Due to the current load shedding and Eskom’s endless problems, a lot of people have turned to generator and automatic change over panels to handle a quick and seemingly easy transition from the grid to backup solutions.

Talking electricity with Andrew Luke Dapshis

Many of the latest automatic change over panels have numerous measuring devices working through a controller that constantly monitors your mains supply along with your generator’s load in order to best protect your electrical infrastructure. It works through a dual set of interlocked contactors to change from municipal to generator supply. So, in many of the older areas where the municipal electricals systems haven’t been upgraded for 20+ years, at various times to handle the massive demand on these systems and the volt drop that inevitably happens, the municipal supply increases their voltage in order to handle the prime time requirements. So the three phase voltage picks up from 380-402 V to 450 V and the controller on the automatic change over panel picks up this increase in voltage and decides it is best to start and run the generator and disconnect from the mains in order to best protect whatever machinery is being run. Many times this transition happens within a split second, depending of course on what which is bought. Many of the newer automatic change over panels can also be fitted with cloud devices, working through a 3G sim card to allow real time access to your system via your cell phone and send you messages every time your generators starts or has a fault.

But now we sit with an issue in many cases with older systems utilising new technology; people have no indication that anything is wrong with their systems as no one sits motoring their drawn voltage or current on a by minute basis.

So Mary Mango buys a rundown building in the old part of town and turns it into a success, so she opts for a generator due to constant load shedding. Knowing nothing about electricity, the salesman sells her a 20 kW to supply her shop with a great standby option and to do this seemingly she buys an automatic change over panel. Now prime time comes and Mary hears her generator starting up and her fluorescent lights flicker, but across the road, Larry’s Laundromat, which doesn’t have a generator, is still running off grid power. Mary thinks that she has bought a dud setup that has gone bonkers, but seven minutes later she hears her generator stop, the fluorescent’s flicker and she is back on municipal supply. This happens a few times and Mary gets upset and calls the generator company, claiming the system is faulty and is costing her a lot of diesel.

A technician is despatched and is greeted with a host of mains voltage drop/overload alarms on the automatic change over panel controller, and must now explain in easy-to-understand terms why it is constantly switching on the generator. Systems like these can, of course, be bypassed, but then you are eliminating a safety device set to protect your system and, in many cases, once you have done that there is a chance you could void your warranty. Always ensure, no matter where you are, that if you are going to spend a large amount of capital on a standby solution that you organise a data logging electrician to do a test on your system to ensure you know, and are advised according, to your load and the municipal supply.

Another element to always check is phase rotation, as many of the older municipal supplies are still anti clockwise and most, if not all, new generators are clockwise. This will of course cause a change in motor direction if you don’t swop two phases around on your generator’s isolator.

There are many different panels and backup solutions out there; ensure you choose one that can supply your current load requirements at its peak and, if necessary, ensure a dummy load is present when the current drawn is less than 50% of the generator’s kW rating. There is much load shedding and electrical challenges ahead in our great country, so ensure you do your research before spending thousands and gathering further frustration when it doesn’t function correctly.

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Gregg Cocking
Email: sparks@crown.co.za
Phone: +27 11 622-4770
Fax: +27 11 615-6108

Advertising Manager
Carin Hannay
Email: carinh@crown.co.za
Phone: +27 11 622-4770
Fax: +27 11 615-6108

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Crown Publications, one of South Africa’s largest business-to-business publishing houses, came into existence in 1986. Since then, the company has grown from producing a single magazine, Electricity SA (renamed Electricity+Control), to publishing six monthly magazines, three quarterlies, and a number of engineering handbooks.