Product Overview
The LJZN1-10 metering current transformer is an indoor epoxy cast-resin current transformer designed for State Grid metering applications. It is used for current measurement, electric energy metering and billing-grade metering circuits in 10 kV, 11 kV and 12 kV class medium-voltage power systems.
The supplied data indicates compliance with Q/GDW 11681-2017 and special customer requirements. The standard accuracy combination is 0.2S / 0.2S, with rated secondary current of 5 A or 1 A. It is suitable for power metering cabinets, State Grid-style measurement panels and indoor medium-voltage switchgear requiring accurate current input for energy metering devices.
Product Type
| Item | Specification |
|---|---|
| Product name | Indoor Epoxy Cast-Resin Metering Current Transformer |
| Model series | LJZN1-10 |
| Application type | State Grid metering current transformer |
| Structure | Indoor, epoxy cast-resin, fully enclosed support-type structure |
| System voltage application | 10 kV, 11 kV and 12 kV class medium-voltage systems |
| Rated insulation level | 12/42/75 kV |
| Rated frequency | 50 Hz |
| Rated secondary current | 5 A or 1 A |
| Accuracy combination | 0.2S / 0.2S |
| Ambient temperature | -25°C to +55°C |
Product Display
Applications
- 10 kV, 11 kV and 12 kV class indoor medium-voltage metering cabinets
- State Grid-style power metering panels and utility metering units
- Energy billing systems requiring high metering accuracy
- Incoming and outgoing switchgear metering circuits
- Medium-voltage distribution rooms and industrial substation metering points
- Measurement circuits requiring 0.2S / 0.2S accuracy combination
Features
- Metering-focused design: The LJZN1-10 is mainly used for energy metering applications rather than general multi-core protection CT functions.
- 0.2S / 0.2S accuracy: The accuracy combination supports high-precision current measurement for billing and metering circuits.
- State Grid standard reference: The product is designed according to Q/GDW 11681-2017 and customer-specific technical requirements.
- Wide ambient range: The -25°C to +55°C operating temperature range supports demanding indoor metering environments.
- Epoxy cast-resin insulation: Fully enclosed dry-type insulation improves dielectric stability, moisture resistance and mechanical protection.
- Clear metering selection: The technical table is organized by rated primary current, rated output and thermal/dynamic current values for metering project selection.
Principle
The LJZN1-10 current transformer works by electromagnetic induction. The primary current generates magnetic flux in the magnetic core, and the secondary winding outputs a proportional low-current signal to the metering device. For energy metering use, the CT must keep ratio error and phase displacement within the required accuracy range under the specified rated burden.
Because this product is used for metering rather than heavy protection configuration, selection should focus on the rated primary current, rated secondary current, accuracy class, rated output and the matching burden of the meter and secondary wiring. The secondary circuit shall remain closed during operation, and a proper shorting device should be used for maintenance.
Model Designation
| Code | Meaning |
|---|---|
| L | Current transformer |
| J | Metering / measurement application series |
| Z | Epoxy resin casting insulation |
| N | Indoor type / special metering structure code |
| 1 | Design serial number |
| 10 | 10 kV catalogue voltage class; suitable for 10 kV, 11 kV and 12 kV class systems when insulation coordination is confirmed |
This model adopts an indoor fully enclosed epoxy cast-resin insulation structure. The primary conductor, secondary winding and magnetic core are encapsulated in the resin body to provide stable insulation, mechanical strength and reliable long-term performance in indoor switchgear. Compared with general protection-oriented CTs, this product is positioned mainly for metering use, where ratio accuracy, phase displacement and secondary output consistency are more important than multi-function protection combinations.
Technical Data
| Item | Specification |
|---|---|
| Model | LJZN1-10 |
| System voltage application | 10 kV, 11 kV and 12 kV class systems |
| Rated insulation level | 12/42/75 kV |
| Rated frequency | 50 Hz |
| Rated secondary current | 5 A or 1 A |
| Accuracy class combination | 0.2S / 0.2S |
| Rated output | 10/10 VA for low-current range; 15/15 VA for higher-current range according to supplied data |
| Ambient temperature | -25°C to +55°C |
| Applicable standard | Q/GDW 11681-2017 and customer-specific requirements |
| Application | Measurement of State Grid metering current transformer |
Selection Table
The following table is arranged according to the supplied technical data. It is intended for preliminary website selection only. Final ratings shall follow the approved drawing, nameplate and factory test report.
