Overview
The JLSW3-10 is an outdoor oil-immersed three-phase combined instrument transformer integrating voltage and current measurement in a single compact unit. Designed for 10 kV AC power systems, it delivers high-accuracy metering (0.2/0.2S) and reliable relay protection performance in harsh outdoor environments. Its fully insulated Y/Y-connected PTs and electromagnetic CTs ensure precise proportional signal conversion for energy billing and system monitoring.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| System voltage class | 10 kV (6 kV variant available) |
| Rated frequency | 50 Hz / 60 Hz |
| PT configuration | 3 x single-phase, Y/Y connection |
| CT configuration | 3 x electromagnetic type (A, B, C phases) |
| Metering accuracy class | 0.2 / 0.2S |
| Insulation structure | Oil-immersed with moisture-prevention device |
| Installation type | Outdoor |
| Lightning protection | ZnO surge arrester required within 1 m |
| Secondary terminals (CT) | 1S1/1S2 (metering), 2S1/2S2 (protection, if specified) |
| Grounding | Dedicated bolt on tank cover |
Model Designation
- J: Combined instrument transformer (metering unit)
- L: Current transformer component included
- S: Voltage transformer (PT) component included
- W: Outdoor installation type
- 3: Three-phase configuration (A-B-C phases)
- 10: Voltage class (kV)
Construction
The JLSW3-10 features a robust square oil tank engineered for outdoor durability. All six transformer elementsâthree single-phase fully-insulated voltage transformers and three electromagnetic current transformersâare securely mounted on the tank base plate and sealed within the oil-filled enclosure. The oil provides excellent dielectric strength and thermal dissipation, while the integrated moisture-prevention device on the tank cover blocks external humidity ingress, significantly enhancing service life in exposed environments.
The tank cover includes practical features such as lifting lugs for transport, an oil level gauge for maintenance monitoring, a grounding bolt for safety compliance, and a drain valve for servicing. This compact, lightweight design simplifies field installation compared to traditional separate PT and CT setups, making it ideal for space-constrained outdoor distribution applications.
Technical Parameters
Service Conditions
- Installation: Outdoor (substations, industrial sites, primary metering points)
- Altitude: <=1000 m standard; higher on request
- Temperature: Per GB outdoor oil-immersed limits; extremes to be specified
- Humidity: Outdoor moisture-proof/breather protected
- Site condition: Non-corrosive, non-explosive, low vibration/impact
- Lightning: ZnO arrester required within 1 m of unit
Technical Data
| Parameter | JLSW3-6 | JLSW3-10 |
|---|---|---|
| System voltage class | 6 kV | 10 kV |
| Rated frequency | 50 Hz / 60 Hz | 50 Hz / 60 Hz |
| PT configuration | 3 x single-phase Y/Y connection |
3 x single-phase Y/Y connection |
| CT configuration | 3 x electromagnetic type | 3 x electromagnetic type |
| Metering accuracy class | 0.2 / 0.2S | 0.2 / 0.2S |
| PT transformation ratio | Per specification (customizable) |
Per specification (customizable) |
| CT transformation ratio | Per specification (customizable) |
Per specification (customizable) |
| Secondary output (PT/CT) | Per specification (VA) | Per specification (VA) |
| Insulation structure | Oil-immersed with moisture prevention |
Oil-immersed with moisture prevention |
| Installation | Outdoor | Outdoor |
Installation & Wiring
Installation Diagram
The JLSW3-10 must be securely mounted using the base provisions, with primary connections made according to terminal markings and wiring diagrams. Maintain adequate clearance for insulation, heat dissipation, oil level monitoring, and maintenance access. A zinc oxide surge arrester must be installed within 1 meter of the unit for effective lightning protection. Before energization, remove the unsealed breather element from the central buffer rubber of the moisture-prevention device.
Outline Dimensions
| Dimension | Value (mm) |
|---|---|
| Height (H) | As per dimensional drawing |
| Width (W) | As per dimensional drawing |
| Depth (D) | As per dimensional drawing |
| Mounting hole pattern | Per base plate specification |
| Primary terminal height | Per phase arrangement |
Selection & FAQs
Selection Guide
- Specify system voltage class (6 kV or 10 kV) based on grid requirements.
- Select PT and CT transformation ratios to match metering and protection device inputs.
- Choose accuracy class (0.2 or 0.2S) per local utility revenue-metering standards.
- Define rated burden (VA) for each secondary winding to ensure performance under load.
- Confirm outdoor environmental conditions (altitude, temperature, pollution) for proper insulation rating.
- Indicate if protection cores, special terminals, or integrated meter housing are needed.
Frequently Asked Questions
Q1: How should this combined transformer handle lightning protection?
A ZnO surge arrester must be installed within 1 meter of the unit. This ensures adequate protection for the 10kV outdoor oil-immersed system. Contact our engineering team for specific arrester sizing.
Q2: Which accuracy class is available for revenue metering?
The JLSW3-10 offers 0.2 and 0.2S accuracy classes for precise metering. These classes guarantee high precision for billing applications across 6kV and 10kV systems. Specify your exact ratio requirements during ordering.
Q3: Can the PT and CT configurations be customized?
Yes, both potential and current transformer ratios are fully customizable per your specification. The standard setup uses three single-phase Y/Y connected PTs and electromagnetic CTs. Submit your technical drawings for factory confirmation.
Q4: What routine factory tests are conducted before dispatch?
Standard electrical and insulation tests are performed to verify compliance with GB outdoor limits. Specific test certificates and detailed reports are subject to confirmation. Please contact our sales team for the exact test scope.
Q5: Is factory certification provided with the standard shipment?
Basic factory compliance documents are provided to verify adherence to GB outdoor limits. Specific international certification requirements are subject to confirmation. Please contact our sales team to discuss your exact documentation needs.
Q6: Do the CTs withstand high short-circuit thermal stresses?
The electromagnetic CTs are designed to withstand high short-circuit thermal and dynamic stresses. Exact short-circuit withstand levels depend on the specific transformation ratio. Submit your system fault level data for factory verification.
Q7: Are these 10kV combined transformers manufactured to IEC standards?
The JLSW3 series is designed according to GB standards for outdoor oil-immersed equipment. IEC compliance or other international standards are subject to confirmation. Contact our engineering department for specific standard requirements.