Safety and Security-1.pptx

Safety and Security-1.pptx

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  SAFETY AND SECURITY 1
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  PHYSIOLOGICAL EFFECT OF THE ELECTRICITY PROTECTIONOF PEOPLE 02/06/2023 TOT-M02-LE-000-MT-0001-ver1 2
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  02/06/2023 TOT-M02-LE-000-MT-0001-ver1 3 Definitions Internal impedance ofthe human body (Zi): Impedance between two electrodes in contact with two parts of the human body, after removing the skin from under the electrodes. Impedance of the skin (Zp): Impedance between an electrode on the skin and the conductive tissues underneath. Total impedance of the human body (ZT): Vectorial sum of the internal impedance and the impedances of the skin. Initial resistance of the human body (Ri): Resistance limiting the peak value of the current at the moment when the touch voltage occurs.
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  02/06/2023 TOT-M02-LE-000-MT-0001-ver1 4 Definitions Threshold of perception:The minimum value of current which causes any sensation for the person through which it is flowing. Threshold of let-go: The maximum value of current at which a person holding electrodes can let go of the electrodes. Threshold of ventricular fibrillation: The minimum value of current which causes ventricular fibrillation.
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  02/06/2023 TOT-M02-LE-000-MT-0001-ver1 5 Main causes are: •Operating mode inappropriate or dangerous (31%), • Lack of awareness of risks (30%), • Incomplete application procedures (15%), • Inadequate training (12%), • The state of the material (12%), • Soil conditions (11%)Type de contact In average, 75 % of the Electric shock is from indirect contact, 20 % from direct contact. Statistic shows that: • 1/3 of lesions are in multiple places. • Eyes, arms, hands are the most affected • 60% of lesions are burns, • 6 % of lesions are internal. Main causes of Electric shock
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  02/06/2023 TOT-M02-LE-000-MT-0001-ver1 6 Seriousness factors The levelof injuries caused by the electric current is due to a combination of several factors: • The intensity of the current flowing through the human body, • source of electrical energy (voltage, power) and the environment (insulating or highly conductive) • The duration of current flow through the human body, • The surface area of contact, • The particular susceptibility of the person subjected to the action of electric current. Main causes of Electric choc
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  02/06/2023 TOT-M02-LE-000-MT-0001-ver1 7 Value of theinitial resistance of the human body (Ri) Touch Voltage (V) Values for the total body impedance (Ω) that are not exceeded for a percentage of (population) 5% 50% 95% 25 1750 3250 6100 50 1450 2625 4375 75 1250 2200 3500 100 1200 1875 3200 220 1000 1350 2125 700 750 1100 1550 1000 700 1050 1500
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  02/06/2023 TOT-M02-LE-000-MT-0001-ver1 9 Current through thebody and effects In AC
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  02/06/2023 TOT-M02-LE-000-MT-0001-ver1 10
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  02/06/2023 TOT-M02-LE-000-MT-0001-ver1 11 In DC
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  02/06/2023 TOT-M02-LE-000-MT-0001-ver1 12 Direct – Indirectcontact Direct Contact Indirect Contact
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  VOLTAGE RANGE FROMIEC & RISKS 02/06/2023 TOT-M02-LE-000-MT-002-ver1 13 IEC voltage range AC DC Defining risk High voltage (supply system) > 1000 Vrms > 1500 V electrical arcing Low voltage (supply system) 50–1000 Vrms 120–1500 V Electrical shock Extra-low voltage (supply system) < 50 Vrms < 120 V Low risk
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  SAFETY PROCEDURE IN ELECTRICAL WORK (STANDARDSAND BEST PRACTICES) 02/06/2023 TOT-M02-LE-000-MT-002-ver1 14
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  PREVENT DIRECT CONTACTS •Remoteness 02/06/2023 TOT-M02-LE-000-MT-002-ver1 15
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  PREVENT DIRECT CONTACTS •Obstacles • Insulation 02/06/2023 TOT-M02-LE-000-MT-002-ver1 16
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  PREVENT INDIRECT CONTACT Byautomatic disconnection of supply • This principle consist in connected to the earth all metallic part of equipment and appliances. The disconnection can be done by MCB or RCCB depending on the earthing system. Without automatic disconnection of the supply • This can be done by three ways: • Class II equipment • Isolated circuits • Very low voltage 02/06/2023 TOT-M02-LE-000-MT-002-ver1 17
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  EQUIPMENT CLASSIFICATION Class 0 •These appliances have no protective-earth connection and feature only a single level of insulation and were intended for use in dry areas. Class 1 • These appliances must have their chassis connected to electrical earth . The earth connection is achieved with a 3-conductor mains cable. Class 2 • A Class II or double insulated electrical appliance is one which has been designed in such a way that it does not require a safety connection to electrical earth (ground). Class 3 • A Class III appliance is designed to be supplied from a separated/safety extra-low voltage (SELV) power source. 02/06/2023 TOT-M02-LE-000-MT-002-ver1 18
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  IP CODE (IEC.60529.2001) 02/06/2023 TOT-M02-LE-000-MT-002-ver1 19 TheIP Code, International Protection Marking (IEC 60529), classifies and rates the degree of protection provided against the intrusion (including body parts such as hands and fingers), dust, accidental contact, and water by mechanical casings and electrical enclosures. The standard aims to provide users more detailed information than vague marketing terms such as waterproof. The digits (characteristic numerals) indicate conformity with the conditions summarized in the tables below. Where there is no protection rating with regard to one of the criteria, the digit is replaced with the letter X.
