Overview
The JLS-24/33/35/40.5 is an oil-immersed combined transformer metering box designed for three-phase four-wire high-voltage systems rated at 24kV, 33kV, 35kV, and 40.5kV. It integrates current transformers (CT), voltage transformers (PT), and a watt-hour meter box into a single sealed unit filled with 25# transformer oil and equipped with porcelain bushings for primary and secondary connections.
This device delivers high-accuracy energy measurement suitable for utility revenue metering and industrial substation applications. It complies with GB17201 standards and features anti-theft design elements to ensure billing integrity in outdoor environments such as pole-mounted installations and high-voltage distribution points.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage Class | 24kV / 33kV / 35kV / 40.5kV |
| System Type | Three-phase four-wire |
| Insulation Medium | 25# transformer oil |
| CT Accuracy Class | 0.2S / 0.5S |
| PT Accuracy Class | 0.2 / 0.5 |
| Rated Frequency | 50 Hz |
| Primary Current Range | Customizable per application |
| Secondary Current | 5 A |
| Secondary Voltage | 100 V / 100/√3 V |
| Metering Capability | Active & reactive energy |
| Installation Environment | Outdoor |
| Compliance Standard | GB17201 |
Model Designation
- J: Combined instrument transformer (CT + PT)
- L: Outdoor (pole or substation) installation type
- S: Three-phase four-wire configuration
- 24/33/35/40.5: Rated system voltages in kV
Construction
The JLS-24/33/35/40.5 features a robust oil-immersed construction with a sealed tank filled with 25# transformer oil for insulation and cooling. Primary and secondary terminals are connected via high-quality porcelain bushings that provide reliable performance in harsh outdoor conditions. The integrated watt-hour meter box houses both active and reactive energy meters, ensuring a complete and compact metering solution. The entire assembly is designed for durability, ease of installation, and long-term stability in high-voltage distribution environments.
Technical Parameters
Service Conditions
- Installation position: Outdoor pole-mounted, substation, or distribution points
- Ambient temperature: -25°C to +40°C
- Rated frequency: 50Hz or 60Hz
- Pollution class: IV level
- Insulation: Oil-immersed with 25# transformer oil
- Grounding: Connect grounding terminal per local electrical codes
- Maintenance: Periodic oil level check and meter calibration required
Technical Parameters
The JLS-24/33/35/40.5 is an outdoor oil-immersed combined transformer metering box designed for 24kV, 33kV, 35kV, and 40.5kV systems. It features oil-immersed insulation with 25# transformer oil, operates within a temperature range of -25°C to +40°C, complies with GB17201 standards, and supports current ratios from 5–300/5 A.
Model Variants
| Model | System Voltage |
Voltage Ratio |
Insulation Level(kV) |
Application |
|---|---|---|---|---|
| JLS-24 | 24kV | 24000/100V | 24/50/125 | International 24kV systems |
| JLS-33 | 33kV | 33000/110V | 40.5/95/185 | International 33kV systems |
| JLS-35 | 35kV | 35000/100V | 40.5/95/185 | Chinese standard 35kV systems |
| JLS-40.5 | 40.5kV | 40500/100V | 40.5/95/185 | International 40.5kV systems |
Voltage Transformer Data
| Accuracy Class | Rated Output (VA) | Application |
|---|---|---|
| 0.2 | 50 VA | High-precision metering |
| 0.5 | 25 VA | Standard metering |
Current Transformer Data
| Current Ratio | Accuracy Class | Rated Output |
|---|---|---|
| 5 – 300/5 A | 0.2S | 10 VA |
| 5 – 300/5 A | 0.5S | 10 VA |
Installation & Wiring
Installation Diagram
The JLS-24/33/35/40.5 oil-immersed combined transformer metering box is designed for pole-mounted or pad-mounted outdoor installation. The main unit conforms to standard outdoor metering box dimensions, with a side-mounted compartment for active and reactive energy meters. Porcelain-insulated bushings provide primary and secondary connection points.
Wiring Diagram
Wiring connections must follow the specified terminal markings: primary terminals (AP1, AP2, CP1, CP2) connect to high-voltage lines, while secondary terminals link to the inputs of the meter box. Confirm the correct voltage and current ratios before installation. Ensure all connections are secure and comply with local utility metering requirements.
Selection & FAQs
Selection Guide
- Select the 24kV, 33kV, 35kV, or 40.5kV variant and verify its voltage ratio and insulation level.
- Choose the 5–300/5A CT ratio from the load profile and required metering range.
- Specify CT class 0.2S/0.5S and PT class 0.2/0.5 and calculate all secondary burdens.
- Confirm the three-phase four-wire scheme, active/reactive meters, sealing, anti-tamper, and utility requirements.
- Verify mounting, porcelain clearances, oil access, grounding, pollution class, terminal sequence, and certified drawing.
Frequently Asked Questions
Q1: Which medium voltage systems is the JLS-35 metering box designed for?
It is designed for 35kV systems with a 35000/100V voltage ratio. The insulation level is 40.5/95/185kV, complying with GB17201 standards. Contact us for specific project requirements.
Q2: Can this combined transformer be installed in high pollution areas?
Yes, it features Pollution Class IV insulation suitable for severe outdoor environments. It uses 25# transformer oil for reliable insulation in outdoor pole-mounted or substation applications.
Q3: How are the current ratios configured for this metering box?
The unit supports customizable current ratios ranging from 5/5A to 300/5A. Specify your exact primary and secondary current requirements during the ordering process for factory calibration.
Q4: What routine factory tests are performed before shipping the JLS-24?
Standard routine tests include ratio, polarity, and insulation resistance checks per GB17201. Specific type tests or third-party certifications are subject to confirmation based on your purchase order.
Q5: Can the oil-immersed metering box be customized for 60Hz power grids?
Yes, the transformer supports both 50Hz and 60Hz rated frequencies. Please specify your grid frequency and target delivery schedule during the inquiry for accurate production planning.
Q6: Why choose an oil-immersed combined transformer for 40.5kV outdoor substations?
Oil-immersed designs provide superior heat dissipation and insulation for high-voltage outdoor applications. Our JLS-40.5 model ensures reliable metering in harsh environments with ambient temperatures up to +40°C.
Q7: Are these combined transformer metering boxes suitable for international distribution networks?
Yes, we offer specific models like JLS-24 and JLS-33 for international 24kV and 33kV systems. Verify local electrical codes for grounding and installation compliance with our engineering team.