Urban distribution networks. Load density is high and power quality expectations are strict. A transient fault that is not cleared quickly interrupts commercial activity and household supply in dense areas.
Rural extension lines. Supply radii are long and the number of laterals is high. These lines are exposed to tree contact and lightning induced earth faults, and locating a fault by manual line patrol is slow and labor-intensive.
Industrial supply. Continuous supply matters most here. Unwanted operation, or failure to operate, in conventional protection equipment can stop a production line and cause significant financial loss.
Rockwill, a smart recloser China manufacturer, based the solution on two requirements: high operational reliability, and genuine adaptation to the local environment. The RCW12M is an outdoor, pole-mounted automatic circuit recloser built around four subsystems.
The controller compares measured line current and voltage against the configured protection settings. The sequence is as follows.
Because the protection characteristic and the reclosing sequence are both settable, the recloser can be graded accurately against the upstream 33/11 kV substation protection. A fault on one feeder is therefore cleared locally rather than escalating to the substation breaker.
3. Engineering documentation
The project was supported by a complete set of drawings for the RCW12M 11 kV auto recloser. The documentation covers the primary circuit, secondary control, protection logic and communication interfaces, and matches the Kenyan network requirements of 50 Hz operation and a 175 V to 300 V control supply. Connection and control logic for the magnetic actuator, voltage sensors and the remote control interface are clearly identified on the drawings, giving site teams the basis for installation, commissioning and maintenance.
Before shipment, all 720 units completed factory testing covering the following items.
Test Purpose Dielectric withstand test Verifies the insulation performance of the poles and insulation components at rated and impulse voltage levels Main circuit resistance test Verifies conductor and contact performance, keeping conduction losses and temperature rise within limits Mechanical characteristic test Checks opening and closing times, pole simultaneity and mechanical endurance to confirm stable actuator operation Functional and logic test Simulates network fault conditions to verify reclosing, lockout and protection operation
Because every unit was delivered fully tested and functionally verified, site work was limited to lifting into position, cable termination, terminal torque checks and energization verification of the protection and reclosing logic.
Packaging and shipping. The 720 units were packed for export in moisture-proof, shock-absorbing packing, with an internal moisture barrier and an externally reinforced timber crate, suitable for long sea freight. All units arrived at the Kenyan port complete and were delivered to the project schedule.
5. Installation, commissioning and training
Installation followed a short, repeatable sequence at each site.
6. Commercial value: total cost of ownership
6.1 Capital expenditure
Right-sized specification. The 630 A and 16 kA ratings were matched to the measured duty of the Kenyan medium voltage network, which avoids the cost of over-specified equipment. The 720-unit volume also benefits from Rockwill's manufacturing scale.
Build-to-specification supply. For projects that require a vacuum recloser customized OEM build, the RCW12M platform can be adapted in rated current, short-circuit breaking capacity, control functions and interface details without changing the installation concept or the commissioning routine.
Standard interfaces. The standard product interface allows the reclosers to integrate with existing 33 kV substation systems without custom adapters or bespoke interface components.
Reduced site effort. Factory pre-commissioning and a delivery model based on factory-tested units and site assembly reduced installation and commissioning time per unit by more than 80 percent compared with conventional site-based commissioning, based on project experience across the 720-unit fleet. That directly reduces local labor cost and construction plant hire.
6.2 Operating expenditure
Verified low conduction losses. Every unit passed the main circuit resistance test before shipment, which keeps contact resistance, conduction losses and operating temperature low over the service life.
Condition-based maintenance. The controller supports remote communication and status upload. Maintenance teams monitor equipment health through SCADA and move from fixed-interval inspection to condition-based intervention, which reduces unnecessary site visits and travel.
Fault response cost. Automatic clearing and restoration removes the cost of a manual restoration visit for most transient faults. For a fleet of 720 units across long rural feeders, the avoided travel and labor is a significant recurring saving.
Long-term asset value. Combined with lifecycle maintenance and local training, the recloser fleet retains its reliability over a longer service life, reducing both emergency repair cost and outage cost.
7. Project results and customer feedback for the 720-unit auto recloser fleet
After energization, the 720 RCW12M 11 kV auto reclosers have operated without equipment failure, with stable operating status across the installed base. The project has raised supply reliability on the Kenyan medium voltage network and has been received positively by the Kenyan power utility and by end users, who also noted the responsiveness and quality of after-sales support.
The project demonstrates the development, manufacturing and delivery capability of Wenzhou Rockwill Electric, an auto recloser China manufacturer, and stands as a reference delivery for distribution network upgrades in Africa.
8. Lifecycle operation and maintenance managed service
Rockwill provides a managed lifecycle service covering oil-immersed transformers, dry-type transformers, switchgear, ring main units, vacuum circuit breakers, reclosers, pole-mounted switches, reactive power compensation devices and distribution automation terminals. The service runs from selection and matching, through installation and commissioning, condition monitoring, periodic inspection, maintenance, fault repair and condition assessment, to decommissioning and disposal.
Each contract is managed by a named owner with full process control, traceable data and closed loop management, so equipment stays safe and available, service life is extended and operating cost is reduced. The service applies to all voltage levels and distribution scenarios.
Contact Rockwill
If you are working to improve supply reliability or reduce maintenance cost on a medium voltage distribution network, Rockwill can support the full scope.
Rockwill builds to IEC standards and applies intelligent technology to strengthen power networks in Africa. We look forward to working with you.
