Product Overview
The LZZJ-10 / LZZJ-12(Q) / LZZ(B)J1-10 current transformer is an indoor epoxy cast-resin, fully enclosed, post-type current transformer for medium-voltage AC power systems. It is designed for current measurement, energy metering, feeder monitoring and relay protection in 10kV, 11kV and 12kV class indoor switchgear.
This product family uses a cast-resin insulated body with compact post-type construction. The magnetic core and secondary winding are encapsulated inside the epoxy resin body, while the primary terminals are arranged on the top side for busbar connection. It is suitable for indoor fixed switchgear, feeder cabinets, metering panels and protection circuits where stable insulation, compact size and reliable secondary signal output are required.
For international product pages, the series can be presented under the 12kV insulation class because the typical insulation level is 12/42/75kV. LZZJ-10, LZZJ-12(Q) and LZZ(B)J1-10 should be selected according to project voltage class, mounting dimensions, current ratio, secondary output, accuracy combination and approved drawing.
Product Type
| Item | Specification |
|---|---|
| Product name | Indoor Epoxy Cast-Resin Current Transformer |
| Model series | LZZJ-10 / LZZJ-12(Q) / LZZ(B)J1-10 |
| Structure | Indoor, fully enclosed, post-type, epoxy cast-resin insulated structure |
| Voltage class | 10kV, 11kV and 12kV class medium-voltage systems |
| Rated insulation | 12/42/75kV |
| Rated frequency | 50Hz |
| Secondary current | 5A or 1A |
| Phase | Single phase |
| Installation | Indoor busbar / post-type switchgear installation |
| Applications | Protection, measurement, energy metering and feeder monitoring |
Product Display
Applications
- 10kV, 11kV and 12kV class indoor medium-voltage distribution systems
- Fixed switchgear, feeder cabinets, incoming panels and outgoing panels
- Current measurement and electric energy metering circuits
- Relay protection circuits for feeders, transformers, motors and distribution lines
- SCADA, power monitoring and distribution automation systems
- Indoor projects requiring compact post-type epoxy cast-resin current transformers
Features
- Fully enclosed cast-resin structure: The epoxy resin body provides insulation strength, mechanical protection and stable indoor operating performance.
- Post-type support design: The structure is suitable for indoor busbar connection and fixed switchgear installation, with primary terminals arranged for reliable bolted connection.
- 10kV to 12kV class coverage: With 12/42/75kV insulation level, the series can be used in common international 10kV, 11kV and 12kV systems.
- Measurement and protection cores: Accuracy classes such as 0.2S, 0.5, 1 and 10P10 can be selected according to metering or relay protection requirements.
- 5A or 1A secondary output: Secondary current can be selected according to meter input, relay input, wiring distance and secondary burden.
- Single and double ratio options: Single-ratio and double-ratio configurations can be supplied when required by switchgear and protection design.
Principle
The LZZJ-10 / LZZJ-12(Q) / LZZ(B)J1-10 current transformer operates according to electromagnetic induction. Primary current flowing through the primary conductor produces magnetic flux in the core, and the secondary winding outputs a proportional current signal to the connected meter, relay or monitoring device. The epoxy resin body provides electrical insulation between the medium-voltage primary circuit and the low-voltage secondary circuit.
For metering applications, the selected secondary core must maintain ratio accuracy and phase displacement within the rated burden. For protection applications, the 10P core must provide a reliable current signal under fault conditions so that the relay can operate correctly within the required protection range.
