Overview
The JLSZW series outdoor epoxy resin cast combined instrument transformers integrate voltage and current measurement, energy metering, and relay protection in a single compact unit for 10kV to 35kV AC power systems. Designed for outdoor substations and industrial distribution networks, these units deliver galvanically isolated secondary signals using electromagnetic induction principles at 50 Hz frequency.
Featuring a fully sealed pillar-type structure with UV-resistant epoxy casting, the JLSZW ensures long-term reliability in harsh environments while supporting revenue-grade metering and comprehensive protection schemes through standardized VT and CT outputs.
Key Ratings Snapshot
| Parameter | Value |
|---|---|
| System Voltage Class | 10kV / 12kV / 35kV |
| Rated Frequency | 50 Hz (60 Hz on request) |
| Configuration | Combined VT + CT unit |
| VT Connection | V/V (standard); Y/Y (upgrade) |
| CT Phases | A-phase and C-phase (V/V) |
| Rated Secondary Current | 1 A or 5 A (tap-adjustable) |
| Accuracy Classes | VT: 0.2 / 0.5; CT: 0.2S / 0.5 (metering), 10P (protection) |
| Built-in Metering | Active & reactive energy meters |
| Insulation Structure | Epoxy resin cast, fully sealed |
| Lightning Protection | ZnO arrester within 1 m required |
Model Designation
- J: Combined instrument transformer (VT + CT integrated unit)
- L: Current transformer component
- S: Three-phase configuration
- Z: Outdoor support (pillar) type structure
- W: Outdoor application / weatherproof enclosure
- 6 / 10 / 35: Voltage class (kV): 6kV, 10kV, or 35kV systems
Construction
The JLSZW features an outdoor pillar-type, fully sealed epoxy resin cast enclosure that integrates both voltage and current transformers into a single robust housing. This design provides superior insulation performance, excellent resistance to UV radiation, moisture, pollution, and aging, ensuring stable operation with minimal maintenance over extended service life in demanding outdoor conditions.
Advanced epoxy casting technology prevents ingress of dust, water, and contaminants while offering high dielectric strength and anti-tracking surface properties. The unit includes ring-type CT cores, laminated VT cores, weatherproof secondary terminals, and protected compartments for integrated active and reactive energy meters.
Technical Parameters
Service Conditions
- Installation environment: Outdoor substations and distribution networks
- Altitude: <= 1000 m (higher requires derating)
- Ambient temperature: -25 deg C to +40 deg C
- Relative humidity: Daily average <= 95%, monthly average <= 90%
- Pollution severity: Up to level III per IEC 60815
- Environmental exposure: Rain, snow, ice, solar radiation, atmospheric contamination
- Seismic resistance: Intensity VII (customizable)
- Wind load: Suitable for typical regional conditions
Technical Data
| Voltage Class |
VT Primary Voltage |
VT Secondary Voltage |
Accuracy Class |
Rated Burden (VA) |
Rated Primary Current (A) |
CT Ratio | CT Accuracy (Metering / Protection) |
Ith (1s) (kA) |
|---|---|---|---|---|---|---|---|---|
| 6/10 kV | 6000/10000 V | 100 V or 100/√3 V | 0.2 / 0.5 | 50-200 | 5-600 | Tap-adjustable | 0.2S / 10P10 | 20-60 |
| 12 kV | 12000 V | 100 V or 100/√3 V | 0.2 / 0.5 | 50-200 | 10-800 | Tap-adjustable | 0.5 / 10P15 | 20-75 |
| 35 kV | 35000 V | 100 V or 100/√3 V | 0.2 / 0.5 | 50-200 | 10-800 | Tap-adjustable | 0.5 / 10P15 | 20-75 |
Installation & Wiring
Installation Diagram
The JLSZW combined transformer is mounted on a concrete foundation or steel structure using designated anchor points. Primary connections are made via overhead line terminals or busbars, while secondary wiring is routed through weatherproof cable gland entries. Adequate clearance must be maintained for insulation, safety, and maintenance access. Zinc oxide surge arresters must be installed within 1 meter of primary terminals.
Outline Dimensions
| Model | Total Height (mm) | Base Width (mm) | Mounting Hole Spacing (mm) | Primary Terminal Height (mm) |
|---|---|---|---|---|
| JLSZW-10kV | 1250 | 320 | 280 | 1100 |
| JLSZW-35kV | 1850 | 420 | 360 | 1650 |
Selection & FAQs
Selection Guide
- Choose V/V connection for standard three-phase three-wire systems with two-element metering; select Y/Y for unbalanced loads or neutral monitoring needs.
- Specify VT accuracy class 0.2 or 0.5 and CT class 0.2S for revenue-grade metering; use 10P10/10P15 for protection cores.
- Confirm rated burden (VA) for each VT and CT core based on connected instrument loads to avoid accuracy degradation.
- Ensure ambient temperature, altitude, pollution level, and seismic zone match standard ratings or request custom engineering confirmation.
- Always include zinc oxide surge arrester within 1 m of primary terminals for effective lightning protection coordination.
- Verify secondary current preference (1 A or 5 A) and communication interface (e.g., RS485/Modbus) for integrated meters during ordering.
Frequently Asked Questions
Q1: What outdoor environments can this combined transformer withstand?
It operates in IEC pollution level III environments with temperatures from -25°C to +40°C. The epoxy resin casting resists rain, snow, and solar radiation. Contact us for extreme altitude requirements.
Q2: Which accuracy class is suitable for protective relaying?
Select the 10P10 accuracy class for protection applications. This ensures reliable performance during fault conditions up to the rated short-circuit current. Confirm your specific burden requirements with our engineering team.
Q3: How is the short-circuit current rating specified?
The thermal short-circuit current (Ith) ranges from 20 kA to 60 kA for a 1-second duration. Specify your exact system fault level during ordering. Factory verification is required for higher ratings.
Q4: Can the current transformer ratio be adjusted on-site?
Yes, the CT ratio is tap-adjustable to match primary current needs from 5A to 800A. Specify your required tap settings during procurement. Final calibration is performed at the factory.
Q5: Are specific factory tests performed before shipment?
Standard routine tests include ratio, polarity, insulation resistance, and withstand voltage measurements. Special type tests are available upon request. Request the specific test certificate format required for your project.
Q6: Where is this epoxy resin combined transformer typically installed?
It is designed for outdoor substations and distribution networks up to 12 kV. The combined VT and CT design saves installation space. Contact our sales team for project-specific application engineering.
Q7: Is high-altitude installation supported for this 12kV model?
Standard models are rated for altitudes up to 1000 meters. Installations above this level require capacity derating. Provide your exact site altitude for factory engineering evaluation.