Getting Technical
CHARLES NICOLSON
Charles Nicolson has a physics and chemistry degree from Natal University which he subsequently put to
good use by applying speciality chemicals in mining and industrial processes where water is a major factor.
This created an enduring interest in water technology, a passion that expanded to the HVAC industry
in 1984 when he joined BHT Water Treatment. Since then, water technology in HVAC water circuits has
continued to be an abiding interest.
REDUCING THE IMPACT OF LOAD SHEDDING
– A PERSONAL EXPERIENCE
By Charles Nicolson
Even though it is a perfect evening at just after six o`clock under a
deep blue autumn sky in Johannesburg I catch myself, once again,
murmuring an audible "Thank You" as the lights come on.
ot that I need any lights just yet, but it is reassuring to hear
the soft hum of the refrigerator ensuring that frozen food as
well as other cooled liquids such as milk will not require earlier-
than-usual replacement. However, I wonder who am I actually
saying "Thank you" to?
The person or people who moved the switches or pressed
the buttons so that electric power was restored to Block 2A and,
at the same time, removed power from another block in which
reactions from residents and others in the affected area would no
doubt be expressed more abruptly and in words far different than
my murmured "Thank You"? Or is disconnecting electrical supply
to an area and subsequently reconnecting several hours later now
actuated by pre-programmed computerised control systems?
Probably not, I thought, bearing in mind that even small electrical
grids fed from sub-stations contained various ranges of voltages,
amperages and other complexities requiring control as well as
safety considerations.
Time for tea.
A welcome return to normality; but as I switch the kettle on
the power dies again. Hoping optimistically that some error in
the procedure for restoring the power had occurred and that
it would be rectified soon and remain on at least until the next
scheduled ‘load shedding’ arrived, I left everything ready for
brewing up the tea, including a check that the kettle was not
switched on. Why bother to check if a standard 2000W domestic
kettle is switched off? 2kW is a tiny, virtually negligible part of
the multi-megawatt demands of power by the total of over 50
suburbs in Block 2A, even during the early pre-morning period
of lowest power demand.
The reason is partly habit because electricity usage on the
property where I live has far outgrown the design capacity of the
www.hvacronline.co.za
N
Figure 1: A typical
portable 750kW
220/230 VAC
generator.
original installation put in about 70 years ago. For example, the
original 2kW hot water geyser has been supplemented by two
more 3kW units and there are now three refrigerators so too
many additional appliances coming on simultaneously causes
trip-outs on the incoming supply panel which is awkward to
get to for re-setting the trips. The other part of the reason is a
practically insignificant but personal recognition of the efforts
by the many people involved in both Eskom and City Power who
are genuinely striving to improve both quantity and quality of
electrical power supplies.
A couple of years ago I was asked by an old friend, who also
lives alone in a small rented garden cottage of similar size in a
neighbouring suburb, to calculate the minimum-sized generator
he would need, so that during load shedding durations of four to
five hours he would be able to use two ordinary electrical lights,
a 3kW electrical fan heater, a 900 watt electrical /microwave
oven, his 2kW kettle and his television set with decoder for DSTV.
This total capacity of about 6.5kW would need a generator
Continued on page 57
RACA Journal I May 2020
55