Model Designation
The model code can be interpreted as follows:
| Code | Meaning |
|---|---|
| L | Current transformer |
| Z | Indoor type |
| Z | Epoxy resin cast insulation / fully enclosed structure |
| B | Protection class available, used where metering and protection cores are required |
| J | Reinforced / enhanced design |
| 1 / 2 | Design sequence or structure series code |
| 10 / 12 | 10kV catalogue code / 12kV international insulation class |
| Q | Enhanced insulation type in some catalogue designations |
Technical Data
| Item | Specification |
|---|---|
| Rated voltage class | 10kV, 11kV and 12kV class indoor systems |
| Rated insulation | 12/42/75kV |
| Rated frequency | 50Hz |
| Rated primary current | 5A to 1500A reference range; 5A to 1000A common catalogue range |
| Rated secondary current | 5A or 1A |
| Accuracy class | 0.2S, 0.5, 1, 10P10 and combined metering/protection classes |
| Rated output | 10VA, 15VA, 20VA or 25VA according to current ratio and core configuration |
| Winding form | Single-layer and tightly wound type; single-ratio or double-ratio configuration |
| Insulating medium | Epoxy resin |
| Magnetic circuit | Combined type |
| Ambient temperature | -5°C to +55°C reference |
| Applicable standards | GB1208-2006, IEC 60044-1:2003 and project-specific requirements |
Terminals
The current transformer can be supplied with one or multiple secondary windings according to the metering and protection scheme. Typical terminals include P1 / P2 for the primary side and 1S1 / 1S2, 2S1 / 2S2 or additional tap terminals for secondary circuits.
| Terminal Marking |
Function | Application Note |
|---|---|---|
| P1 / P2 | Primary terminals | Primary current direction and busbar connection shall follow the drawing and wiring diagram. |
| 1S1 / 1S2 | First secondary winding | Usually used for metering, measurement or the first specified secondary core. |
| 2S1 / 2S2 | Second secondary winding | Used for relay protection or an additional measuring circuit according to core configuration. |
| Tap terminal | Double-ratio selection | Used when a tapped secondary or double-ratio configuration is specified. |
Single Ratio
The following table is a compact selection reference for single-ratio configurations. Long headers and shared values are wrapped to keep the table readable in responsive website layouts.
| Rated
Primary Current (A) |
Accuracy
Class Combination |
Rated
Output (VA) |
Short-Time
Thermal Current(kA/1s) |
Rated
Dynamic Current (kA) |
Remark |
|---|---|---|---|---|---|
| 5 | 0.2S / 10P10 0.2 / 10P10 0.5 / 10P10 10P10 / 10P10 0.5 / 0.5 0.5 / 0.5 / 10P10 0.2 / 0.5 / 10P10 |
0.5: 10 10P10: 15 |
0.5 / 2 | 1.25 | Single ratio |
| 10 | 1 / 2 | 2.5 | |||
| 15 | 1.5 / 2 | 3.75 | |||
| 20 | 2 / 2 | 5 | |||
| 30 | 3 / 2 | 7.5 | |||
| 40 | 4 / 2 | 10 | |||
| 50 | 5 / 2 | 12.5 | |||
| 75 | 8 / 2 | 20 | |||
| 100 | 10 / 2 | 25 | |||
| 150 | 0.5: 10 10P10: 15 |
16 / 2 | 40 | ||
| 200 | 20 / 2 | 50 | |||
| 300 | 20 / 4 | 50 | |||
| 400 | 20 / 4 | 50 | |||
| 500–600 | 0.5: 15 10P10: 15 |
25 / 4 | 63 | ||
| 800 | 0.5: 15 10P10: 20 |
32 / 4 | 80 | ||
| 1000 | 0.5: 20 10P10: 25 |
32 / 4 | 80 |
Double Ratio
The following table is a selection reference for double-ratio configurations. Final tap arrangement, terminal marking and ratio combination shall be confirmed by nameplate and approved drawing.
