Protection of electronic equipment from elevated potential of the neutral wire in IT-earthing system

Thumbnail Image
Journal Title
Journal ISSN
Volume Title
University of Dar es Salaam
This research addressed the development of a system to protect electronic equipment from the effects of elevated neutral to earth voltage (NEV) in TT (Terre to Terre) earthing system. The TT- earthing system is one type of earthing which is simple to use and of low cost used in low voltage power distribution systems for personnel and property protection. In TT-earthing system the neutral wire earthed at the distribution transformer tends to be elevated at higher potential (voltage) above zero mainly due to unbalanced loading and harmonics in 3-phase, 4-wire supply system. This tends to raise the potential of common ground for electronic equipment above zero, causing improper functioning, life time reduction and sometimes destruction of electronic equipment. By Measuring the NEVs and consultation with technical personnel at sampled places in Tanzania, it has been found that in these places the problem of elevated NEV is serious. The measured NEVs in these places were between 4V – 103V which is unsafe for proper operation of electronic equipment. In this research works compact, light weighted, low cost, an effective and simple system using simple, few and common electronic circuits/ components has been developed. The system is about 480cm3 in size, weighs about 0.2kg, costs not more than Tshs 100,000/= and able to reduce the elevated NEV to nearly 0.9V. The system is more advantageous than its counterpart’s e.g. the shielded isolation transformer which is about 4744 cm3 in size, weighs about 6.4 kg and cost more than Tshs 100,000/=.The developed system will reduce this problem and thereby protect many electronic equipment.
Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark ( THS EAF TH9445.E46M3254)
Electronic apparatus and appliances, Fires and fire prevention
Mbilinyi, J. G. (2016) Protection of electronic equipment from elevated potential of the neutral wire in IT-earthing system, Doctoral dissertation, University of Dar es Salaam, Dar es Salaam