| Rated
Primary Current (A) |
Accuracy
Class Combination |
Rated
Output (VA) |
Short-Time
Thermal Current |
Rated
Dynamic Current (kA) |
|---|---|---|---|---|
| 5, 10, 15 | 0.2S / 0.2S | 10 / 10 | 4 kA / 1s | 10 |
| 20, 25 | 15 / 15 | 5 kA / 2s | 12.5 | |
| 30, 40 | 8 kA / 2s | 20 | ||
| 50, 60 | 10 kA / 2s | 25 | ||
| 75, 80 | 16 kA / 2s | 40 | ||
| 100, 150, 200, 250 | 20 kA / 2s | 50 | ||
| 300, 400, 500 | 25 kA / 4s | 63 | ||
| 600, 750 | 31.5 kA / 4s | 80 |
Note: If project requirements exceed the listed data, final parameters shall be confirmed by agreement between manufacturer and purchaser.
Terminals
Primary terminals are marked as P1 / P2. Secondary terminals are connected to the metering circuit according to the wiring diagram and nameplate. Since this model is used for metering, correct polarity and secure secondary wiring are essential for accurate energy measurement.
| Terminal | Function | Engineering Note |
|---|---|---|
| P1 / P2 | Primary current terminals | Primary current direction shall follow the switchgear wiring diagram. |
| S1 / S2 | Secondary metering output | Used for energy meter or measuring device input. |
| Shorting terminal | Secondary maintenance safety | Recommended before disconnecting any meter or instrument. |
| Grounding point | Safety grounding | Grounding shall follow switchgear and metering cabinet requirements. |
Service Conditions
- Installation location: indoor medium-voltage switchgear or metering cabinet
- System voltage: 10 kV, 11 kV and 12 kV class networks
- Rated frequency: 50 Hz
- Ambient temperature: -25°C to +55°C
- The installation environment should be free from severe vibration, conductive dust, corrosive gas, explosive medium, heavy pollution and abnormal condensation.
- Metering wiring should be short, secure and matched with the rated output burden to maintain accuracy.
Standards and Compliance
The LJZN1-10 metering current transformer is designed according to Q/GDW 11681-2017 and special customer requirements. The product is intended for State Grid metering applications and should be selected according to the required current ratio, accuracy class, rated output and approved metering cabinet drawing. Routine inspection normally includes ratio verification, polarity test, accuracy test, insulation withstand test and appearance inspection.
Installation and Dimensions
The product adopts an indoor support-type structure with top primary terminals and lower secondary terminal arrangement. The sample drawing shows a compact metering CT body with a fixed base and terminal area. Before installation, confirm the mounting-hole position, primary terminal spacing, secondary terminal block location and grounding point according to the approved drawing.
Dimensions
| Item | Dimension / Note |
|---|---|
| Structure type | Indoor epoxy cast-resin metering CT |
| Primary terminal layout | Top P1 / P2 terminal arrangement |
| Secondary terminal area | Lower terminal block according to drawing |
| Mounting base | Fixed base with mounting holes according to outline drawing |
| Drawing confirmation | Required before metering cabinet production or replacement |
Safety Notes
- Confirm model, current ratio, rated secondary current, rated output and accuracy class before installation.
- Check primary terminal direction, secondary terminal marking and grounding point before wiring.
- Use the approved drawing for metering cabinet installation.
- Confirm polarity before connecting the energy meter.
- The secondary circuit of a current transformer must not be open-circuited when the primary circuit is energized.
- Before disconnecting a meter or instrument, short-circuit the secondary circuit through a proper shorting device.
- Installation and maintenance shall be performed by qualified electrical personnel.
Ordering Info
- Product model: LJZN1-10
- System voltage: 10 kV, 11 kV or 12 kV
- Rated primary current and rated secondary current
- Accuracy class combination: 0.2S / 0.2S
- Rated output requirement: 10/10 VA or 15/15 VA according to ratio
- Rated insulation level and standard requirement
- Metering cabinet drawing, terminal layout and mounting dimension requirement
- Quantity, certificates, routine test reports, labeling and packaging requirements
Selection Guide
- Confirm metering purpose: Select LJZN1-10 when the CT is required mainly for medium-voltage energy metering.
- Confirm voltage class: Use it for 10 kV, 11 kV and 12 kV class systems when insulation coordination is confirmed.
- Select current ratio: Choose the rated primary current according to feeder load and metering range.
- Check rated output: Match the rated output with the energy meter burden and secondary wiring burden.
- Verify accuracy: Confirm 0.2S / 0.2S accuracy requirement for the metering circuit.
- Check withstand current: Confirm short-time thermal current and dynamic current according to the switchgear fault level.
- Approve drawing: Confirm outline dimensions, terminal diagram and nameplate data before production.