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  02/06/2023 TOT-M02-LE-000-MT-002-ver1 20
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  IK CODE DEFINITION StandardIEC 62262 defines an IK code that characterises the aptitude of equipment to resist mechanical impacts on all sides. 02/06/2023 TOT-M02-LE-000-MT-002-ver1 21
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  OVERVOLTAGE CATEGORIES 02/06/2023 TOT-M02-LE-000-MT-002-ver1 22 Overvoltage categoriesclassification of live electric circuits is used in measurement and testing of installations and equipment, usually in the relation within a building (residential or industrial) There are four categories designated by a mark such as “CAT III, 150 V" or "CAT IV, 1000 V". • CAT I is applicable to instruments and equipment, which are not intended to be connected to the mains supply • CAT II defines circuits which are intended for direct connection into mains sockets or similar points. • CAT III is for circuits which can be connected to the mains installation of a building • CAT IV includes circuits which are connected directly to the source of power for a given building.
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  02/06/2023 TOT-M02-LE-000-MT-002-ver1 23
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  02/06/2023 TOT-M02-LE-000-MT-002-ver1 24 Rated Voltage IEC61010-1 2nd Edition CAT IV CAT III CAT II 150V 4,000V 2,500V 1,500V 300V 6,000V 4,000V 2,500V 600V 8,000V 6,000V 4,000V 1,000V 12,000V 8,000V 6,000V Resistance 2 ohms 2 ohms 12 ohms In addition to the label “CAT”, the maximum voltage must be marked. This voltage is the maximum voltage between live and ground of the circuit or the same overvoltage range.
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  SECURITY EQUIPMENT Personal protectiveequipment (PPE) • safety glasses • face shields • hard insulated hats • safety isolated shoes • insulating (rubber) gloves with leather protectors • insulating sleeves • flame-resistant (FR) clothing 02/06/2023 TOT-M02-LE-000-MT-002-ver1 25
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  Insulating Protective Equipment(IPE) • Insulating mat • Insulating tools • Insulating ladder • Insulating pole • Insulating stool • voltage detector • temporary-grounding and temporary-short-circuit set 02/06/2023 TOT-M02-LE-000-MT-002-ver1 26
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  02/06/2023 TOT-M02-LE-000-MT-002-ver1 27
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  Collective protective equipment •Protective screen • Poles, chains • Warning board and sign 02/06/2023 TOT-M02-LE-000-MT-002-ver1 28
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  MEASURING DEVICES The measuringdevice should: • Have an insulating case • Be Class II • Have an IP2X • Have the right measurement category. Accessories should have the same characteristics 02/06/2023 TOT-M02-LE-000-MT-002-ver1 29
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  02/06/2023 TOT-M02-LE-000-MT-002-ver1 30
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  Zone 1: Nonvicinity Zone 4: Vicinity area in LV (less than 30 cm from live parts). All equipment with IP < IP2X is considered as live part. Zone 2: Vicinity area in HV (up to red line) • 2 m (79 in) if U < 50 000 V (3 m -118 In – for aerial wire) • 3 m (118 in) if U < 250 000 V (5 m -197 In – for aerial wire) • 4 m (157 in) if U < 400 000 V (5 m -197 In – for aerial wire) • 5 m (197 in) if U < 750 000 V (5 m -197 In – for aerial wire) Zone 3 : This is the distance between the live part and the Minimum Distance Approach (MDA). In this area there a risk of electric arc. The MDA distance is 60 cm (24 in) up to 50 000 V. From 50 000 V the MDA is given by the following formula: MDA(m) = 0,005 x U(kV) + 0,5 02/06/2023 TOT-M02-LE-000-MT-002-ver1 31
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  THE PADLOCKING This theduty of the holder of BC / HC Electrical Authorization He does or supervises the padlocking He is responsible of the disconnection of the equipment from the power supply and the lock of the switch disconnector. He his establishing the acknowledgment of padlocking. (work permit delivred) 02/06/2023 TOT-M02-LE-000-MT-002-ver1 32
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  FIVE STEPS 02/06/2023 TOT-M02-LE-000-MT-002-ver1 33 Acknowledgment should besigned 2- Lock 1- Disconnect 3- Identify the equipment 4- Doing the Voltage checking and the earthing
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  FIRST STEP: DISCONNECTION Switchdisconnector Sockets Withdraw fuse Plug devices Control, protecting devices 02/06/2023 TOT-M02-LE-000-MT-002-ver1 34
