Product Overview
The LQZJ-10 current transformer is an indoor, single-phase, epoxy resin cast, fully enclosed post-type current transformer designed for medium-voltage power systems. It is suitable for IEC-oriented 10kV, 11kV, and 12kV switchgear applications and is used for current measurement, electric energy metering, feeder monitoring, and relay protection in AC systems with rated frequency of 50Hz or 60Hz.
The product adopts a fully enclosed epoxy resin insulation structure. The coiled primary winding, secondary winding, and magnetic core are encapsulated inside the cast-resin body to provide insulation performance, moisture resistance, anti-pollution capability, mechanical strength, and compact installation. The lightweight post-type structure supports flexible installation direction in indoor switchgear, distribution cabinets, and medium-voltage metering or protection panels.
Product Type
| Item | Specification |
|---|---|
| Product name | Indoor Epoxy Resin Cast Fully Enclosed Current Transformer |
| Model series | LQZJ-10 |
| Product structure | Indoor single-phase, coiled type, epoxy resin cast, fully enclosed post-type current transformer |
| Voltage class | 10kV, 11kV, and 12kV medium-voltage systems |
| Highest voltage for equipment | 12kV class |
| Rated insulation level | 12/42/75kV |
| Rated frequency | 50Hz / 60Hz |
| Rated secondary current | 5A or 1A according to project requirement |
| Application type | Current measurement, electric energy metering, relay protection, and switchgear monitoring |
| Installation location | Indoor medium-voltage switchgear, metering panels, and distribution equipment |
| Applicable standard | IEC 61869-1 / IEC 61869-2; IEC 60044-1 can be referenced for legacy projects |
Product Display
Main Applications
- 10kV, 11kV, and 12kV indoor medium-voltage distribution systems
- Air-insulated switchgear, metering cabinets, feeder panels, and circuit breaker cabinets
- Current measurement and electric energy metering circuits
- Relay protection and feeder monitoring circuits
- Industrial substations, utility distribution rooms, and commercial power systems
- Indoor applications requiring compact coiled-type CT structure and stable insulation performance
Key Technical Features
- IEC voltage-class expression: Suitable for 10kV, 11kV, and 12kV systems with 12/42/75kV rated insulation level for 12kV-class insulation coordination.
- Coiled-type primary structure: The coiled primary design supports lower primary current applications and stable current transformation performance.
- Epoxy resin cast insulation: The winding system and magnetic core are encapsulated in resin to improve insulation strength, moisture resistance, and anti-pollution capability.
- Fully enclosed post-type body: The compact enclosed structure supports indoor cabinet mounting and easier surface cleaning.
- Measurement and protection use: The product can be configured for current measurement, energy metering, and relay protection circuits.
- Standard and customized ratios: Standard current ratios are available, and special ratios, burdens, secondary currents, and terminal arrangements can be confirmed by technical agreement.
Working Principle
The LQZJ-10 current transformer operates according to electromagnetic induction. Primary current flowing through the coiled primary winding generates magnetic flux in the magnetic core, and the secondary winding outputs a proportional current signal to 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 circuit.
For metering circuits, the CT should maintain the required ratio accuracy and phase displacement within the rated burden. For relay protection circuits, the protection winding should provide a reliable current signal under fault conditions and coordinate with the relay setting, rated burden, and short-circuit withstand requirement.
Model Designation
The model designation identifies the product type, coiled winding structure, insulation method, enhanced configuration, and voltage class.
| Code | Meaning |
|---|---|
| L | Current transformer |
| Q | Coiled type / coil-wound primary structure |
| Z | Cast-resin insulation |
| J | Enhanced type / reinforced design configuration |
| 10 | Voltage class identification; applicable to 10kV systems and IEC 12kV-class insulation coordination for 10kV, 11kV, and 12kV projects |
Technical Data
| Item | Specification |
|---|---|
| Rated voltage class | 10kV / 11kV / 12kV medium-voltage systems |
| Highest voltage for equipment | 12kV class |
| Rated insulation level | 12/42/75kV |
| Rated frequency | 50Hz / 60Hz |
| Rated primary current | 5A to 600A reference range; customized ratios available according to project requirement |
| Rated secondary current | 5A or 1A |
| Accuracy class combination | 0.2 / 0.5, 0.5 / 0.5, 0.2 / 10P, 0.5 / 10P or project-specific measuring / protection combinations |
| Rated output | 10VA / 15VA or project-specific burden according to secondary core configuration |
| Protection accuracy class | 10P or project-specific protection class |
| Partial discharge test | Available according to IEC 61869 project requirement |
| Insulation medium | Epoxy resin casting insulation |
| Installation method | Indoor post-type mounting according to approved drawing |
| Applicable standard | IEC 61869-1 / IEC 61869-2; IEC 60044-1 can be referenced for legacy specification |
Windings & Terminal Marking
The LQZJ-10 current transformer can be supplied with measuring, metering, protection, or combined secondary winding configurations. Terminal markings shall be confirmed according to the selected secondary core configuration and the approved wiring diagram.
| Terminal Marking | Function | Application Note |
|---|---|---|
| P1 / P2 | Primary terminals | The reference primary current direction is normally defined from P1 to P2. |
| 1S1 / 1S2 | First secondary winding | Usually used for measurement, metering, or the first specified secondary core. |
| 2S1 / 2S2 | Second secondary winding | Usually used for relay protection or an additional secondary circuit when required. |
| Secondary terminal cover | Secondary wiring protection | Terminal cover supports safer inspection and reduces accidental contact risk. |
Terminal markings follow standard CT polarity conventions. Correct terminal identification shall be observed to ensure metering accuracy, relay direction judgment, and protection performance. The secondary circuit must not be open-circuited when the primary circuit is energized.
