The electric power system is a highly complex and dynamic entity. One malfunction or a carelessly set relay can jeopardize the entire grid. Power system protection as a subject offers all the elements of intrigue, drama, and suspense while handling fault conditions in real life. The book reflects many years of experience of the authors in teaching this subject matter to undergraduate electrical engineering students.
The first form of AAS was developed by the Australian chemist named Sir Alan Walsh in the 1950s. The most powerful instrument for quantitative determination of trace elements in liquid (Bunsen & Kirchhoff, 1950). This method provides a total metal content of the sample and is independent of its molecular form. It works on the principle that free atoms generated in an atomizer absorbed radiation at a specific frequency. After NAA, a very sensitive and convenient technique for elemental detection of gunshot residue came. It can detect elements in nanograms and pictograms depending on the principle of where elements absorb the radiation of the same wavelength it emits when excited. First, the AAS-based detection of gunshot particles was reported in 1971. Based on the amount of element or metal constituents, AAS help to reveal the information whether a person fired or not. Results obtained using these techniques gave approximately a 90% case at success. It is a method which is very sensitive for detection of lead metal in GSR samples but gives less result in Ba and Sb amount. To determine Ba and Sb, only atomic absorption spectroscopy is not sufficient while flameless or electrochemical atomizer help to analyze these metals. Some researchers applied fluid nebulizer with flame furnace AAS to improve the detection of tin, in comparison with conventional flame AAS. When compared with conventional AAS, fluid nebulization was found to be more sensitive and with a less detection limit.
First given by Mikhail S. Tswett when he did his study on separation of plant pigments. HPLC is just the opposite of GC where the moving phase is liquid and the stationary phase is solid. Here, the liquid is passed through a column filled with solid particles (A Chromatographic and Electrophoretic Methods/A High-Performance Liquid Chromatography, n.d.). The liquid carries the sample pass through the column, different components retarded at different times. In HPLC, room temperature is sufficient to carry out the experiment. Amperometry and coulometric detection with mercury and carbon electrodes respectively to analyze NG and DPA using size exclusion chromatography for nitrocellulose were done by Lloyd (Basu & Ferris, 1980). Speers et al. (Speers et al., 1994) evaluated the use of HPLC-PMDE and GCMS for the analysis of organic propellant powder. He combined the technology with SEM/Edx to analyze inorganic residues. Dahl et al. (Dahl et al., 1985) reported the use of HPLC-EC for swabbed stabilizer detection. These stabilizers serve as an identification means of gunshot residue. Some scientists combine both high-performance liquid chromatography with pendant mercury drop electrode detector (HPLC-PMDE) and GC-TEA in combination to get better results, as these combinations lead to a strong or powerful result with more validity. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed by Wu et al. (Wu et al., 2001) for detecting methyl centralite used in GSR as a stabilizer. Even they searched that 25% of MC remain in a sample after 2 h. 2b1af7f3a8