Overview
The LDJ-10Q / LDJ-10/210-L(Y) is an indoor, epoxy resin cast, fully enclosed through-type current transformer designed for 10kV, 11kV, and 12kV medium-voltage systems. It features a 12/42/75kV rated insulation level and is built with a robust epoxy resin casting that ensures high dielectric strength, moisture resistance, and mechanical stability.
This current transformer supports both measurement and protection applications, with accuracy classes suitable for energy metering and 10P10 relay protection. It is specifically engineered for integration into KYN handcart-type switchgear and other compact indoor medium-voltage cabinets, providing reliable performance in AC power systems operating at 50Hz or 60Hz.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 10kV, 11kV, 12kV |
| Highest voltage for equipment | 12kV |
| Insulation level | 12/42/75kV |
| Rated frequency | 50Hz / 60Hz |
| Rated secondary current | 5A or 1A (2A on request) |
| Power factor of burden | cosφ = 0.8 lagging |
| Accuracy for metering | As per specified class (e.g., 0.2, 0.5) |
| Protection accuracy | 10P10 |
| Application type | Indoor, KYN handcart switchgear |
| Construction | Epoxy resin cast, fully enclosed |
| Primary terminal | One with terminal/contact box structure |
| Typical use | Measurement, metering, protection, monitoring |
Model Designation
- L: Current transformer
- D: Through-type / special switchgear current transformer structure
- J: Indoor epoxy resin cast insulation structure
- 10: Voltage class identification; used for 10kV systems and 12kV-class insulation coordination
- Q: Reinforced insulation or special structure variant when specified
- 210: Structural dimension / window or installation design code
- L: Special layout version for handcart switchgear application
Construction
The LDJ-10Q / LDJ-10/210-L(Y) current transformer features a fully enclosed construction with epoxy resin casting, providing excellent electrical insulation, mechanical strength, and environmental resistance. The core and windings are completely encapsulated in cast-resin material, ensuring long-term reliability in indoor switchgear environments. One primary lead-out terminal incorporates a terminal/contact box structure, facilitating secure and compact connection within KYN handcart switchgear. This design supports seamless integration into medium-voltage cabinets while maintaining compliance with standard insulation coordination for 12kV-class systems.
Technical Parameters
Service Conditions
- Installation location: indoor medium-voltage switchgear
- System voltage: 10kV, 11kV, or 12kV class
- Rated frequency: 50Hz / 60Hz
- Rated insulation level: 12/42/75kV
- Altitude: not exceeding 1000m under standard service conditions unless otherwise specified
- Ambient temperature: -5°C to +40°C standard reference range
Technical Parameters
The LDJ-10Q and LDJ-10/210-L(Y) current transformers are designed for indoor use in 10kV–12kV medium-voltage KYN handcart switchgear. They feature epoxy resin casting insulation, operate within a standard ambient temperature range of -5°C to +40°C, and are rated for altitudes up to 1000m. Compliant with IEC 61869-1/-2, they support primary currents from 5A to 3150A and secondary currents of 1A or 5A (2A by special request).
| Rated Primary Current (A) |
Accuracy Classes Combination |
Rated Output (VA) |
Rated Short-Time Thermal Current (kA/1S) |
Rated Dynamic Current (kA) |
|---|---|---|---|---|
| 5 | 0.2/5P10 0.2S/5P10 0.5/5P10 0.2/10P10 0.2S/10P10 0.5/10P10 |
10/15 | 0.3 | 0.75 |
| 10 | 0.6 | 1.5 | ||
| 15 | 0.9 | 2.25 | ||
| 20 | 1.2 | 3 | ||
| 30 | 1.8 | 4.5 | ||
| 50 | 3 | 7.5 | ||
| 75 | 4.5 | 11.25 | ||
| 100 | 6.5 | 16.25 | ||
| 150 | 10 | 25 | ||
| 200 | 13 | 32.5 | ||
| 300 | 20 | 50 | ||
| 400 | 26 | 65 | ||
| 500 | 15/15 | 32.5 | 82 | |
| 600 | 40 | 100 |
Installation & Wiring
Installation Diagram
The LDJ-10/210-L(Y) current transformer is designed for installation in KYN handcart-type switchgear. It features an indoor epoxy resin cast fully enclosed through-type structure with a single terminal/contact box for primary terminals P1/P2. Mounting dimensions, primary terminal box location, phase-to-ground clearance, and handcart compatibility must be verified against the approved outline drawing before cabinet design or batch production.
Wiring Diagram
Primary terminals are marked P1 and P2, with current flowing from P1 to P2. Secondary terminals are labeled 1S1/1S2 for the first core and optionally 2S1/2S2 for a second core, depending on the secondary configuration. All connections must follow the project wiring diagram and terminal markings. Ensure correct polarity and secure connections to prevent measurement errors or protection malfunctions.
Selection & FAQs
Selection Guide
- Confirm the KYN handcart mechanical interface first. Specify LDJ-10Q or the exact LDJ-10/210-L(Y) layout, then verify the primary terminal/contact box, handcart position, phase spacing, mounting points and cabinet clearances.
- Separate standard table ratios from special high-current versions. Detailed published fault data covers 5A–600A; ratings up to 1250A and proposed 1500A–3150A versions require a model-specific drawing and technical confirmation.
- Select metering and protection classes by circuit duty. Measurement options include 0.2S, 0.2, 0.5S and 0.5, while the ratio table lists both 5P10 and 10P10 protection choices. State each core explicitly.
- Choose secondary current and burden together. Standard 1A or 5A options and 10VA–25VA outputs vary by ratio and winding configuration; 2A is a special option and must be confirmed with all connected equipment.
- Verify insulation, environment and fault withstand. Confirm 12/42/75kV coordination, creepage above 530mm, altitude, ambient temperature and the ratio-specific 1-second thermal and dynamic current ratings.
Frequently Asked Questions
Q1: Can these CTs be installed in 11kV KYN switchgear?
Yes, they are designed for 10kV, 11kV, and 12kV indoor switchgear. They feature epoxy resin casting with a 12/42/75kV insulation level. Confirm exact system voltage with our engineering team.
Q2: Which accuracy class combination is best for protective relaying?
Select 5P10 or 10P10 classes for protection circuits to ensure reliable fault detection. These classes maintain accuracy during high short-circuit currents up to the rated thermal limit. Specify your exact burden requirements during ordering.
Q3: How do I verify the short-circuit withstand capability?
Refer to the rated short-time thermal and dynamic current values in the technical table for your primary rating. For instance, a 10A primary supports 0.6kA thermal and 1.5kA dynamic currents. Request the full test report for validation.
Q4: Can the secondary current be customized to 2A instead of 1A or 5A?
Yes, a 2A secondary current is available by special request. Standard options include 1A or 5A secondary outputs compliant with IEC 61869-2. Please specify your custom requirement in the initial inquiry.
Q5: What factory tests are performed before shipment?
All units undergo standard routine tests per IEC 61869-1/-2, including insulation resistance and ratio verification. Type test certificates are available upon request for project documentation. Contact our sales team for specific test documentation requirements.
Q6: Are these current transformers suitable for outdoor medium-voltage applications?
No, the LDJ-10Q and LDJ-10/210-L(Y) models are strictly designed for indoor medium-voltage switchgear. They operate within a -5°C to +40°C ambient temperature range at altitudes up to 1000m. For outdoor needs, contact us for alternative models.