Overview
The LDC(D)-10 and LMC(D)-10 are indoor wall-through type current transformers designed for 10kV, 11kV, and 12kV medium-voltage AC power systems. These cast-resin insulated transformers feature a compact structure suitable for switchgear integration, with primary conductors passing through the transformer body or connected via bus-type configurations.
They support metering accuracy classes of 0.5, 1, and 3, as well as protection class 10P, making them suitable for current measurement, energy metering, signal sampling, relay protection, and microcomputer-based protection applications. The design complies with IEC 61869-1 and IEC 61869-2 standards, with insulation coordination rated at 12/42/75kV for reliable operation in IEC 12kV-class systems.
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 (standard), 1A (optional) |
| Metering accuracy classes | 0.5, 1, 3 |
| Protection accuracy class | 10P |
| Primary current range | Up to 5000A |
| Application | Measurement, metering, protection |
| Installation type | Indoor wall-through / bus-type |
| Standards | IEC 61869-1, IEC 61869-2 |
| Insulation material | Cast-resin |
Model Designation
- L: Current transformer
- D: Wall-through / special indoor switchgear structure
- M: Bus type structure
- C: Wall-through insulation structure according to model series
- D in brackets: Differential protection version or protection-oriented configuration
- Q: Enhanced or special structural version according to project configuration
- 10: Voltage class identification; used for 10kV systems and IEC 12kV-class insulation coordination for 10kV, 11kV, and 12kV projects
Construction
The LDC(D)-10 and LMC(D)-10 current transformers are constructed with a cast-resin insulation system, providing high dielectric strength and mechanical stability for indoor medium-voltage environments. The core and windings are fully encapsulated in epoxy resin, ensuring moisture resistance, thermal endurance, and long-term operational reliability. The wall-through design allows the primary conductor to pass directly through the transformer body, while maintaining electrical separation between the medium-voltage primary circuit and the low-voltage secondary circuit. The compact form factor facilitates easy installation in switchgear panels and distribution cabinets, with robust terminal blocks for secure secondary connections. This construction meets the requirements for both metering and protection applications under IEC standards.
Technical Parameters
Service Conditions
- Installation location: indoor medium-voltage switchgear or wall-through panel
- System voltage: 10kV, 11kV, or 12kV class
- Rated frequency: 50Hz / 60Hz
- Rated insulation level: 12/42/75kV reference for IEC-style 12kV-class projects
- Ambient temperature: -5°C to +40°C reference range
- Humidity and pollution conditions: Suitable for indoor switchgear with controlled humidity, pollution, and condensation conditions
- Environmental restrictions: The installation site should be free from severe vibration, corrosive gas, explosive medium, heavy conductive dust, and abnormal condensation.
- High-current considerations: For high-current busbar applications, heat dissipation, clearance, and mechanical fixing must be confirmed with the switchgear design.
Technical Parameters
The LDC(D)-10 and LMC(D)-10 are cast-resin indoor wall-through type current transformers designed for 10kV to 12kV medium-voltage systems. They feature a rated insulation level of 12/42/75kV, operate within an ambient temperature range of -5°C to +40°C, and comply with IEC 61869-1 and IEC 61869-2 standards. Primary current ratings span from 400A to 5000A depending on model variant.
Current transformers are in accordance with the Chinese Standard GB 1208-75.
| Parameter | Value |
|---|---|
| Rated Primary Current (A) | 200, 3000, 4000, 5000 |
| Rated Secondary Current (A) | 5 |
| Frequency (Hz) | 50 |
| Rated Output (VA) for Accuracy Class 0.5 | 10 |
| Rated Output (VA) for Accuracy Class B | 15 |
| Insulation Level (kV) | 10/42/75 |
| Rated Short-Time Thermal Current Ith (kA) | 75 I1n |
| Rated Dynamic Current Idyn (kA) | 2.5 Ith |
| 10% Multiple | 10 |
Installation & Wiring
Installation Diagram
The LDC(D)-10 and LMC(D)-10 series are installed as indoor wall-through or bus-type current transformers within switchgear. Mounting is performed according to the approved outline drawing, ensuring proper alignment of the primary conductor, secondary terminal box orientation, and interface with the switchgear panel.
Selection & FAQs
Selection Guide
- Choose the structural family before selecting the ratio. LDC/LDCQ variants are listed mainly for 400A–1500A wall-through duties, while LMC variants serve 2000A–5000A high-current bus systems; confirm the exact outline for each suffix.
- Specify both secondary winding functions. Measurement combinations include 0.5/0.5, 1/1 and 0.5/3, while D versions add 10P measurement/protection or 10P/10P arrangements. Define accuracy and output per winding.
- Select the protection class from the relay calculation. References include 10P15 and 10P20 at a 15VA protection burden; verify the required accuracy limit factor and total connected burden rather than selecting only by model code.
- Audit the short-circuit data for the exact variant. The source matrix contains inconsistent thermal and dynamic values, so obtain certified RMS short-time current, duration and peak dynamic current before switchgear fault-duty approval.
- Confirm electrical and mechanical interfaces together. State 1A or 5A secondary, 12/42/75kV insulation, frequency, busbar dimensions, opening, mounting, terminal orientation, heat dissipation, clearances and the applicable standard edition.
Frequently Asked Questions
Q1: What applications suit this wall-through current transformer?
This transformer is designed for indoor medium-voltage switchgear and wall-through panels. It suits 10kV to 12kV systems with primary currents from 400A to 5000A. Contact us for specific project matching.
Q2: How should the installation environment be prepared?
The site must be free from severe vibration, corrosive gases, and heavy conductive dust. Ensure controlled humidity and confirm heat dissipation for high-current busbars. Verify clearances with your switchgear design.
Q3: Which insulation standards does this 12kV CT meet?
It complies with IEC 61869-1 and IEC 61869-2 standards. The rated insulation level is 12/42/75kV for IEC-style 12kV-class projects. Standard test certificates are included with the shipment.
Q4: Can primary current ratings be customized for our project?
Primary current ratings span from 400A to 5000A depending on the model variant. Specific ratio requirements are subject to factory confirmation. Please provide your exact specifications for a tailored quote.
Q5: What factory tests are performed before shipment?
Standard routine tests are conducted according to IEC 61869 and relevant Chinese standards. Detailed test certificates and inspection reports are provided with each delivery. Contact sales for specific testing requirements.
Q6: Are these transformers compatible with 60Hz power systems?
Yes, they are designed for both 50Hz and 60Hz rated frequencies. They operate reliably within the -5°C to +40°C ambient temperature range. Confirm your exact frequency requirement during ordering.
Q7: Why choose a cast-resin wall-through design?
Cast-resin insulation provides excellent dielectric strength and mechanical stability for indoor wall-through applications. It ensures safe integration within 12kV-class medium-voltage switchgear panels. Request technical drawings for dimensional verification.