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  SECOND STEP: EQUIPMENT LOCK Labeland lock device On LV equipment, Board with « Equipment lockout – Don not Manoeuvre » 02/06/2023 TOT-M02-LE-000-MT-002-ver1 35
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  THIRD STEP: IDENTIFICATION Identifythe place of the equipment Reading charts and circuit diagram Reading of labels and board Visual identification 02/06/2023 TOT-M02-LE-000-MT-002-ver1 36
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  FOURTH STEP: VOLTAGE CHECKING Thevoltage checking is carried out close to the working place The earthing and short circuiting should be done on both part of the circuit. 02/06/2023 TOT-M02-LE-000-MT-002-ver1 37
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  FIRTH STEP: MARKWORKING PLACE 02/06/2023 TOT-M02-LE-000-MT-002-ver1 38
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  PROTECTIVE DEVICES 02/06/2023 TOT-M02-LE_000_MT_0003-ver1 39
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  CIRCUIT BREAKER A circuitbreaker is composed • magnetic relay • thermal relay. It protect against overload and short circuit. Low-voltage (less than 1,000 VAC) types : • MCB (Miniature Circuit Breaker) — rated current not more than 100 A. • MCCB (Molded Case Circuit Breaker)—rated current up to 2,500 A, 02/06/2023 TOT-M02-LE_000_MT_0003-ver1 40
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  CIRCUIT BREAKER The characteristicsof low-voltage circuit breakers are given by international standards such as IEC 947. These circuit breakers are often installed in draw-out enclosures that allow removal and interchange without dismantling the switchgear. 02/06/2023 TOT-M02-LE_000_MT_0003-ver1 41
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  CIRCUIT BREAKER Inside ofa circuit breaker • The DIN rail-mounted thermal- magnetic miniature circuit breaker is the most common style. The design includes the following components: • 1-Actuator lever • 2-Actuator mechanism • 3-Contacts • 4-Terminals • 5-Bimetallic strip. • 6-Calibration screw • 7-Solenoid • 8-Arc divider/extinguisher 02/06/2023 TOT-M02-LE_000_MT_0003-ver1 42
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  CIRCUIT BREAKER Operating principle (MCB/MCCB) 02/06/2023 TOT-M02-LE_000_MT_0003-ver1 43
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  CURVES OF CIRCUITBREAKER (MCCB/MCB) 02/06/2023 TOT-M02-LE_000_MT_0003-ver1 44 Type Trip Protection Example of uses B 3.2 to 4,8 In Generators, people in TN and IT earthing system with long cables (no peak current) C 7 to 10 In Cables General uses D 10 to 14 In Circuit and load with High inrush current Motors Transformer
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  CURVES OF CIRCUITBREAKER (MCCB/MCB) 02/06/2023 TOT-M02-LE_000_MT_0003-ver1 45 Type Trip Protection Example of uses K 10 to 14 In Circuit and load with High inrush current Motors Transformer Auxiliary circuit Z 2.4 to 3.6 In Electronics Diodes Thyristors MA 12 In Motor (without thermal relay) Starters Motors
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  6.5.TRIPPING CURVES 02/06/2023 TOT-M02-LE_000_MT_0003-ver1 46
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  RCD (RESIDUAL CURRENT DEVICE)/ ELCB (EARTH LEAKAGE CIRCUIT BREAKER) The RCD / ELCB has been created to measure the current going through the lives and the neutral. If the sum of this current is not zero, this means that there is a leakage usually to the earth wire and the ground. 02/06/2023 TOT-M02-LE_000_MT_0003-ver1 47
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  RCD / ELCB 02/06/2023 TOT-M02-LE_000_MT_0003-ver1 48
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  TYPE OF RCCD Thedesign of RCD and ELCB are different depending of the circuit. • Industrial type circuit-breakers with integrated or adaptable RCD module • Household and similar miniature circuit-breakers with RCD • Residual current circuit-breakers and RCDs with separate toroid current transformer 02/06/2023 TOT-M02-LE_000_MT_0003-ver1 49
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  GROUNDING SYSTEMS (BASICS - STANDARDS) 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 50
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  EMERGENCE OF EARTHING SYSTEMS Todaythe 3 system earthing such as defined in IEC 60364 and French standard NF C 15-100, are: • Earthed neutral –TT (Terre-Terre) • Exposed-conductive parts connected to neutral –TN (Terre- Neutre) • Unearthed (or impedance-earthed) neutral –IT (Isolé-Terre) Those three earthing systems are created to ensure the protection of persons and property 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 51