| Rated
Primary Current (A) |
Accuracy
Class Combination |
Rated
Output |
Short-Time
Thermal Current(kA/1s) |
Rated
Dynamic Current (kA) |
Remark |
|---|---|---|---|---|---|
| 20–30 | 0.2 / 10P10 0.5 / 10P10 10P10 / 10P10 |
0.5: 10 10P10: 15 |
1.2 / 2 | 4 | Double ratio |
| 30–40 | 3.15 / 2 | 8 | |||
| 40–50 | |||||
| 50–75 | 6.3 / 2 | 16 | |||
| 75–100 | |||||
| 100–150 | 8 / 2 | 20 | |||
| 150–200 | 12.5 / 4 | 31.5 | |||
| 200–300 | 20 / 4 | 50 | |||
| 300–400 | |||||
| 400–600 | 0.5: 15 10P10: 20 |
25 / 4 | 63 | ||
| 600–800 | 0.5: 15 10P10: 20 |
31.5 / 4 | 80 | ||
| 800–1000 | 0.5: 20 10P10: 25 |
Note: The above data is for selection reference. If user requirements go beyond the listed range, final parameters shall be confirmed by agreement between manufacturer and purchaser. Nameplate data, approved drawing and factory test report shall prevail.
Service Conditions
- Installation location: indoor medium-voltage switchgear
- System voltage: 10kV, 11kV and 12kV class networks
- Rated frequency: 50Hz
- Ambient temperature: -5°C to +55°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 or special switchgear applications, technical confirmation is required before ordering.
Standards and Compliance
The LZZJ-10 / LZZJ-12(Q) / LZZ(B)J1-10 current transformer is designed according to GB1208-2006, IEC 60044-1:2003 and special project requirements. For international projects, IEC 61869-1 and IEC 61869-2 can also be used as reference standards when required by the technical agreement. Routine tests typically include ratio test, polarity verification, accuracy test, insulation withstand test and appearance inspection.
The relation curve between accuracy limit factor and secondary load
Installation and Dimensions
The product adopts a compact post-type structure for indoor switchgear installation. The catalogue reference shows a compact resin body, top primary terminals and bottom secondary terminal arrangement. Final installation dimensions shall be confirmed by approved drawing before cabinet production.
Dimensions
| Item | Dimension / Note |
|---|---|
| Overall width | 286 ± 2mm reference |
| Base mounting length | 170mm reference |
| Side width | 176 ± 2mm reference |
| Overall height | 225 ± 2mm reference |
| Primary terminal spacing | 60mm / 30mm reference arrangement |
| Mounting hole reference | Confirmed according to approved outline drawing |
| Drawing confirmation | Required before switchgear production or replacement |
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.
- Connect P1/P2 and secondary terminals according to polarity markings and 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.
- One point of the secondary circuit should be grounded according to project requirements and local electrical safety regulations.
- Installation and maintenance shall be performed by qualified medium-voltage electrical personnel.
Ordering Info
Please provide the following information when ordering or requesting a quotation:
- Product model: LZZJ-10, LZZJ-12(Q) or LZZ(B)J1-10
- Single-ratio or double-ratio configuration
- Rated primary current and rated secondary current
- Accuracy class combination and rated output
- Rated insulation level and applicable standard
- Required short-time thermal current and dynamic current
- Terminal marking, tap arrangement and wiring diagram requirement
- Switchgear layout, mounting dimensions and primary terminal direction
- Quantity, certificates, routine test reports, labeling and packaging requirements
Selection Guide
- Confirm voltage class: Use this CT for indoor 10kV, 11kV and 12kV class systems with 12/42/75kV insulation level.
- Confirm model designation: Select LZZJ-10, LZZJ-12(Q) or LZZ(B)J1-10 according to project documents and approved drawings.
- Confirm ratio type: Select single ratio for fixed operating ranges or double ratio where two primary current ranges are required.
- Select primary current: Choose the rated primary current according to feeder load, metering range and protection settings.
- Define core functions: Specify metering and protection cores separately, including accuracy class and rated output.
- Check secondary burden: Confirm that meter, relay and cable burden do not exceed the rated output of each secondary core.
- Verify fault rating: Rated short-time thermal current and rated dynamic current shall match the switchgear fault level.
- Confirm dimensions: Check mounting holes, primary terminal layout, secondary terminals and cabinet clearance before production.