CONCERNED (affected) Engineer of Nimrod Park writes:
Permit me, as an electrical engineer with some 40 years experience in power distribution network design, construction and maintenance in the service of a large parastatal, to comment on the recent three-day power failure affecting areas of Kempton Park.
Power distribution networks are designed and installed to include surveillance protection systems to “trip out” feeding circuit breakers within milliseconds of the occurrence of a fault in a cable, transformer or other circuit breaker or switchboard, thereby quickly isolating the faulty item/s and limiting any physical damage which might result.
In networks with protection systems operating correctly, it is extremely unusual to have a “whole transformer” as well as circuit breaker panels burn out completely as that faulty equipment would normally have been protected. The “Bonaero Park feeder cables”, having developed a fault, should have resulted in upstream or ring feed circuit breaker/s operating and isolating the cable/s.
In properly designed, maintained and operated “ring main” systems, cable faults should be isolated without consumers even being aware of the fault.
So, while the metro spokesman’s assurance that “all our substations are up to date in terms of their maintenance schedules” should be comforting to ratepaying consumers, the hard evidence flies in the face of such a statement – at least in respect of the all-important protection systems which should be routinely tested and calibrated on a regular basis with any defects being attended to with the utmost urgency.
These comments are prompted by the recent spate of major damage to substations and equipment throughout the country and which are too easily explained away and accepted by the lay person as “cable faults” or “cable thefts” and other lame excuses. It is my considered contention that the “fault” more likely lies with management, training of staff and lack of attention given by power network operators to the vital protection systems so crucial to the economic operation of their extremely capital intensive equipment entrusted to their care by the taxpayers of this country.
Now obviously, I don’t expect a spokesman or a council electrical engineer to own up to the systemic problems I have raised, especially with their political master breathing over their shoulder, but I do wish to inform the public that the explanations emanating from the spin doctors are not always to be taken at face value.
On the positive side, EMM can be commended for holding spare stock of transformers, cables and MV switchgear otherwise the duration of the power outage would have been a lot worse.
