Ti Grounding System

Topics: Earthing system, Electricity distribution, Ground Pages: 5 (1937 words) Published: August 3, 2012
Smart solutions overview of street light system in TI grounding system There are many of electrical equipment which can be accessed by the public; however, some of them cannot be physically controlled by the operator. One of them is street light system which needs to be protected in order to prevent shock hazards under the fault conditions. Generally, street lighting systems are distributed in a large area including urban and sub urban. If fault happens, the metal case of these systems might raise a potential hazard which could lead to expose people to shock hazards. The typical protections are bonding and grounding to reduce the risk to an acceptable level. This technical literature review will be based on an IEEE paper titled “Electrical Safety of Street Light Systems” by G. Parise, L. Martirano, and M. Mitolo (2011) [1]. This will be demonstrated firstly by explaining the terms and content involved, secondly by discussing the work in the paper and finally presenting the contribution of the paper and the key learning point. In this article, the authors organize the content in eight sections. In the first five sections, the authors present the street lightning system in general, the protections used, and variation of street lighting system according to the grounding systems applied. In section six, the authors describe an example in US. The main content is in section seven where the authors explain about proposed solutions which mainly regarding to improve TI system. Finally, the authors put the conclusion and suggesting the future area of research. Street lighting systems are a common case of distributed low-voltage load in wide areas. It usually protected by the same devices. Electrical utilities are commonly owned and operate this system. IEC 60364 [2] has set the standard of Class II to be used in street lighting systems. The purpose is to protect the systems against indirect contact. The term of Class II in here include the wiring systems, the light fixtures, etc. which have double reinforced insulation. Under normal condition and proper maintenance system, the risk of insulation break down is significantly low. However, the authors here mention the major issue that it might fail during its life cycle. It could be mainly caused by improper maintenance due to the wide area covered and also can be a result from extreme conditions such as vehicle impacts or animal intrusion into poles. Therefore the authors propose possible alternatives for the protections systems beside that are already mentioned in IEC standards. The authors suggest increasing the safety level of Class II metal poles by applying a special circuitry and bonding connections. The purpose is for providing continuous information about the double insulation status. Section one until five are actually already covered by the authors in their previous paper “Grounding of Distributed Low-Voltage Loads: the Street Lighting Systems” published by IEEE in 2010 [3]. It includes protection against indirect contact and types of grounding in section two. This part is mainly explain protections in low voltage system related with grounding systems which can be carried out from a common earthing electrode to source and load; known as TN system; or through independent grounding systems; known as TT system. The authors’ explanations will mainly on improving TI system which is not formally defined in IEC standard. In TI systems, there is direct connection of source neutral to earth and exposed conductive parts (ECP) are not connected to the ground. All grounding systems are based on reference [4]. This includes also the TN-S; with separated neutral wire and protective conductors (PE); and TN-C-S systems; with combination of separated and a combined neutral wire and PE as a single conductor known as PEN. The grounding systems mentioned are based on outdoor installations as mentioned in reference [5] In street lighting in TT system environment, the authors conclude that...
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