84 Units 33kV Outdoor SF6 Load Break Switches for Tanzania White City Power Project
Rockwill has successfully delivered 84 units of 33kV outdoor SF6 load break disconnectors. The equipment has been officially commissioned and connected to the grid for operation in the White City Power Project of Tanzania REA Phase II, empowering the upgrading and improvement of rural power grids in Tanzania.
01 General Overview: Tanzania White City 33 kV Grid Upgrade Project
1.1 Project Background
The Phase II project (REA II) of the Tanzania Rural Energy Agency (REA) is one of the largest rural electrification initiatives in East Africa. It aims to improve electricity coverage and stability in remote areas by upgrading the 33 kV distribution network. The distribution lines in White City span a typical tropical savanna climate zone, facing challenges such as extreme high temperatures (exceeding 45°C), intense UV radiation, humidity fluctuations during alternating dry and wet seasons, and high dust environments.
To address these challenges, Rockwill delivered 84 units of 33 kV outdoor SF6 gas-insulated load break switches (LBS). These devices are integrated with motorized operating mechanisms and SCADA monitoring systems. Through line segmentation, isolation, and automated dispatching, they effectively resolve the long-term power outage issues caused by manual fault patrolling on long-distance distribution lines.
1.2 Technical Specifications
The equipment used in this project adheres to strict international standards for electrical performance and environmental resistance:
| Parameter | Specification |
|---|---|
| Equipment Type | Outdoor SF6 Insulated Load Break Switch (LBS) |
| Rated Voltage | 33 kV |
| Rated Continuous Current | 630 A |
| Rated Frequency | 50/60 Hz |
| Short Time Withstand Current | 20 kA / 3s |
| Rated Short-circuit Making Current | 50 kA (Peak) |
| Mechanical Operations | 10,000 times (Guaranteed) |
| Mechanism Type | Motorized with backup manual handle |
| Compliance Standards | IEC 62271-103, IEC 62271-1:2017 |
1.3 Core Value
The project solution implements a "segmentation + automated operation" logic to achieve an intelligent upgrade of the Tanzania REA II lines:
- Line Segmentation: 84 nodes provide fine-grained segmentation on long-distance lines, minimizing the scope of power outages.
- Flexible Load Switching: Supports frequent switching under a 630 A rated current, facilitating grid interconnection and capacity expansion.
- Fault Current Handling: 50 kA short-circuit making capability ensures perfect coordination with upstream protection devices.
02 Manufacturing Quality: Reliability for Tropical Environments
2.1 SF6 Gas Insulation Technology
To counter the risks of high dust and humidity in the tropical savanna climate, Rockwill utilizes a fully sealed stainless steel enclosure. SF6 gas, as the insulation and arc-extinguishing medium, provides excellent dielectric properties, reducing the equipment volume by 40% compared to air-insulated alternatives. The internal contacts are completely shielded from external salt spray and moisture corrosion.
2.2 Motorized & SCADA Ready
- Intelligent Upgrade: Each unit is equipped with a high-reliability motorized mechanism, supporting remote signal triggering with millisecond-level response times.
- Real-time Monitoring: Reserved SCADA communication interfaces allow the dispatch center to obtain real-time load status, SF6 pressure alarms, and switch position signals, moving away from passive "manual patrol" maintenance modes.
2.3 Superior Corrosion & UV Protection
- Enclosure Material: Made of 304/316L grade stainless steel with a specialized powder coating process, ensuring corrosion resistance far exceeding conventional outdoor switches.
- Seal Optimization: Designed for Africa's intense UV environment, all external seals are made of high-performance silicone rubber and UV-resistant materials, ensuring no cracking or leakage throughout the 30-year lifecycle.
03 Rigorous Testing: Compliance with International Standards
Rockwill maintains "engineering-grade" quality control. Before delivery, all 84 units passed comprehensive type tests in authoritative third-party laboratories:
- Insulation Test: Verified power frequency and lightning impulse withstand levels under simulated high-temperature and high-humidity conditions.
- Temperature Rise Test: Ensured that winding temperature rise remains within standards under a 45°C ambient temperature and 630 A full-load operation.
- Short-time Withstand & Peak Current Test: Verified mechanical stability under 20 kA / 3s and 50 kA peak conditions.
Routine Factory Tests:
- SF6 Leakage Detection: High-precision helium mass spectrometer leak detectors ensure an annual leakage rate of less than 0.1%.
- Mechanical Operation Alignment: 100% execution of 50 consecutive motorized operations to verify mechanism reliability.
- Contact Resistance Measurement: Strict control of contact resistance to reduce operational losses.
04 Logistics & Delivery: Secure Cross-regional Transport
4.1 Professional Packing
For long-distance inland transport in Tanzania, the equipment is packed in heavy-duty fumigated wooden cases, equipped with internal shock absorbers and vacuum plastic sealing to protect precision motorized mechanisms from damage during bumpy transport.
4.2 Timely Delivery
Rockwill's overseas project support team ensured that the 84 units were delivered to the White City site in batches, effectively safeguarding the overall progress of the REA II project.
05 Site Performance & Lifecycle Value
5.1 Installation Performance
Thanks to the highly integrated pole-mounted design, the site construction team achieved "plug-and-play" installation. Standardized terminals and clear control cabinet interfaces significantly shortened the on-site commissioning cycle.
5.2 Summary
The successful commissioning of the Tanzania White City project demonstrates the superior reliability of Rockwill SF6 load break switches in harsh tropical environments. Through SCADA integration, the average fault recovery time in the region has been reduced by approximately 50%, providing a successful model for the intelligent transformation of East African power grids.
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