Protection gap

The protection of aluminum ships demands particular attention since electrical contact with steel and copper materials can seldom be avoided and a whole range of aluminum alloys are unsuitable for cathodic protection (see Section 2.4 and Fig. 2-11). Later protective measures must therefore be observed during the construction stage since even good coatings in combination with cathodic protection are frequently not adequate to protect gaps or openings. 

Note to paragraph (c)(1)(ii) See Appendix B to this subpart for information on how to calculate the maximum anticipated per-unit transient overvoltage, phase-to-ground, when the employer uses portable protective gaps to reduce maximum transient overvoltages. 

When the employer institutes control of maximum transient overvoltage at the worksite by installing portable protective gaps, the employer may calculate the minimum approach distance as follows ... 

Step 1. Select the appropriate withstand voltage for the protective gap based on system requirements and an acceptable probability of gap sparkover. ... 

Surge arrester application is beyond the scope of this appendix. However, if the employer installs the arrester near the work site, the application would be similar to the protective gaps discussed in paragraph IV.D of this appendix. 

Problem Employees are to perform work on a 500-kilovolt transmission line at sea level that is subject to transient overvoltages of 2.4 p.u. The maximum operating voltage of the line is 550 kilovolts. Determine the length of the protective gap that will provide the minimum practical safe approach distance. Also, determine what that minimum approach distance is. 

This value equals the withstand voltage of the protective gap. 

Step 2. Using test data for a particular protective gap, select a gap that has a critical sparkover voltage greater than or equal to ... 

For example, if a protective gap with a 1.22-m (4.0-foot) spacing tested to a critical sparkover voltage of 665 kilovolts (crest), select this gap spacing. 

Adjacent structures. The employer may install the protective gap on a structure adjacent to the worksite, as... 

How to use portable protective gaps to limit maximum transient overvoltages at the worksite and thereby reduce minimum approach distances, and... 

How to calculate minimum approach distance when employers use portable protective gaps. 

An example of these sediment transport patterns can be seen in Fig. 22.14, which consists of a bottom survey carried out in Lido di Dante (Ravenna, Italy). The coastal defence in this site is composed of three groynes, two detached zero freeboard LCBs with a protected gap in between, and two low-crested coimectors from the northern and southern groynes to the LCBs (Zyserman et Zanuttigh ). Deep crescent-shaped erosion areas at about 70 m from the two barrier roimdheads can be recognized, which have a maximum depth of 1.5 m, a length of 150 m, and a width of 50 m. A flame-shaped erosion hole, 1.0 m deep, 120 m long, 50 m wide, is present seaward of the central gap, due to the rip current concentration and intensity. Deposition occurs seaward the detached LCBs, due to wave breaking at the offshore LCB slope and to return currents from the roimdheads. 

As noted, much of the research and discussions on the displaced in urban areas focuses on the content of the policies itself and the presumed consequences for refugees and other people of concern. This work offers important critiques and draws attention to protection gaps, logical contradictions, and oversights. However, the tendency (p. 145) of existing scholarship to focus almost exclusively on the displaced and policies directfy framed in terms of displacement... 

BADIL (2005) Closing Protection Gaps Handbook on Protection of Palestinian Refugees in States Signatories to the 1951 Refugee Convention. Bethlehem BADIL Resource Center. 

Keywords protection, refugees, legal instruments, international cooperation. United Nations High Commissioner for Refugees, protection gaps, displacement... 

Ultimately, the feasibility of suggestions to fill protection gaps will depend on the commitment of states. However, it is clear that the effectiveness of measures to address protection gaps would be limited if conceived in only abstract, conceptual, and theoretical terms. If such measures are not tied to specific, concrete problems or situations, which elicit a measure of political interest and a willingness to cooperate, their feasibility would be doubtful. It is likely that states would be reluctant to commit themselves to models or mechanisms in the abstract. If at all, these would then remain vague, and thus add little as a tool or to increase predictability of responses. 

UNHCR (2010) High Commissioner s Closing Remarks, Dialogue on Protection Challenges Protection Gaps and Responses. Geneva Palais des Nations, 9 December. 

Whilst protection gaps do exist in relation to internally displaced persons and stateless people, this chapter focuses on cross-border displacement... 

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