Overview
The LJZN2-10 is an indoor epoxy cast-resin metering current transformer designed for 10 kV, 11 kV, and 12 kV class medium-voltage systems. It features a fully enclosed structure with epoxy resin insulation, ensuring reliable performance in indoor metering environments.
This transformer delivers stable 0.2S-class current output for precision energy metering and billing applications. It is commonly used in State Grid-compliant metering cabinets, incoming panels, and utility measurement points. The design adheres to Q/GDW 11681-2017 standards and supports primary current ratios from 800 A to 2500 A with a rated output of 15/15 VA.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| System voltage class | 10 kV / 11 kV / 12 kV |
| 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 |
| Rated output | 15/15 VA |
| Primary current range | 800 A – 2500 A |
| Ambient temperature | -25°C to +55°C |
Model Designation
- 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
Construction
The LJZN2-10 features an indoor, fully enclosed construction using epoxy cast-resin insulation. This material provides excellent dielectric strength, mechanical stability, and resistance to environmental factors such as moisture and dust. The core and windings are completely encapsulated in solid epoxy resin, ensuring long-term reliability and minimal maintenance in indoor switchgear and metering cabinets. The design includes robust primary terminals configured for busbar connections, with layout variations optimized for different current ranges (800 A–1200 A and 1200 A–2500 A) to support practical cabinet integration.
Technical Parameters
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
- Installation environment: should be free from severe vibration, conductive dust, corrosive gas, explosive medium, heavy pollution and abnormal condensation.
- High-current metering considerations: verify busbar connection, terminal contact area, cabinet ventilation and secondary wiring burden.
Technical Parameters
The LJZN2-10 is an epoxy cast-resin current transformer designed for 10 kV class systems, compliant with Q/GDW 11681-2017. It operates within an ambient temperature range of -25°C to +55°C and supports primary currents from 800 A to 2500 A with dual 0.2S accuracy classes. The unit features a rated insulation level of 12/42/75 kV and is suitable for indoor metering applications in medium-voltage switchgear.
| Rated primary current (A) |
Accuracy classed combination |
Rated Output (VA) |
Short-time thermal current |
Rated dynamic current (kA) |
|
|---|---|---|---|---|---|
| 0.2S | 0.2S | ||||
| 800 | 0.2S/0.2S | 15 | 15 | 31.5kA/4s | 80 |
| 1000 | 40kA/4s | 100 | |||
| 1250 | |||||
| 1500 | |||||
| 2000 | |||||
| 2500 | |||||
Installation & Wiring
Installation Guidance
The LJZN2-10 epoxy cast-resin current transformer features an indoor support-type structure with primary terminals (P1/P2) located at the top and secondary terminals arranged at the lower section. Due to its high-current rating (800 A to 2500 A), careful attention must be paid to the primary busbar connection during installation.
Two distinct busbar layouts are used depending on the rated primary current:
- 800 A–1200 A range
- 1200 A–2500 A range
The correct layout must be selected according to the ordered current ratio. The mounting base includes fixed holes aligned with the outline drawing, which must be confirmed and approved before metering cabinet production or retrofitting.
Ensure that the secondary terminal block matches the wiring diagram provided in the approved documentation. All grounding provisions must be securely connected in accordance with local electrical codes.
Safety Notice
- 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.
Selection & FAQs
Selection Guide
- Confirm the utility metering specification, Q/GDW 11681-2017 requirement where applicable, and 12/42/75kV insulation coordination.
- Select 800A, 1000A, 1250A, 1500A, 2000A or 2500A from operating current and required billing accuracy across the normal load range.
- Choose 1A or 5A secondary and define the purpose, terminal assignment and one-point grounding of both 0.2S cores.
- Verify that the fixed 15VA per core covers the energy meter, test block and lead burden without exceeding the rated load.
- Approve the correct 800–1000A or 1250–2500A busbar layout, contact area, thermal/dynamic duty, ventilation, polarity and mounting drawing.
Frequently Asked Questions
Q1: What primary current range does this metering CT support?
It supports primary currents from 800 A to 2500 A. The unit features dual 0.2S accuracy classes for precise indoor metering. Contact us to verify specific ratio requirements.
Q2: Can this epoxy cast-resin transformer be installed outdoors?
No, it is strictly designed for indoor medium-voltage switchgear. The installation environment must be free from severe vibration, conductive dust, and corrosive gases.
Q3: Which short-time thermal current rating applies to this model?
The exact short-time thermal and dynamic current ratings depend on the selected primary current rating. Please provide your specific system fault levels for factory confirmation.
Q4: What factory tests are performed before shipping this equipment?
Routine tests are conducted to ensure compliance with Q/GDW 11681-2017 standards. Specific type test reports and calibration certificates are subject to confirmation during ordering.
Q5: How long is the standard delivery time for custom ratios?
Standard lead times apply to catalog models, but custom primary ratios require specific scheduling. Contact our sales team for exact delivery timelines based on your order quantity.
Q6: Where is the LJZN2-10 current transformer typically applied?
It is primarily applied in 10 kV, 11 kV, and 12 kV indoor metering cabinets. The epoxy cast-resin design ensures reliable performance in medium-voltage switchgear.
Q7: Why are special busbar connections needed for high-current metering?
High-current applications require verified busbar connections and adequate terminal contact areas to prevent overheating. Ensure cabinet ventilation and secondary wiring burden meet design specifications.