Consider an industrial plant supplied by a power line or power lines a few tens of kilometres long built only for the purpose of supplying your plant and that your plant draws about 20 MW.

Under this condition, it would be normal to have, at your end of the line, some devices, known as ‘capacitors’, which keep the voltage at your end stable. Capacitors have the characteristic that, once you switch them off, you have to wait for five minutes to turn them on again.

So, imagine that all is going well and your enterprise is humming along and then . . . there is an Eskom dip. Probably most of your load will remain connected but the capacitors will not. If this happens, the voltage at your end will start falling. As it falls, in less than five minutes, your remaining connected load will draw more amps, which will result in the voltage falling, causing your load to draw more amps. This will ultimately lead to a lot of your equipment tripping and it is a big hassle to try to get it all up and running again.

Oh . . . I hope I have not run through this all too quickly. Okay? Now about six years ago, I was at a meeting of some engineers and their consultants. The engineers had a large plant which had a single big electrical load at the end of longish power lines, with switched capacitors at the consumer’s end. The customer wanted to increase the load drawn through the existing lines. I examined the idea and wrote a report. In the report I said, no, bad idea – if you have an Eskom dip, you will lose your whole plant; it will trip.

I thought I was being very smart to tell them this. I was probably the only engineer who had actually seen this happen. In 1988, I had seen the voltage at Port Elizabeth’s Eskom Grassridge substation ‘slide’ from 220 kV to 204 kV for no apparent reason. So we (my Eskom controller) disconnected Port Elizabeth to save all the Eastern Cape consumers in the southern regions from a power outage while we figured out what the heck had happened.

But back to the engineers and their consultants. Far from being pleased that I had pointed out a fatal flaw in their electrical expansion plans, they were most unpleasant. They (one engineer and the senior consultant) pointed out that they knew their electrical system far better than I did. The engineer said, with withering scorn, that they “had timers fitted to restart loads”, so the matter would never arise. They told the people who employed me (some civil engineers) that I had wasted their time and money, that I had some ‘airy fairy theory’, which was gross rubbish, and that they really had expected some useful input to their idea of increasing the load on their existing lines. I refused to support the loading of their existing power lines and wrote my report accordingly. The civil engineers never employed me again. Fortunately (for reasons I do not know), the project did not proceed.

I was 100% right and they 100% wrong. But they would not listen to my reason. I was reminded of this when I recently spoke to an engineer who told me of the very detailed engineering that went into the design of the grid connection of a photovoltaic power plant. Wow, he said, very complicated, the consultants cost a fortune.

I told him I could not see why. Basically the whole plant (10 MW in size) was just a couple of transformers supplied by some invertors feeding into a grid. No more complex than the 132 kV power supply to a railway traction line.

Boy, did he say how wrong I was! Clearly, he said, it was more complicated than I knew. The consultants cost a fortune! Well, I figured. Perhaps they did. But probably they needed the money to go back to school and reinvent the wheel. These days it happens a lot. The stuff learned time back has been forgotten. Electrical engineers know not that they know not. A ‘back to basics’ is needed. But is it possible?