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MINES

ENDORSEMENT

INTERVIEW

QUESTIONS

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MINES ENDORSEMENT INTERVIEW QUESTIONS

QUESTIUON 1- WHAT IS THE DEFINITION OF AN FLP MOTOR/ENCLOSURE? ANSWER: - DEFINITION 1.The FLP enclosure should be strong enough to withstand the explosion pressure without any injury or damage 2. The surface of the enclosure is machined and the air gap is made in such a way that flame cannot propagate or transmit via the flame path, that is, flanges, spindles and other jointed surfaces and will not ignite the external flammable atmosphere.

FLP motors and enclosures are generally made of cast iron or ductile iron (also a form of cast iron) or LM6 aluminium alloy or malleable iron. They are non-sparking metals and have good ductile strength The internal explosion containment is controlled by the tensile strength of these materials

MATERIAL TENSILE STRENGTH 1. MALLEABLE IRON 50,000 PSI

2. ALUMINIUM 30,000 PSI 3. GREY IRON 30,000 PSI

(NOTE: In many study materials it is given that the flame, after explosion, that will pass from inside to the outside of the enclosure is cooled to such an extent that it is incapable of igniting the surrounding flammable atmosphere. Flame-proofness generally depends upon the length of the flame path and air gap.

The length of the flame path, width of the air gaps and diametrical clearances depend upon the volume of the enclosure, the gas groups of different flammable gases and the type of joint.

The type of joint may be spigot, threaded, flanged, or cylindrical)

Types of Explosion-proof Construction – Appleton Products2014 Code Review Design of Explosion-proof Equipment

There is a rather common misconception that explosion-proof equipment is gas-tight. It would be inadvisable to make an entire wiring system gas-tight. Whenever an enclosure was opened for servicing apparatus, for example, the explosive mixture could enter and be trapped in the enclosure. The trapped atmosphere could then explode the instant the apparatus was again operated. The explosion could develop pressures sufficient to burst a gas-tight enclosure and allow flames to escape into the surrounding atmosphere.

The requirement is not that enclosures be gas-tight, but that they be designed and manufactured strong enough to contain an explosion and prevent the escape of flame or heat that could ignite surrounding atmospheres. Burned gases do escape from explosion-proof equipment, but their escape path has been engineered so the temperature of the escaping gas is well below its ignition point when it escapes into the surrounding atmosphere. Appleton explosion-proof products are designed to withstand a hydrostatic test of four times the maximum internal explosion pressure that could be developed from a gas explosion.

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QUESTION 2- WHAT IS 1) THE AIR GAP SIZE OR CLEARANCE MAINTAINED IN FLP ENCLOSURES? 2) WITHSTAND PRESSURE? 3) WIDTH OF THE JOINT?(OR FLAME PATH) 4) DISTANCE BETWEEN FLP ENCLOSURES AND OBSTRUCTIONS? ANSWER:-1. Generally the air gap or clearance is 0.3 mm. Air gap can be checked by using feeler gauges (Air gap and clearance have the same meaning. The gap between the main terminal box and the terminal box cover) 2. And tested to withstand 15 kg/cm2 3. Width of the joint 25 mm (from 6 mm to 40 mm depending upon the type of joint) 4. Minimum distance between the FLP enclosures and obstructions (that is, walls and pillars) A) For Group II A —10mm B) For Group II B –-30 mm C) For Group II C –-40 mm

MSHA requirements for demonstration of compliance include: • No discharge of visible flame from the enclosure and internal explosions cannot be transmitted to surrounding atmosphere • Enclosures must be strong enough to withstand an internal pressure of 150 PSI.

