����������������� Presented�By Presented�By- - Presented�By Presented�By - - ��������������� ����� ������������� ������������������������
Objective of the session � Create an awareness about importance of electrical safety in our day today activities , in industrial applications and in our day today activities , in industrial applications and in construction Industries .
Topics Coverd � Competence � Electrical Hazard � Earthing System � Documentation � Guidelines for Maintenance & Testing � Guidelines for Maintenance & Testing � Portable Equipment � Using PPE � Cable selection Criterion and precautions � Statutory Norms
Competence Competence
Purpose of competence � Deployment of right workmen for a particular job to enhance productivity complying safety. � Development of supervisors and workmen skill by various means . � Development of supervisors and workmen skill by various means . � Development of a robust process which enhances the skill set of the people . � Inculcate a culture for safety.
Competence Development Competence Technical Statuatory On Field Training Training by OEM Class Room Training Workmen Electrical Licence for Supervisory Licence Development through Workmen CSR activities
Classification of Licence for supervision and execution � LT licence up to 415 V � H.T Licence up to 33 KV � EHT licence beyond 33 KV � � Licence for HT jointer Licence for HT jointer � Licence From Director General of Mines & Safety Licence can be obtained � At state level � At national level
ElectricalHazard
MINIMUM SAFE CLEARANCE VALUES ���������������������� ������������� ��� ����������������� ������ �� ! "������ #$�%%��� �� & "%%��� #$������ ���' "����� #$�((��� ��! "((��� #$������ (�)) "����� #$�%(���� (�'( "%(���� #$���)��� '� ! "��)��� #$�'))��� �'*
Shock Protection Measures � Isolation � Current limitation � Low voltage � Double insulation � Earthing � Earthing � Over Current Protection Devices � Residual/Leakage Current Protection Devices 15
Isolation Transformer � Power can be tapped from isolation transformer � Avoids shock between earth and phase ������������ ����������� 16
Low Voltage � 24V hand lamps. � By earthing the mid point of a single phase transformer, the line to earth voltages are reduced to 115V while the full supply(230) is available to the apparatus. ������������� ���� ����������� ���� 17
Overcurrent protection devices Relays are the devices which sense the abnormal conditions from the power system and take trip decisions. ��� �� ������ ����� ����� � �� �� ����� ������������� ������� �������
RCCB WORKING PRINCIPLE ������������ ����� ! " #�! $ %�������� ����� ! " &�! $ �! " #�! $ '�! � � � (��))������� ����� ! � &�*+��, �+,�-��.� � � � � � � � � ��/��01�1.��� �,//�.�� �/1.23�/��/
Application of RCCB � Domestic & Industrial Lighting � Welding Machine � Refrigerator � Hand Tools
ELR WORKING PRINCIPLE � Normal E/F protection = Ir+ Iy+ Ib+ In=0. � During E/F , the residual current flows through neutral and in-built E/F release in CB operates .
Earthing Earthing 23
Purpose of earthing � Prevention of electrical shock. � Allowing passage to electrical fault current through least resistive path. � Sensitive Earth fault protection � Safety of the electrical system and equipment's.
Industrial Guidelines for earthling � The combined Electrical earthing value of electrical system to be less than 1 Ohm � Electronic earthing for PLC /DCS should be different from electrical earthing � � The value of the electronic earthing should be less than 1 ohm The value of the electronic earthing should be less than 1 ohm � Neutral of transformers should be separately earthed and should be able to isolated. � For residential applications the voltage between neutral and earthing not to exceed 5V. � All the equipment's to be earthed at two points
Methods of earthing � Deep bore earthing for soils having more resistivity � Use of good earth � Use of chemical earthing in rocky soils. � Earthing grid formation by MS rod or G.I flats
Sub-station Grounding Step Potential Step potential is the step voltage between the feet of a person standing near an energized grounded object. near an energized grounded object. Touch Potential Touch potential is the touch voltage between the energized object and the feet of a person in contact with the object. It is equal to the difference in voltage between the object and a point some distance away.
How to limit step and touch potential � Providing low resistance path to ground � Proper insulation between body and ground- By providing resistive surface layers � Proper design and installation of earthing conductors � Proper design and installation of earthing conductors � Use of current limiting reactors � Use of highly insulated shoes
Typical Earthing Scheme for Construction Power Facilities ������� ��������������� ��������������� ���������������� ������� ������� �������������������� �������������������� ������������������ ���������������� ����� �� ���������� ���������� �������������������� ���� �������������� ��� ���������� ���������� �������������������������� �����������������������������������
Documentation
Purpose/Importance of documentation � Adopt a systematic approach by following a robust safety systems during maintenance /operation. � Leads towards zero accident . � Minimises disruption in work � Boost up confidence of the working professionals . � Statutory Compliance – OHSAS 18001
Documents � Release work permit routed through concerned departments � Strictly adhere to the Lock Out Tag Out (LOTO) concept � Raising and mitigation of NCR ( non-compliance report) on regular basis � On line monitoring of NCR’s � Compliance of Check list prior to installation and safe energisation .
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