LMZD2-10Q Epoxy Cast-Resin Cable / Busbar-Through Wall-Mounted CTs

Product Overview

The LMZD2-10Q current transformer is an indoor epoxy cast-resin, fully enclosed cable/busbar-through wall-mounted current transformer designed for medium-voltage power systems. It is used for current measurement, electric energy metering, and relay protection in AC systems with rated frequency of 50Hz and rated voltage class of 10kV. For international project documentation, this product can be described for 10kV, 11kV and 12kV class indoor switchgear applications, subject to final insulation coordination and project requirements.

The LMZD2-10Q adopts a fully enclosed indoor epoxy resin casting structure. The hollow through-window design allows the primary cable, copper bar, or busbar to pass through the central aperture, while the secondary winding provides a standardized output signal for meters, relays, and monitoring devices. The reinforced structure and large aperture make it suitable for high-current feeder circuits, metering panels, and protection circuits in indoor medium-voltage switchgear. The product is not a wound-primary type; the primary cable or busbar passes through the hollow aperture, and the CT is fixed by the mounting plate for through-wall cabinet installation.

Compared with small-current winding-type CTs, the LMZD2-10Q is mainly used for higher rated primary currents. The catalogue data shows rated primary currents from 1200A to 5000A, with metering and protection accuracy combinations such as 0.2/5P, 0.5/5P, and 5P/5P. This makes the product suitable for applications requiring both measurement accuracy and protection coordination.

Product Type

Product Display

The LMZD2-10Q has a compact ring-shaped cast-resin body mounted on a metal base plate. The central aperture is designed for busbar or primary conductor passage, while the secondary terminals are arranged on the body for connection to measuring instruments, meters, protection relays, or monitoring systems.

Applications

• 10kV, 11kV and 12kV class indoor medium-voltage switchgear
• High-current feeder cabinets and incoming/outgoing panels
• Current measurement and electric energy metering circuits
• Relay protection and feeder monitoring circuits
• Cable or busbar through-wall current sensing in indoor distribution equipment
• Industrial substations, power distribution rooms, and utility metering systems

Features

• Fully enclosed epoxy resin casting: The resin-insulated body provides stable insulation performance, mechanical strength, and indoor environmental resistance.
• Cable/busbar-through hollow structure: The primary cable, copper bar, or busbar passes through the CT aperture, making it suitable for high-current switchgear applications.
• High-current range: Rated primary current covers 1200A to 5000A, supporting large feeder, incoming, and distribution circuits.
• Metering and protection cores: Accuracy combinations such as 0.2/5P, 0.5/5P, and 5P/5P support both measurement and protection requirements.
• Reinforced 10Q design: The Q type indicates a reinforced structure for high-current indoor CT applications.
• Clear dimensional selection: Different aperture and outline dimensions are available according to the selected current range.

Principle

The LMZD2-10Q current transformer operates according to electromagnetic induction. The primary current flowing through the busbar or conductor inside the aperture produces magnetic flux in the core. The secondary winding then outputs a proportional current signal for connected meters, relays, or monitoring equipment. The epoxy resin insulation provides electrical isolation between the medium-voltage primary circuit and the low-voltage secondary circuit.

For metering circuits, the CT must maintain the required ratio and phase accuracy under rated burden. For protection circuits, the 5P class core must provide a reliable secondary signal under fault-current conditions, allowing protection relays to operate correctly within the intended protection range.

Model Designation

The model code LMZD2-10Q can be interpreted as follows:

Technical Data

Selection Table

The following table is organized for responsive website display. Long headers are wrapped into two lines, and common parameters are grouped where the catalogue uses shared values.

Note: If user requirements exceed the listed catalogue range, parameters may be determined by agreement between manufacturer and purchaser.

Dimension Table

Unit: mm. The dimensions shown above are for 5P/5P inner-hole selection. Final outline dimensions shall be confirmed by the approved drawing.

Service Conditions

• Installation location: indoor medium-voltage switchgear
• Rated voltage: 10kV, 11kV and 12kV class systems by project confirmation
• Rated frequency: 50Hz
• Ambient temperature: -5°C to +40°C
• The installation environment should be free from severe vibration, corrosive gas, explosive medium, conductive dust, heavy pollution, and abnormal condensation.
• For high altitude, coastal, humid, heavy-pollution, or special service conditions, technical confirmation is recommended before ordering.

Standards and Compliance

The LMZD2-10Q current transformer is manufactured according to GB1208-2006, IEC60044-1:2003, and customer-specific requirements. For export projects, the technical documentation can also be reviewed against updated IEC instrument transformer requirements when specified by the purchaser. Routine tests normally include ratio verification, polarity check, accuracy test, insulation test, and power-frequency withstand test according to the agreed standard.

Installation and Dimensions

The LMZD2-10Q is designed for indoor cable or busbar through-wall installation. The central aperture, base plate dimensions, mounting holes, and secondary terminal position must be checked before switchgear production. The catalogue provides different aperture and outline dimensions for the 1200-2500A, 3000-3150A, 4000A, and 5000A ranges.

Dimensions

Safety Notes

• Confirm the rated primary current, accuracy combination, rated output, aperture size, and installation dimensions before production.
• Check busbar clearance, phase spacing, creepage distance, mounting holes, and secondary terminal accessibility.
• Wire the secondary terminals according to the approved wiring diagram and terminal marking.
• The secondary circuit of a current transformer must not be open-circuited while the primary circuit is energized.
• Before removing meters or protection relays, short-circuit the CT secondary circuit using an approved shorting device.
• One point of the secondary circuit should be grounded according to the project electrical safety practice.
• Installation and commissioning shall be carried out by qualified medium-voltage electrical personnel.

Ordering Info

• Product model: LMZD2-10Q
• Rated primary current and secondary current
• Accuracy class combination: 0.2/5P, 0.5/5P, or 5P/5P
• Rated output for each secondary core
• Required protection class: 5P10, 5P15, or 5P20
• Busbar size, aperture requirement, and installation drawing
• Applicable standard, routine test report, and certificate requirements
• Quantity, label language, packing method, and project documentation requirements

Selection Guide

1. Confirm system voltage: Use this model for 10kV, 11kV and 12kV class indoor switchgear after insulation coordination is confirmed.
2. Select current ratio: Choose the rated primary current according to feeder rated current and busbar capacity.
3. Choose core combination: Use 0.2 or 0.5 for metering and 5P class for protection. For dual protection use, select 5P/5P.
4. Check rated output: Ensure the connected meter, relay, and cable burden do not exceed the rated secondary output.
5. Verify protection class: Select 5P10, 5P15, or 5P20 according to relay protection requirements.
6. Confirm dimensions: Match aperture size and base plate dimensions with the busbar and switchgear structure.
7. Review standards: Confirm GB1208-2006, IEC60044-1:2003, or project-specific standard requirements before ordering.

FAQs