THE DISTRIBUTION POWER LINE DESIGN ENGINEER WHO GOT STUNG BY WASPS

Today I had the privilege to design some electric power delivery systems to supply Northern Region Water Board (NRWB) under their Karonga Town Water Supply Project, funded by The Department for International Development (DFID). I therefore visited their sites at Mlare, Balyenge (Mwenilondo), Bwiba, Nyanja Hills and Karonga Water Treatment Plant.

While at Mwenilondo, I was in the bush capturing geo-spatial data using a mobile mapper. Unfortunately I encountered some overzealous wasps and received multiple stings on my neck, just behind the left ear. I had to endure the pain without rubbing the affected area, as doing the same was multiplying it further a thousand fold. When I came out to the open where the two colleagues from NRWB were waiting, I was advised to apply some Colgate paste to ease the pain. I reluctantly obliged and played along. Fortunately my field kit had some toiletries as I was yet to check-in at my place of lodging.

One of the places had a power requirement of 1,322KW, which translates to 1,652.5KVA at the applicants power factor of 0.8 in-line with their Consultants (Note that our country's recommended p.f. is 0.85. Currently, the site is supplied by a 500KVA, 11/0.4KV, ONAN, Dyn11, Ground Mounted (GM) Transformer, which is fed by a 70sq.mm 3 core Cross-linked polyethylene (XLPE) copper cable on the primary side and a 300sq.mm single core copper armoured cable on the secondary side. According to our work procedures, this capacity requirement has to be referred to our System Planning counterparts to carry out load flow simulations of the whole distribution feeder for such a load. However, in order to deliver the requested power and to be in tandem with the transformer capacity standardisation of the employer, the probable transformer choice is 2,000KVA, 11/0.4KV  GM Transformer. This choice gives us 104.97A primary and 2,886.75A secondary currents respectively. This may eventually culminate into issues of cable sizing and market availability. Another choice, therefore, would be to split the loading onto two sets of 1,000KVA each.

ALIGNING RURAL ENERGY ACCESS TO TECHNICAL REQUIREMENTS

 

Power utility companies are under the  obligation to extend their distribution networks in order to meet energy access rate needs. To this effect, a distribution business unit, in most instances, would have a dedicated Section for this function. In the case of Electricity Supply Corporation of Malawi (ESCOM), this falls under the Distribution Planning and Development Section. 

This Section usually handles asset extension projects that may either be initiated and funded by the company itself, or indeed those requested by external customers. Basically, engineers in this Section are the first team on the ground. In the case of a customer request project, they are the decion makers whether a customer can be connected to the utility grid or not. They carry out several assessments ranging from a possible route that a power line will take, free from land rights obligation. Then they ascertain whether the system parameters are conducive to meet the power (or load) requirements of the customer. These may include transformer capacity availability, voltage levels etcetera. Then they proceed to design the system to meet all technical requirements that would enable delivery of quality supply to the consumer. Over and above technical data, they also capture geospatial data of the proposed network as well as Service Point. These are required for the team that would evenually construct the system, as well as billing requirements.

However, designing a power system for a rural set-up requires more than just technical system design. Often times in rural settings, especially those in sub-saharan Africa, what is required to deliver power to a consumer does not equate the ultimate economic returns on investment. This eventually culminates into a deeper area of concern popularly known as 'productive use of energy'. Going forward, most governments have to make a tough decision between increasing energy access to their citizens against economical benefits. This eventually becomes a tough debate between liberilising and privatizing power industries against having a monopolistic, and often inefficient systems of parastatals.