LZZBJ9-12/150b/2S Epoxy Resin Casting Type Current Transformer

Product Overview

The LZZBJ9-12/150b/2S current transformer, also referenced as AS12/150b/2S, is an indoor epoxy resin cast, dry-type, fully enclosed support-type current transformer for medium-voltage AC power systems. It is designed for current measurement, electric energy metering, feeder monitoring and relay protection in 10kV, 11kV and 12kV class indoor switchgear.

The product encapsulates the primary winding, secondary winding and magnetic core inside an epoxy resin casting body. This structure provides stable insulation performance, mechanical strength and reliable operation in indoor medium-voltage distribution equipment. The 150b structure is suitable for compact switchgear layouts where a reduced nominal width is required, while the 2S schematic configuration is used for two secondary circuits or two-core metering/protection arrangements.

For international IEC-style product pages, this product should be positioned as a 12kV indoor cast-resin current transformer for common 10kV, 11kV and 12kV networks. Final selection shall be confirmed according to current ratio, secondary current, accuracy class, rated output, short-circuit withstand requirement, terminal arrangement and approved outline drawing.

Product Type

Product Display

Applications

• 10kV, 11kV and 12kV class indoor medium-voltage switchgear
• Metal-clad switchgear, feeder panels, incoming cabinets and outgoing cabinets
• Current measurement and electric energy metering circuits
• Relay protection circuits for feeders, transformers, motors and distribution lines
• SCADA, power monitoring and distribution automation systems
• Compact switchgear layouts requiring a 150b nominal-width CT structure

Features

• 150b compact structure: The 150b nominal-width design is suitable for switchgear projects where installation space and terminal layout must be carefully controlled.
• 2S secondary schematic: The 2S configuration supports two secondary circuits for metering, measurement, protection or combined applications.
• Fully enclosed cast-resin insulation: Epoxy resin encapsulation improves insulation stability, mechanical protection and indoor moisture resistance.
• IEC-style 12kV class application: Suitable for common international 10kV, 11kV and 12kV medium-voltage systems with 12/42/75kV insulation level.
• 1A or 5A secondary output: Compatible with energy meters, measuring instruments, protection relays and monitoring devices.
• Metering and protection combinations: Measuring classes and protection classes can be configured according to project requirements and relay settings.

Principle

The LZZBJ9-12/150b/2S current transformer operates according to electromagnetic induction. The primary current flowing through the primary path generates magnetic flux in the magnetic core. The secondary winding produces a proportional current signal for connected meters, relays or monitoring devices. The epoxy resin casting body provides electrical insulation between the medium-voltage primary circuit and the low-voltage secondary circuits.

For metering applications, the secondary core shall maintain ratio accuracy and phase displacement within the rated burden. For protection applications, the protection core shall provide a reliable current signal during fault-current conditions and coordinate with relay settings. The short-time thermal current and dynamic current must match the switchgear fault level.

Model Designation

The model code can be interpreted as follows:

Technical Data

Terminals

The 2S schematic structure indicates a two-secondary arrangement. The product may be supplied with separate secondary circuits for metering and protection. Typical terminal markings include P1 / P2 for the primary side and 1S1 / 1S2, 2S1 / 2S2 for secondary cores. Final terminal arrangement shall be confirmed according to the approved drawing and nameplate.

Selection Table

The following table is arranged by current range and common metering/protection requirements. Long accuracy and output data are wrapped into multiple lines to improve readability on website pages and mobile layouts.

Note: The above values are for technical selection reference. If project requirements exceed the listed range, final parameters shall be confirmed by agreement between manufacturer and purchaser. Nameplate data, approved drawings and factory test reports shall prevail.

Structure Reference

Service Conditions

• Installation location: indoor medium-voltage switchgear
• System voltage: 10kV, 11kV and 12kV class networks
• Rated frequency: 50Hz / 60Hz
• Ambient temperature: -5°C to +40°C
• The installation environment should be free from severe vibration, conductive dust, corrosive gas, explosive medium, heavy pollution and abnormal condensation.
• For high altitude, humid, coastal, high-pollution or special switchgear conditions, technical confirmation is required before ordering.

Standards and Compliance

The LZZBJ9-12/150b/2S current transformer can be supplied according to GB 20840.1-2010, GB 20840.2-2014 and special project requirements. For international projects, IEC 61869-1 and IEC 61869-2 may be used as reference standards when required by the technical agreement. Routine tests typically include ratio test, polarity verification, accuracy test, dielectric withstand test, insulation inspection and appearance inspection.

Installation and Dimensions

The product adopts an indoor support-type structure with top primary terminals and lower secondary terminal arrangement. The 150b structure is more compact than larger-width variants and shall be selected according to switchgear mounting space, terminal direction, busbar clearance and secondary terminal access.

Dimensions

Safety Notes

• Confirm model, current ratio, secondary current, accuracy combination, rated output and insulation level before installation.
• Check mounting space, busbar connection, primary terminal position, secondary terminal layout and phase clearance before assembly.
• Use the approved drawing for the selected 150b/2S structure and terminal arrangement.
• Connect P1/P2 and secondary terminals according to polarity markings and the project wiring diagram.
• The secondary circuit of a current transformer must not be open-circuited when the primary circuit is energized.
• Before disconnecting meters or relays, short-circuit the secondary circuit through an approved shorting terminal block.
• Installation and maintenance shall be performed by qualified medium-voltage electrical personnel.

Ordering Info

• Product model: LZZBJ9-12/150b/2S, AS12/150b/2S or AS12150b/2S
• Rated primary current and rated secondary current
• Accuracy class combination and rated output for each secondary core
• Rated insulation level and applicable standard
• Required short-time thermal current and dynamic current
• Secondary core quantity, schematic code and terminal marking requirement
• Switchgear layout, mounting dimensions and primary terminal direction
• Quantity, certificates, routine test reports, labeling and packaging requirements

Selection Guide

1. Confirm voltage class: Select this CT for 10kV, 11kV and 12kV class indoor switchgear.
2. Confirm structure: Use LZZBJ9-12/150b/2S when the switchgear requires the 150b nominal-width structure and 2S secondary schematic layout.
3. Select current ratio: Choose the rated primary current according to feeder load, metering range and protection setting.
4. Define secondary cores: Specify each secondary core separately, including accuracy class, protection level and rated output.
5. Check rated burden: Confirm that meter, relay and cable burden do not exceed the rated output of each secondary core.
6. Verify fault rating: Rated short-time thermal current and rated dynamic current shall match the switchgear fault level.
7. Confirm dimensions: Check primary terminal layout, busbar spacing, secondary terminals and cabinet clearance before production.

FAQs