DATA Reference
| Rated
Primary Current (A) |
Accuracy
Class Combination |
Rated
Secondary Current (A) |
Rated
Output (VA) |
Application
Note |
|---|---|---|---|---|
| 5–50 | 0.2 / 0.5 0.5 / 0.5 0.2 / 10P 0.5 / 10P |
5 or 1 | 10 / 15 | Low-current metering or protection circuits |
| 75–100 | 10 / 15 | Metering and feeder monitoring applications | ||
| 150–200 | 10 / 15 | Standard switchgear metering and protection circuits | ||
| 300–400 | 15 / 15 | Medium-current feeder applications | ||
| 500–600 | 15 / 20 | Higher current feeder or customized protection applications |
Note: The table is for preliminary engineering selection. Final current ratio, secondary current, accuracy class, rated output, thermal current, dynamic current, insulation level, partial discharge requirement, and terminal arrangement shall be confirmed according to nameplate data, approved drawings, and factory test reports.
Service Conditions
- Installation location: indoor medium-voltage switchgear
- System voltage: 10kV, 11kV, or 12kV class
- Rated frequency: 50Hz / 60Hz
- Rated insulation level: 12/42/75kV
- Altitude: not over 1000m under standard service conditions unless otherwise specified
- Ambient temperature: -5°C to +40°C
- The installation environment should be free from severe vibration, corrosive gas, explosive medium, heavy pollution, and abnormal condensation.
- For high altitude, high humidity, coastal, heavy-pollution, or special switchgear applications, technical confirmation is recommended before ordering.
Standards and Compliance
The LQZJ-10 current transformer can be supplied according to IEC 61869-1 and IEC 61869-2. IEC 60044-1 may be referenced for legacy project specifications. Routine tests, dielectric tests, polarity verification, ratio test, accuracy test, insulation resistance, and partial discharge requirements should be confirmed according to the final technical agreement.
Installation and Dimensions
The LQZJ-10 series is designed for indoor switchgear installation. The cast-resin body, primary terminal arrangement, secondary terminal cover, mounting structure, terminal direction, and electrical clearances shall be confirmed according to the approved outline drawing before cabinet design or batch production.
Structure & Overall Dimensions
| Item | Selection Note |
|---|---|
| Mechanical structure | Indoor epoxy resin cast, fully enclosed post-type current transformer |
| Primary structure | Coiled-type primary winding according to current ratio and design configuration |
| Primary terminals | P1 / P2 terminal arrangement according to approved drawing |
| Secondary terminals | 1S1 / 1S2 and optional 2S1 / 2S2 according to secondary core configuration |
| Drawing confirmation | Final outline, terminal direction, and mounting dimensions shall be confirmed before switchgear production |
Safety Notes
- Confirm the model, voltage class, current ratio, secondary current, accuracy class, burden, insulation level, and short-circuit withstand requirement before installation.
- Check switchgear mounting space, primary terminal connection, phase clearance, grounding arrangement, and maintenance access against the approved drawing.
- Connect primary and secondary terminals according to terminal markings and the project wiring diagram.
- The secondary circuit of a current transformer must not be left open when the primary circuit is energized.
- During meter or relay maintenance, short-circuit the CT secondary circuit before disconnecting any secondary wiring.
- Secondary grounding shall follow the project specification and local electrical safety requirements.
- Installation and maintenance shall be performed by qualified medium-voltage electrical personnel.
Ordering Information
Please provide the following information when ordering or requesting a quotation:
- Product model: LQZJ-10
- System voltage: 10kV, 11kV, or 12kV
- Rated primary current / current transformation ratio
- Rated secondary current: 1A or 5A
- Accuracy class combination and rated output for each secondary core
- Protection class and relay protection requirement if applicable
- Short-circuit withstand requirement if specified
- Insulation level and applicable IEC standard
- Switchgear type, installation layout, terminal direction, and required outline drawing
- Quantity, labeling, certificates, routine test reports, and packaging requirements
- Special customized current ratio, secondary winding, burden, or terminal arrangement requirements
Selection Guidelines
- Confirm voltage level: Select LQZJ-10 for indoor 10kV, 11kV, or 12kV switchgear using 12kV-class insulation coordination.
- Confirm primary current: Select the rated primary current according to feeder load, metering range, and protection setting range.
- Confirm secondary current: Use 5A or 1A according to connected meters, relays, cable length, and total burden calculation.
- Define accuracy combination: Specify measurement, metering, and protection accuracy classes according to the secondary circuit requirement.
- Check rated burden: Ensure the connected burden, including instruments and wiring, does not exceed the rated output of each secondary core.
- Confirm insulation and PD requirements: For IEC projects, confirm insulation level, partial discharge requirement, and test documentation before production.
- Confirm drawings: Verify outline dimensions, terminal direction, mounting arrangement, and electrical clearances before switchgear integration.