Product Overview
The LJZN2-10 metering current transformer is an indoor epoxy cast-resin current transformer developed for State Grid metering applications in 10 kV, 11 kV and 12 kV class medium-voltage systems. It is mainly used in metering cabinets, incoming metering panels and utility measurement points where stable 0.2S-class current signal output is required for energy measurement and billing-related circuits.
Compared with the LJZN1-10 model, the LJZN2-10 page should be positioned around higher primary-current metering applications. The supplied technical data focuses on 800 A to 2500 A ratios, with 15/15 VA rated output and 0.2S / 0.2S accuracy combination. Its larger terminal layout and busbar connection arrangement make it suitable for medium-voltage metering schemes with higher load current, while maintaining the same State Grid metering standard direction under Q/GDW 11681-2017.
Product Type
| Item | Specification |
|---|---|
| Product name | Indoor Epoxy Cast-Resin Metering Current Transformer |
| Model series | LJZN2-10 |
| Application type | State Grid metering current transformer for high-current metering panels |
| Structure | Indoor, epoxy cast-resin, fully enclosed metering CT 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 medium-voltage metering cabinets
- State Grid-style energy metering panels with higher primary current ratios
- Incoming metering units for distribution rooms and industrial substations
- Utility billing measurement circuits requiring 0.2S / 0.2S accuracy
- Metering points using 800 A, 1000 A, 1250 A, 1500 A, 2000 A or 2500 A ratios
- Indoor switchgear where metering accuracy and busbar terminal layout must both be confirmed
Features
- High-current metering range: The supplied data focuses on 800 A to 2500 A ratios, making this model different from low-current metering CT pages.
- 0.2S / 0.2S metering accuracy: Designed for precision current measurement in energy metering and billing-related circuits.
- 15/15 VA output: The rated output is suitable for metering circuits where instrument burden and secondary cable burden must be considered.
- State Grid standard reference: The product follows Q/GDW 11681-2017 and customer-specific requirements for metering CT projects.
- Two busbar layout ranges: The outline drawing separates the 800 A–1200 A layout and the 1200 A–2500 A layout, supporting more practical cabinet design.
- Wide service temperature: The -25°C to +55°C temperature range supports indoor metering cabinets under demanding operating conditions.
Principle
The LJZN2-10 current transformer converts medium-voltage primary current into a standardized secondary current signal through electromagnetic induction. The secondary signal is supplied to energy meters or metering instruments. For metering CTs, the critical design focus is not only current transformation, but also maintaining ratio accuracy and phase displacement within the specified 0.2S accuracy range under the rated burden.
Because this model is used for higher-current metering points, engineering selection should review the current ratio, 15/15 VA rated output, meter burden, secondary cable burden, primary busbar layout and thermal-current withstand requirement together. The approved drawing must be confirmed before metering cabinet fabrication, especially when switching between the 800 A–1200 A layout and the 1200 A–2500 A layout.
Model Designation
| Code | Meaning |
|---|---|
| L | Current transformer |
| J | Metering / measurement application series |
| Z | Epoxy resin casting insulation |
| N | Indoor type / State Grid metering structure code |
| 2 | Design serial number; higher-current metering variant compared with LJZN1-10 |
| 10 | 10 kV catalogue voltage class; suitable for 10 kV, 11 kV and 12 kV class systems when insulation coordination is confirmed |
Technical Data
| Item | Specification |
|---|---|
| Model | LJZN2-10 |
| 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 |
| Rated primary current range | 800 A, 1000 A, 1250 A, 1500 A, 2000 A and 2500 A reference ratios |
| Accuracy class combination | 0.2S / 0.2S |
| Rated output | 15/15 VA |
| Ambient temperature | -25°C to +55°C |
| Applicable standard | Q/GDW 11681-2017 and customer-specific requirements |
Selection Table
The following table is arranged according to the supplied LJZN2-10 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) |
|---|---|---|---|---|
| 800 | 0.2S / 0.2S | 15 / 15 | 31.5 kA / 4s | 80 |
| 1000 | 40 kA / 4s | 100 | ||
| 1250 | ||||
| 1500 | ||||
| 2000 | ||||
| 2500 |
Note: If project requirements exceed the listed data, final parameters shall be confirmed by agreement between manufacturer and purchaser.
Terminal Layout
The LJZN2-10 uses top primary terminals marked as P1 / P2 and a lower secondary terminal area for metering output. The supplied outline drawing shows two primary connection layouts: one for 800 A ≤ I1n < 1200 A and another for 1200 A ≤ I1n ≤ 2500 A. The correct terminal layout shall be selected before copper busbar processing.
| Current Range | Primary Layout Reference |
Engineering Note |
|---|---|---|
| 800 A ≤ I1n < 1200 A | Medium-current terminal layout | Used for 800 A and 1000 A metering cabinet applications. |
| 1200 A ≤ I1n ≤ 2500 A | High-current terminal layout | Used for 1250 A, 1500 A, 2000 A and 2500 A metering circuits. |
| Secondary terminal block | S1 / S2 or project-specific marking | Connect to the energy meter according to polarity and approved wiring diagram. |
| Grounding point | Cabinet grounding connection | Grounding shall follow metering cabinet and switchgear safety 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.
- For high-current metering applications, verify busbar connection, terminal contact area, cabinet ventilation and secondary wiring burden.
Standards and Compliance
The LJZN2-10 metering current transformer is designed according to Q/GDW 11681-2017 and customer-specific technical requirements. It is intended for State Grid-style energy metering applications where 0.2S-class measurement performance is required. 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 P1/P2 primary terminals and a lower secondary terminal arrangement. Compared with the LJZN1-10 low-current metering page, this model requires more attention to the primary busbar connection because the current range starts at 800 A and extends to 2500 A. The outline drawing must be confirmed before metering cabinet production.
Dimensions
| Item | Dimension / Note |
|---|---|
| Structure type | Indoor epoxy cast-resin high-current metering CT |
| Primary terminal layout | Top P1 / P2 terminal arrangement |
| Secondary terminal area | Lower terminal block according to drawing |
| Busbar layout | Separate layouts for 800 A–1200 A and 1200 A–2500 A ranges |
| 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.
- Use the correct busbar layout for the selected current range.
- Check primary terminal direction, secondary terminal marking and grounding point before wiring.
- 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: LJZN2-10
- System voltage: 10 kV, 11 kV or 12 kV
- Rated primary current: 800 A, 1000 A, 1250 A, 1500 A, 2000 A or 2500 A
- Rated secondary current: 5 A or 1 A
- Accuracy class combination: 0.2S / 0.2S
- Rated output requirement: 15/15 VA
- Metering cabinet drawing, busbar layout and terminal dimension requirement
- Quantity, certificates, routine test reports, labeling and packaging requirements
Selection Guide
- Confirm high-current metering need: Select LJZN2-10 when the metering point requires 800 A to 2500 A primary current ratios.
- Confirm voltage class: Use it for 10 kV, 11 kV and 12 kV class systems when insulation coordination is confirmed.
- Select busbar layout: Choose the correct primary terminal layout for 800 A–1200 A or 1200 A–2500 A ranges.
- Check rated output: Confirm that 15/15 VA matches the energy meter and secondary cable burden.
- Verify accuracy: Confirm 0.2S / 0.2S accuracy requirement for the metering circuit.
- Check withstand current: Confirm 31.5 kA/4s or 40 kA/4s thermal-current requirement according to the selected ratio.
- Approve drawing: Confirm outline dimensions, busbar hole position, terminal diagram and nameplate data before production.