Posted By: Madhu Bafna

June 18, 2016
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Overview

Temporary installation during construction & repairs work: Majority of the fatal electrical accidents occur in generating stations due to 230 Volts electric supply lines, which are laid temporarily for lighting/ power during construction period. The lives lost are of construction labors. During the inquiry, it is seen that the attitude of the owner of line and the principle owner i.e. power station persons is very casual. Everyone stands away from the responsibility & measures the life in the monitory compensation. This is incorrect, and against the ethics of electrical engineering. It is accepted that the temporary installation is necessary, but there are means to do it very safely. The rules provides the obligation on the principal employer or the power station in-charge to see that all such works are done in utmost safe manner, and are maintained also. Both comment the breach of Indian Electricity Rules. The person from power station cannot escape the charge of willful negligence leading to the accidents. An officer must put an effort to that direction, so as to prove that he has exerted sufficiently and reasonably, but the situation was beyond the control due to natural forces. Use of E.L.C.B. and honor of provisions of Indian Electricity Rules would definitely stop the accidents in future. Fire in cable galleries: In Thermal Power stations, the Cable Galleries attract the Coal dust & any Arcing i.e. Earth Fault/Puncture may lead to Explosion. Instance have occurred, where such explosion leads to loss of millions of rupees and cumulative loss due to withdrawal of Generators from Grid. During Inspection, I have pointed out that the Cable installation is not properly looked. There may be another reason in practice. However, as a Executive, we have to adopt the modern & superior methods by which the Installation can be maintained in very much safe manner. Following are the deficiencies found in installation. 1) Accumulation of Coal dust in Cable racks. 2) Improper ventilation. 3) Inadequate lighting & Access for routine periodical inspection. 4) Seepage water in Cable Trenches. 5) Heating of particular cable runs due to loose connections/overloading/ sparking at Armoring. 6) Improper / inefficient Earth Connection to Armor. Damage to breakers & transformers: Many cases of accident are reported due to damage to H.V. / E.H.V. Breakers & Transformers. In most of the cases, there are internal faults, which occur instantly by weakening of di-electric parameters of the equipments. The periodical record of tests are not compared, and if compared the tolerance of the Officer may be due to threat of running down the plant, aggravates the situation, and becomes the cause of the accident. Taking Tests and comparing with the standards is the real missionary job, which is to be done with open mind and zeal, the study of International Standard. It is also seen that the manufacturing companies many times de-rate the Insulation Standard for the major Government Organizations for the reasons best known to all that how the same equipment, when supplied to private industries hold very high insulation qualities & values. Avoiding inter-locks & wrong operation of equipments: Recently, the accidents were reported in Power Station Yard due to operation of isolators on Load. It is prescribed by law that the isolators be Electrically inter-locked with breakers in such a way that it is operated only on no-load. Sub-station incharge has willfully breached this provision & caused an accident. Proper training to the operating persons should be given, so as to avoid the misconcept. Deteriorated earth mat: In the Generating Station or Sub-station Earth Mat is designed with a definite fault level, where more parallel connections, from various sources are brought. Naturally the Fault current level, which is adopted at the initial level becomes inadequate to take care of all faults. In this way, the general damage is caused due to high ground potential rise. Sometimes the protection cables are damaged due to excessive stress on insulation and sparking occurs at the armored end at the end boxes thus destroying the control. At times, this has compelled to shut down the Generating Station. For the human Safety of Operators in yard, the top surface, which is of Road metal, has to be necessarily dry to increase the foot resistance of human body. The switchyard, if full of Seepage Water, may deteriorate the grid and endanger the life of human being. Necessary effective storm water drain at 60 cm below the Ground level should be done to avoid danger to human life and property. Mental loading of maintenance officers: It is seen that many of the Technical Officers are loaded beyond the tolerable limit, and they do not get sufficient time to analyse the situation, read the data & compare with the standard to make the effective maintenance periodically. The Analysis of Faults should be computerised, and centrally published, so as to make it available for staff of all Generating Stations.

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