NOTE: - The air gap size depends upon 1) The volume of the enclosure, 2) The type of joint, whether it is a flanged or cylindrical or spigot joint and 3) The gas group TABLE 1-AIR GAPS FOR GROUP I, IIA AND IIB

Type of joint Width Of joint L in mm

maximum air gap in mm

For volume cm3 V<100

100<v<500 500<v<2000 V>2000

I IIA IIB I IIA IIB I IIA IIB I IIA IIB

Flanged, cylindrical

or spigot joints

6 9.5 12.5 25

0.3 0.3 0.2 0.35 0.3 0.2 0.4 0.3 0.2 0.5 0.4 0.2

- - - 0.35 0.3 0.2 0.4 0.3 0.2 0.5 0.4 0.2

- - - 0.8 0.8 0.8 0.4 0.3 0.2 0.5 0.4 0..2

- - - - - - 0.4 0.25 0.15 0.5 0.4 0.2

Cylindrical joints For shaft glands of rotating electrical Machines with

Sleeve bearings

6 9.5 12.5 25 40

0.30 0.30 0.20 0.35 0.30 0.20 0.4 0.35 0.25 0.5 0.4 0.3 0.6 0.5 0.4

- - - 0.35 0.30 0.20 0.4 0.3 0.20 0.5 0.4 0.25 0.6 0.5 0.3

- - - - - - 0.4 0.3 0.2 0.5 0.4 0.25 0.6 0.5 0.3

- - - - - - 0.4 0.2 - 0.5 0.4 0.2 0.6 0.4 0.25

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TABLE 2- AIR GAPS FOR GROUP C

Type of joint Width Of joint L in mm

maximum air gap in mm

For volume cm3 V<100

100<v<500 500<v<2000 V>2000

Flanged

joints

6 9.5 12.5 25

0.10 0.10 0.10 0.10

- 0.10 0.10 0.10

- - 0.04 0.04

- - - 0.04

Spigot joints

12.5 25 40

0.15 0.18 0.20

0.15 0.18 0.20

0.15 0.18 0.20

- 0.18 0.20

Cylindrical Joints Spigot joints

6 9.5 12.5 25 40

0.10 0.10 0.15 0.15 0.20

- 0.10 0.15 0.15 0.20

- - 0.15 0.15 0.20

- - - 0.15 0.20

Cylindrical joints for shaft

Glands for rotating electrical

machines with rolling element bearings

6 9.5 12.5 25 40

0.15 0.15 0.25 0.25 0.30

- 0.15 0.25 0.25 0.30

- - 0.25 0.25 0.30

- - - 0.25 0.30

QUESTION 3- WHAT IS THE RULE/REGULATION RELATING TO PRECAUTIONS IN MINES AND OIL AND GAS

FIELDS?

ANSWER:-1. Formerly IER 1956 rule 126 and now it is CEA REGULATIONS 2010, REGULATION 110.

(Go through IER 126 and CEA 110)

QUESTION 4:- WHAT ARE THE DUTIES OF THE ELECTRICAL SUPERVISOR?

ANXWER: - 1. To maintain daily log sheet as per IER 1956 rule 131-Annexure XII NOW As per C.E.A. Regulations 2010, regulation 115, Schedule XIII. 2. Other rules/regulations related to daily log sheet (A) IER 126, Sub rule 5 (i) and (ii) Now C E A regulations 110, sub regulations 8 and 9.(Relating to the steps to be taken when concentration of flammable gases is more than 20% of LEL and maintaining records).

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(B)IER 1956 116 (2) and (3) Now C E A Regulation 100, sub regulations (2) and (3) (Relating to checking of protective relays and maintaining records). (C)IER 131, sub rule 3(a)-relating to thorough examination of all the equipments including earth conductors. Now C E A REGULATION 115, 3(i) (D) IER 131, sub rule 3(b)-special examination-relating to examination of all the new equipments and the equipments re-erected. Now C E A REGULATION 115, 3 (ii)

QUESTION 5:- WHAT IF AN AUTHORIZED ELECTRICAL SUPERVISOR IS ON LEAVE OR ABSENT FOR LONG TIME? ANSWER: - If an authorized electrical supervisor is on leave or not available for more than 3 days the owner or agent of the mine should appoint a substitute certified supervisor. (See IER 1956 rule 131 sub rule 4 or C E A regulation 115, sub regulation 4)

QUESTION 6- IMPORTANT OMR 1984 REGULATIONS/OISD STANDARDS

1. OMR 1984 66/IER 1956, 126(5) AND (6)/CEA 2010,110(8) AND (9)-Precautions to be taken when

the concentration of flammable gas is more than 20% of LEL

2. OMR 1984 54/OISD STD 110 –Precautions to be taken during loading and unloading of diesel

tankers and precautions against static electricity hazards.

