Rockwill Ukraine 186 Units 12kV Outdoor Vacuum Recloser Project Success Case

In response to the operational characteristics of Ukraine’s local power grid and targeting harsh high-latitude outdoor working conditions, we rely on core technologies of intelligent reclosing and self-healing to precisely adapt to the complex grid environment with frequent thunderstorms and drastic diurnal temperature variations, steadily promoting the automatic and intelligent upgrade of regional rural power grids and suburban distribution networks.

01 Project Overview

1.1 Project Background

In 2021, 186 units of 12kV outdoor vacuum reclosers, developed and manufactured by Rockwill, were officially supplied and commissioned for the Ukraine medium-voltage distribution grid upgrade project. These devices are primarily used to enhance fault isolation, rapid reclosure capabilities, and power supply reliability. Currently, the equipment is operational across urban and rural distribution lines in south-central Ukraine, earning high recognition from DTEK Dnieper Electric Networks, a leading Ukrainian energy utility.

The outdoor vacuum recloser is a core protection and automation component for Ukraine's 12kV (adapted for the local 10kV system) distribution network. It automatically restores power during transient faults (such as lightning strikes or wind-induced contact) and rapidly isolates permanent fault sections. This project addresses long-standing issues in the region, such as frequent faults and high maintenance costs. Integrated with Feeder Terminal Units (FTU), these reclosers withstand extreme temperatures from -40°C to +50°C and heavy dust, accelerating the automation and intelligence of the Ukrainian power grid.

1.2 Technical Parameters

02 Product Manufacturing

2.1 Insulation System

The reclosers feature a high-performance outdoor insulation structure. The primary insulation components utilize high-grade silicone rubber composite materials, providing excellent resistance to UV, tracking, and low temperatures. This ensures long-term operation without insulation risks under Ukraine's harsh winter and lightning-prone summer conditions.

2.2 Operating Mechanism

Equipped with a high-reliability permanent magnet mechanism, the device offers precise action, rapid response, and extended mechanical life. It supports up to 0-3 automatic reclosure cycles. Combined with the FTU, it significantly enhances fault processing speed and grid self-healing capabilities.

2.3 Controller and Smart Modules

The integrated smart controller monitors real-time line current and voltage to distinguish between transient and permanent faults. It supports seamless integration into the DTEK SCADA system. The FTU supports multiple protection setting groups and built-in ANSI/IEC standard TCC curves, ensuring perfect time-current coordination with substation breakers and downstream sectionalyzers.

2.4 Enclosure and Anti-corrosion

The main switch tank is constructed from high-strength stainless steel with a fully sealed design (IP67 rating). The FTU control box utilizes double-layered stainless steel (IP55 rating) with anti-condensation features. This design extends service life and reduces maintenance costs in dust-heavy agricultural areas.

03 Factory Acceptance Testing (FAT)

All 186 units passed comprehensive type tests and factory tests in accordance with DSTU (Ukrainian National Standards) and IEC 62271-111(https://webstore.iec.ch/en/publication/28088) international standards:

• Insulation Tests: Verified withstand levels for 12kV systems to resist lightning-induced surges.
• Contact Resistance Test: Ensured low heat dissipation for long-term outdoor operation.
• Mechanical Characterization: Verified opening/closing times. The controller is equipped with automatic heating components and low-temp storage capacitors to ensure precise operation at -40°C.
• Line Protection Function Test: Simulate all types of line conditions such as phase-to-phase short circuit, single-phase grounding, power direction, and closing on fault, to rigorously verify the action logic and reliability of core functions including 79 automatic reclosing, 50/51P phase overcurrent, 50/51G/N ground overcurrent, 50SEF sensitive ground fault, 50/67P/G directional protection, 27/59 over/undervoltage, 46 negative sequence overcurrent, and voltage unbalance protection. Ensure the protection device can accurately identify faults and operate reliably within milliseconds, without any mal-operation or failure to operate, to fully guarantee the safe and stable operation of distribution lines.

• Environmental Adaptability Check: Simulate extreme high and low temperatures, high humidity and dusty environments in Ukraine to ensure the equipment can operate stably for a long time under complex outdoor conditions.

04 Logistics and Execution

The units were secured in export-grade wooden crates with moisture-proof vacuum lining to endure long-distance sea and inland transport. Rockwill’s dedicated logistics team tracked the shipment to ensure the construction schedule remained on track.

05 Installation and Operational Summary

5.1 Field Implementation

• Site Preparation: In alignment with Ukrainian 10kV distribution standards and on-site pole specifications, foundation work, mounting point fixation, and cable conduit pre-treatment were completed to accommodate local double-pole installation regulations.
• Equipment Hoisting: Utilized professional lifting equipment to securely hoist and fix the reclosers to designated positions, ensuring structural integrity against local high-wind load conditions.
• Wiring and Connectivity: Executed HV and control cable terminations strictly according to engineering drawings. Conducted rigorous inspections of connection tightness, insulation integrity, and grounding reliability to eliminate safety hazards.
• On-site Commissioning: Performed energized debugging by simulating various fault scenarios, including lightning strikes and line short-circuits. Verified protection relay actions, reclosure logic, and remote communication functionality. All units were formally integrated into the grid after passing final acceptance.
• Technical Training: Organized specialized sessions for DTEK maintenance teams, covering equipment operating principles, commissioning techniques, troubleshooting methodologies, and SCADA system integration to enhance local operational autonomy.

5.2 Operational Feedback

Since the commissioning of the 186 units of 12kV outdoor vacuum reclosers, the system has demonstrated exceptional stability with zero quality-related failures. All performance metrics have met or exceeded design requirements, earning high accolades from DTEK Dnieper Electric Networks and local end-users:

• 118 Successful Auto-reclosures: Rapidly cleared a significant number of transient faults, preventing unplanned outages for residential areas, agricultural irrigation, and SME industrial users, thus safeguarding local productivity.
• 9 Permanent Faults Isolated: Precisely located and isolated permanent fault sections, preventing fault propagation and confining the outage impact to the smallest possible zone.
• 180 Hours Downtime Saved: Significantly improved the overall System Average Interruption Duration Index (SAIDI) for the south-central Ukrainian distribution network, enhancing user satisfaction.
• 42 Hours Maintenance Time Saved: Reduced the labor intensity for manual line inspections and fault locating, optimizing O&M efficiency and alleviating the pressure of limited local maintenance resources.

06 Life-cycle O&M Services

Rockwill provides integrated life-cycle maintenance for the Ukraine project, utilizing a Condition-Based Maintenance (CBM) model. This covers everything from installation and monitoring to state assessment and eventual decommissioning.

This project demonstrates Rockwill’s capability in medium-voltage distribution automation and overseas localized services. Contact us today to customize your mature distribution automation solutions!