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  52 The combination ofthese two letters gives three possible configurations
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  EARTHED NEUTRAL – TT InEarthed Neutral (TT) System, • the neutral from the main transformer is connected to the ground • All metallic parts of the equipment and loads are connected to another earth ground. 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 53
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  EXPOSED-CONDUCTIVE PARTS CONNECTED TO NEUTRAL–TN the neutral from the transformer is connected to the earth ground All metallic part of the equipment are connected to the neutral. 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 54  There are two ways to connect the metallic part to the neutral:  Through an earth wire connected to the neutral (TN-S)  connected directly to the neutral (TN-C).  An electric fault becomes a short circuit and circuit breaker or fuse will open the circuit.  This system has to be well design to be sure of the efficiency of the security.
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  TN-S 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 55
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  TN-C 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 56
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  UNEARTHED (OR IMPEDANCE- EARTHED)NEUTRAL –IT In IT system, the neutral from the transformer is isolated to the earth and the metallic parts of equipment are connected to the earth ground. In case of electric fault, there is no danger, but if there are two simultaneous faults, this will be a short circuit and proper device should open the faulty circuit 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 57
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  IT – 1STFAULT 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 58
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  IT – 2NDFAULT 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 59
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  THE EARTHED NEUTRAL –TT Thetransformer neutral is earthed; The frames of the electrical loads are also connected to an earth connection. The insulation fault current is limited by the impedance of the earth connections and the faulty part is disconnected by a Residual Current Device (RCD). 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 60
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  THE EARTHED NEUTRAL –TT 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 61
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  THE EARTHED NEUTRAL –TT 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 62
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  THE EARTHED NEUTRAL –TT Ra– Installation ground earth impedance Rb – Transformer (supply) ground earth impedance Rc- Fault impedance Uc – Contact voltage (50 V or 25 V) Ud – Fault voltage 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 63 𝐼𝑑 = V Ra + Rb + Rc 𝑈𝑑 = Ra ∗ Id
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  THE EARTHED NEUTRAL –TT Thesecurity device should open the circuit if Ud > Uc, in this case the rating value of the RCD/ELCB is I∆n≤ Uc/Ra with I∆n as the sensibility of the RCD/ELCB 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 64
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  THE EARTHED NEUTRAL –TT Protectionagainst direct contact: • The protection against direct contact is defined by the IEC 60449-1. The RCD/ELCB has to have a sensibility according to the threshold of sensation, 30 mA. 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 65
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  RCD AND SENSITIVITY Dueto its design a RCD/ELCB does not guaranty to open the circuit at the exact value of the sensibility. By standards, it has been defined that a RCD/ELCB will trip for a 𝐼∆𝑛 2 ≤ 𝐼𝐹 ≤ 𝐼∆𝑛 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 66
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  ELCB VS RCD RCDmeasure the phase and neutral current. If there is a difference, that means there is an earth leakage. Earth leakage can be detect even without earth pit connection. It is working even if there is an earth connection fault. ELCB measure the voltage between the earth and phase. It is required a good earth connection. It does not work if there is an earth connection fault. 02/06/2023 TOT-M02-LE-000-MT-0004-ver1 67
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  THANK YOU 71