The link box in this case is a universally used sealed junction box placed either in manholes or cabinets and that accommodates surge protectors as well as a point to cross-bond the sheaths. While a range of configurations is used to reduce losses in cable systems, (including cross-bonding of the sheaths and transposing phase conductors) segmentation along with surge protection of the cable jacket is considered the most effective. MAPPEC – Materiales, Productos Poliméricos y Elementos de Construcción 2: Loss reduction in cable systems using segmentation and sheath voltage limiters. This can become a point of moisture ingress, which can lead to long term dielectric and failure issues. Otherwise, the voltage differential between sheath and earth can exceed the cable jacket’s withstand, leading to puncture. However, if segmentation is used to interrupt induced sheath current, measures must also be taken to limit voltage induced on the sheath during transient events. In the process it can also raise the temperature of the cable, which then becomes a limiting factor in the system’s overload capability.Ī common means to reduce such losses is to segment the cable sheath (as in Fig. Because cable is often installed with metallic sheaths, current is induced onto the sheath from the primary conductor and flows directly to earth, representing a 100% loss of energy. Growth in installation of underground cables has focused more attention on some of their potentially negative environmental effects. 1: Simple HV cable showing polymeric jacket that may require surge protection. Version 2.3.7 contains a couple of important improvements, not described here, that you will certainly enjoy.Fig. IMPORTANT NOTE FOR WINDOWS USERS: Please update your copy of iNMR. All you have to do is to save your numerical values in a suitable text format. In practice you can use iNMR to display not just NMR data, but any kind of numerical data. The number of different styles that are accepted by iNMR has now increased to four. It explains how you can import any kind of 1-D or 2-D table into iNMR via a textual file. Before the end of the week a new version of iNMR has been released.Ī page of our web site has been partially rewritten. A better proof of my theory is that no user had ever asked for it until this week. My impression is that Covariance is not so important in the NMR context. At first examination, all those pages were written by a handful of teams. The trivial trick is to transpose the matrix, if necessary, before selecting the command Process > Covariance.Ī Google search for "Covariance NMR" yields over 2000 results. If you start from a 13-C vertical axis, you will get two 13-C axes. If the starting vertical axis is a 1-H axis, after Covariance both axes will point to the 1-H nucleus. For this reason, the distinction between direct and indirect covariance is unnecessary. This notion is absent in NMR, where transpositions occur too frequently, either invoked by the processing engine or by the user (whenever you click Shift-T). This link leads to the pioneer of the method:įrom my point of view there is no difference between direct and indirect Covariance, because they start from the notion that a given axis belongs to a given dimension. Both are homo-correlation plots.Ī more detailed description is available here: The so-called Indirect Covariance creates a symmetric C-C matrix. The so-called Direct Covariance creates a symmetric H-H matrix. Starting from here you can apply two different kinds of Covariance. After normal processing, it has two different axes: a 1-H axis and a 13-C axes. An example is hsqc-tocy (a kind of hetero-correlation experiment). The result can look completely different from the starting spectrum, though the information contained is necessarily the same. This technique creates a symmetric square matrix, starting from any 2-D matrix. The new versions 5.3.7 (for Mac) and 2.3.7 (for Windows), both available since June 20, add Covariance NMR to the processing toolbox.
0 Comments
Leave a Reply. |