Overview
The LDZJ1-10 is an indoor, epoxy resin cast, single-turn-through current transformer designed for medium-voltage AC systems with a rated voltage class of 10kV. It is suitable for use in 10kV, 11kV, and 12kV indoor switchgear applications, provided insulation levels and project specifications are confirmed. The unit features a ring-core structure with the primary conductor passing directly through the body, while the secondary winding and core are fully encapsulated in cast-resin insulation.
Engineered for current measurement, energy metering, and relay protection in 50Hz power systems, the LDZJ1-10 meets standard requirements for indoor medium-voltage distribution equipment. It is commonly installed in fixed switchgear, distribution cabinets, and power panels where compact, reliable current transformation is required under controlled environmental conditions.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Rated voltage class | 10kV (also applicable to 11kV and 12kV systems) |
| Rated frequency | 50Hz |
| Primary current (standard values) | 50A to 3150A |
| Secondary current | 5A or 1A |
| Accuracy class (metering) | 0.2, 0.5, 1.0 |
| Accuracy class (protection) | 5P10, 5P20, etc. |
| Insulation material | Epoxy resin casting |
| Core type | Annealed ring core |
| Installation type | Wall-through mounting |
| Application environment | Indoor only |
| Primary conductor | Single-turn-through (busbar or cable) |
| Secondary terminals | Screw-type terminal block |
Model Designation
- L: Current transformer
- D: Single-turn-through type
- Z: Epoxy resin casting insulation
- J: Extended output / enhanced output design
- 1: Design sequence code
- 10: Rated voltage class: 10kV class
Construction
The LDZJ1-10 features a robust cast-resin insulated structure, with the secondary winding and annealed ring core fully embedded in epoxy resin for superior electrical insulation and mechanical strength. The primary conductor passes axially through the center of the toroidal core without direct electrical contact, ensuring galvanic isolation between the high-voltage primary circuit and the low-voltage secondary circuit. The base of the cast body incorporates a rating plate area, an earthing bolt, and pre-molded mounting holes, enabling secure wall-through installation in fixed indoor switchgear assemblies. This construction ensures long-term reliability in dry, non-condensing indoor environments typical of medium-voltage distribution rooms and industrial substations.
Technical Parameters
Service Conditions
- Installation location: indoor medium-voltage switchgear
- Altitude: not over 1000m under standard service conditions
- Ambient temperature: -5°C to +40°C
- Relative humidity: less than 85% at 20°C reference condition
- Vibration performance: The product has passed direct vibration testing with 0.4g three sine waves, equivalent to nine-degree earthquake reference.
- Installation environment: The installation environment should be free from severe vibration beyond specified conditions, corrosive gas, explosive medium, conductive dust, heavy pollution and abnormal condensation.
Technical Parameters
Performance conforms with IEC standard and GB1208-87 Current Transformer.
| Parameter | Rated primary current (A) |
|
|---|---|---|
| 400, 600 | 800, 1000, 1200, 1500 |
|
| Rated secondary current (A) |
5 | 5 |
| Frequency (Hz) | 50 | 50 |
| Rated output (VA) |
0.2: 30 | 0.2: 10 |
| 0.5: 30 | 0.5: 10 | |
| 10P15: 30 | 10P15: 15 | |
| 1s thermal current (r.m.s) (kA) |
75×I1n | 50×I1n |
| Dynamic current (peak) (kA) |
120×I1n | 90×I1n |
| Rated insulation level (kV) |
11.5/42/75 | 11.5/42/75 |
Installation & Wiring
Installation Diagram
The LDZJ1-10 current transformer is designed for wall-through installation in fixed switchgear. The base of the cast-resin body includes mounting holes, an earthing bolt, and a rating plate. Prior to cabinet production, confirm the wall-through opening position, primary conductor path, secondary terminal access, and required clearances using the approved outline drawing.
Selection & FAQs
Selection Guide
- Confirm the 10kV-class insulation requirement; use on 11kV or 12kV systems only after the exact insulation level and project standard are approved.
- Select the primary ratio from maximum load, normal metering range and protection study within the 50A–3150A reference range.
- Choose 1A or 5A and specify each independent core as class 0.2, 0.5 or 1.0 measurement, or the required 5P protection class.
- Calculate instrument/relay plus secondary-lead burden and obtain a model-specific VA rating and accuracy-limit factor before ordering.
- Verify busbar or cable dimensions, wall opening, mounting holes, earthing bolt, terminal access, clearances, altitude and −5°C to +40°C environment.
Frequently Asked Questions
Q1: Can this epoxy resin CT be installed outdoors?
No, this model is strictly designed for indoor medium-voltage switchgear. The environment must be free from corrosive gases and abnormal condensation. Contact our team for specific environmental assessments.
Q2: How is the 1-second thermal short-circuit current rated?
The rated 1s thermal current is 75×I1n for 400-600A primary currents, and 50×I1n for 800-1500A. Please provide your exact primary current and fault level for factory verification.
Q3: Which accuracy class is suitable for protection relays?
The 10P15 accuracy class is designed for protection applications. It provides a 30VA output for lower primary currents and 15VA for higher currents. Confirm your specific burden requirements with our engineering team.
Q4: Why does this transformer require a clean installation environment?
The epoxy resin cast design requires an environment free from severe vibration, corrosive gas, and conductive dust. Ensure your switchgear room meets these conditions to maintain insulation performance.
Q5: Are custom primary current ratings available above 1500A?
Standard ratings cover 400A to 1500A. Custom primary currents beyond this range are subject to factory confirmation and technical evaluation. Please submit your detailed specifications for a tailored quote.
Q6: When are type test certificates provided before shipment?
Routine test certificates are provided upon completion of standard factory inspections. Type test reports are subject to confirmation based on your specific order volume. Contact our sales team for exact delivery timelines.
Q7: What is the maximum altitude for standard service conditions?
The maximum installation altitude is 1000 meters under standard service conditions. For projects exceeding this elevation, derating factors apply and must be confirmed during the design phase.