrical energy metering in indoor low-voltage AC systems rated up to and including 0.66kV.

LFZD-0.66 is typically supplied in a cast-resin round-hole structure for metering applications, while LMZ□D-0.66 is commonly used for rectangular-window or busbar-type metering installation. The final model should be selected according to conductor layout and current range.

This series is suitable for low-voltage AC systems with rated voltage up to and including 0.66kV.

The rated secondary current can be selected as 5A or 1A according to the connected energy meter, measuring instrument, or project wiring requirement.

Common accuracy classes include 0.2, 0.2S, 0.5, and 0.5S. The final accuracy class should be selected according to the metering requirement, rated burden, and project specification.

The current ratio should be selected according to the normal operating current of the circuit and the metering range required by the energy meter. The selected ratio should allow reasonable load fluctuation while maintaining the required measurement accuracy.

The product adopts fixed installation. The specific mounting arrangement depends on the selected model, conductor form, and metering cabinet layout.

This series is mainly designed for indoor installation. Outdoor use requires a current transformer structure suitable for outdoor environmental conditions.

When the primary circuit is energized, the CT secondary circuit must not be open-circuited. An open secondary circuit may generate high voltage, damage insulation, affect product safety, and create risk for maintenance personnel.

Please provide the model, structure or size code, primary current, secondary current, accuracy class, rated output, system frequency, conductor type, quantity, and any special requirements for terminal sealing, labels, drawings, certificates, inspection documents, or packaging.

LFZ1D-0.66, LMZ□D-0.66 State Grid Metering Current Transformer