The Municipality has been experiencing constant outages at the above regions, due to the general condition of the line which has reached a lifespan of 30 years. The walk downs of the 100km overhead network revealed that there are cracked insulators, broken stay wires, cross arms and sagging on the overhead lines. The Municipality has put the following action plan to improve the quality of supply to the 11kV Rural Networks.
Action Plan to Improve the Quality of Supply in the
1. Installation of Fault Path Indicators (FPI)
Fault Path Indicators (FPI) are used for detecting the passage of fault currents in high voltage overhead power lines. The FPI helps to quickly identify in which section of the power line network the fault is located, thereby reducing the outage time. Seventy (70) sets of FPI’s have already been installed and commissioned on the 11kV rural network and an immediate improvement in terms of fault location has already been realized. The gadgets record and send messages directly to the Foreman and other officials as and when a fault is detected on the lines within +/100m accuracy reducing the time spent on patrolling and sectionalizing the line to locate the fault.
2. Installation of Auto-reclosers
The Municipality procured 15 Auto-reclosers in the last financial year and 12 of these have been installed and commissioned. An Auto reclosers (ARC) is type of switchgear designed for use on overhead electricity distribution networks to detect and interrupt momentary faults. These have been installed strategically on T-Offs and other parts of the network that are performing poorly.
When momentary faults are detected, the ARC switches off that part of line and automatically close it back after a few seconds. If the fault is cleared supply is restored to that section, however if it is a permanent fault the ARC will open and lockout leaving only that part without supply. The advantages realized are that only a few clients are affected because the feeder does not trip at the substation and officials will patrol only that portion of the line as opposed to the whole feeder.
3. Construction of a new 33/11kV (Modderfontein) Substation
Pre-Engineering scope is currently underway to construct a new Substation which is located at the Load Centre for the rural network. At the moment, the rural network is fed from Kroondal Substation which is located further off the load centre causing under voltages due to extended line lengths. Once commissioned, the substation will be linked to the Waterkloof Hills Substation providing a contingency and strengthening the supply to the rural networks.
4. Construction of a new 11kV Bulk Line to Dinnie Estate
Construction of a new 11kV bulk line, which will be fed from Waterkloof Hills is currently underway with anticipated completion at the end of February 2021. Once commissioned, the network will be split reducing the load profile from Kroondal Substation with an improved quality of supply to all areas in the vicinity of the R24.
5. Replacement of cracked Insulators/ Tensioning of conductor
Cracked Insulators and sagging conductors have been identified as the most contributory factors for frequent power outages on the rural networks. Orders have been placed for the procurement of 11kV Insulators and once delivered, the Municipality will roll out a replacement program from Mid-February 2021 for all porcelain insulators with rubber, long rod insulators which will run simultaneously with the tensioning of conductors.
6. Vegetation Control
The vegetation growth underneath the 11kV rural lines is the most contributory factor for the power outages on the rural network. Trees touching the lines cause consistent power outages whenever there’s inclement weather. A tree pruning program was rolled out by the Municipality in 2019 and subsequently stopped upon the expiry of the contract with contracted services. A lot of challenges (with particular reference to plot/farm dwellers) were encountered in the execution of the program which hindered the successful completion of the exercise.
The following were some of the challenges:
Access to the lines where they run in private property, culminating in those sections not being pruned.
Resistance by some community members on cutting down certain species of trees.
Communities deliberately planting trees under the lines.