Condition monitoring Essay Example | Topics and Well Written Essays - 1500 words

Condition monitoring - Essay Example Common electrical components like transformers and power cables are tested for partial discharge as part of a quality assessment framework. In fact, detection of partial discharge is a common practice adopted by electrical manufacturers across the world since the 1980s. Testing for partial discharge is necessary to improve the quality and reliability of electrical systems, as it has been cited as one of the primary reasons for failure of electrical systems (Bengtsson, 2003). The presence of partial discharge indicates a partial damage to the insulation that can lead to speaking effects along the insulation surface. Thus, detecting partial discharge helps in the identification of flaws like cracks and voids where there is a maximum probability of electrical stresses that can lead to a breach of the insulation. The analysis of partial discharge can be carried out using several predictive tests that identify any degradation of the insulation before such a condition leads to the damage o f the system. Such testing can further be carried out in standard operating conditions and does not require any special arrangements. Zhiqiang, (2004) says that typical methods of detection include acoustic, electrical and chemical techniques that do not affect the insulation system. Besides, all these methods for detection can be undertaken at reasonable costs and thus find widespread acceptance in the industry. This paper discusses the acoustic method of partial discharge (PD) detection by describing the advantages and disadvantages of the technique. Further, data has been sourced from 6 different research papers that analyze the acoustic PD method from different perspectives. Discussions and inferences from these individual papers has been presented and compared wherever appropriate. Possible future trends for acoustic PD testing have also been discussed in brief. Acoustic detection of PD Blackburn (1998) says that the acoustic method for PD detection relies on the identification , processing and storage of the signal resulting from a partial discharge. The acoustic signal generated during a PD occurrence is detected and recorded by the acoustic PD testing arrangement. The technique is similar to the generation of thunder during a storm. The acoustic signal is generated when a current streamer develops within the void space. The material surrounding this volume becomes vaporized leading to an explosion that releases a detectable amount of mechanical energy. The released energy then travels along the electrical system’s volume as a pressure field. The acoustic PD detection technique is mostly used in gas-insulated substations as well as in High-voltage transformers. Detections systems that employ this method are also differentiated based on their construction, into internal and external acoustic PD systems. Internal PD systems consist of a sensor that is placed within the transformer tank to detect the magnitude of the pressure wave through the oil med ium. In contrast, external PD systems are based on sensors that are attached to the outside wall of the transformer tank to monitor the pressure wave. Amongst these two methods, the external PD systems are more widely used in the industry due to the ease of construction and operation (Darley, 2001). The main benefit of the acoustic PD detection method over other available techniques is that the information on the position of the PD can be retrieved instantly from the PD detection system through

The Founding of the Caliphate Essay Example | Topics and Well Written Essays - 1250 words

The Founding of the Caliphate - Essay Example People’s right like social security, family structure, rights of women and children were tremendously improved in his time but his sudden death in 632 created disarray in the society (Ahmad 246–248). He never specified anyone as his successor who will rule the Muslim ummah after his death. Soon after his death, a debate started over the selection of the next leader among two groups of the regions, Al-Tabari and Ibn Hisham, however, these debates were not reaching to any implications. Background One of the Helper groups of Muhammad was Banu Sa’ida. It was a Jewish tribes from Medina who helped the Muslims when the emigrated from Makah to Medina. They were also included as the allies of Muslims in the constitution of Medina. But soon after Muhammad’s death the group gathered and decided to take the authority of Medina. They said that their tribe has precedence in religion and merit in Islam that no Arab tribe had and now is the time to take the authority bac k. They said that Allah has conferred merit on them and they were the ones who fought more heavily than any other for the glorification of Islam and Muhammad against his enemies in the Holy wars (Edmund). They were acclaiming that it was through their swords that people came near to Muhammad and Islam and now after His (PBUH) death, it is only their right to keep the authority for them and not for anyone else. On the other side, many of them were also thinking that emigrants of Quraish, the first companions of Muhammad who came with him to Medina, would refuse their authority. This news reached to Umar, the companion of Prophet who approached to Abu bakr with this news. Abu-Bakr was preparing for the burial of Muhammad’s body (PBUH) at that time and was in a state of shock. But Umer insisted his presence outside. He informed him that Helpers have gathered in the porch of Banu Sa’ida and willing to confer the authority to Sa’d Ibn Ubada. Abu-bakr joined Umer with his companions and sat in a meeting with Banu Sa’ida to resolve the issue of authority. Umar ibn al- Khattab wished to make a speech there but Abu Bakr asked him to let him speak first and afterwards he speaks whatever he wants to. Speech of Abu Bakr To settle the situation at that time and to avoid any kind of chaos in the state, Abu-bakr made a historical speech. He started his speech by praising Allah and said that Allah sent Prophet Muhammad to His creatures to lighten up their hearts and to show them the right path of worshiping Allah and Allah alone. He said that they were living in darkness and worshipping various gods and considering them as intercessors for them with God, though they were only made of stones and carved wood. In such situation it was a tremendous thing for the Arabs to abandon the religion of their forefathers and accept Islam as the true religion. He said that it was the Allah’s blessing that Emigrants (people of Makah) were the first HE sele cted for His religion. Allah showed them the right path with the guidance of Prophet Muhammad and they soon recognized the truth that Allah is the only one worth worshiping. Emigrants were few in numbers in the beginning, their tribes were against them but they never got afraid and stand stiff against all the enemies of Islam. Abu Bakr said that Emigrants are Prophet’s friends and among his clan and he believes that they are the best entitled of all the men to