3. OMR 1984, 69- Precautions to be taken during welding

4. OISD STD 105/OISD 137- Hot work/cold work/electrical lock out and energization permit

OISD STD 105 ANNEXURE 1- COLD WORK PERMIT FORMAT

ANNEXURE II- HOT WORK PERMIT FORMAT

ANNEXURE III- ELECTRICAL DE-ENERGISATION/RE- ENERGISATION PERMIT FORMAT

QUESTION-7-DEFINE ZONE 0, ZONE 1 AND ZONE 2

ZONE 0 - 1. Hazardous media is always present in the atmosphere. 2. Where the presence of hazardous media that is gas/vapor is 10% or more than LEL for 1000 hours or more in a year. ZONE 1- 1. Hazardous atmosphere is present during normal operating conditions. 2. Where the presence of hazardous media that is gas/vapor is between 0.1% and 10% of L.E.L for 10 to 1000 hours in a year. ZONE 2- 1. Hazardous atmosphere is present during abnormal operating conditions. 2. Where the presence of hazardous media that is gas/vapor is between 0.01% and 0.1% of L.E.L for 10 hours in a year. REFERENCE-C.E.A.REGULATON (2010)-SUB-REGNS 8 AND 9 (ALSO SEE O.M.R.1984-REGN 66, SUB- REGNS 2 AND 3) (8) In an oil mine where concentration of inflammable gas exceeds twenty percent of its lowest explosive limit, the supply of electricity shall be cut-off immediately from all cables and apparatus lying within thirty meters of the installation and all sources of ignition shall also be removed from the said area and normal work shall not be resumed unless the area is made gas-free: Provided that such disconnection shall not apply to intrinsically safe environmental monitoring scientific instruments

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(9) Any such disconnection or re-connection of the supply shall be noted in the log sheet which shall be maintained in the form set out in Schedule-XIII and shall be reported to the inspector of mines. QUESTION 8-RECORDS TO BE PRODUCED DURING OISD/DGMS/TECHNICAL AUDITS? ANSWER:- Earth value register, IR value register, protective relay record, single line diagram, single line earth diagram, electric shock first aid notice with illustrative figures, 440v danger displays, list of electrical supervisors with Xerox copies of c licenses, etc., (REFER OISD STD 145) QUESTION 9-OTHER SAFETY MATERIALS LIKE RUBBER MATS, EMERGENCY LIGHTS, FLP/INTRINSIC SAFE TORCH LIGHTS FOR USE IN HAZARDOUS ZONES, EARTH ELECTRODES, APPROVED RUBBER GLOVES, ETC.,? QUESTION 10-USE OF MEGGER- WHETHER 500V OR 1000V? WHY 500V OR 1000V? ANSWER: - For voltages up to 650 volts, use of 500 volts megger is preferred and for medium voltages up to 11kv from 650 volts using 1000 volts megger is more preferable than 500 volts megger. Higher the voltage, the higher the megger range. SELECTION OF IR TESTERS/MEGGERS

1. IR testers/meggers are available in 500 v, 1000 v, 2500 v and 5000 v 2. The recommended range of the meggers are given below Voltage level megger voltage 650 V 500 v 11 KV 1000 v 33 KV 2500 v 66 KV and above 5000 v Test Voltage for meggering: When AC Voltage is used, The Rule of Thumbs -Test Voltage (A.C) = (2X Name Plate Voltage) +1000. (For cables, insulators and di-electric strength of oils) When DC Voltage is used (Most used in All Megger), Test Voltage (D.C) = (2X Name Plate Voltage). Equipment / Cable Rating DC Test Voltage

24V to 50V 50V to 100V 50V to 100V 100V to 250V 100V to 240V 250V to 500V

440V to 550V 500V to 1000V QUESTION 11-VOLTAGE RANGES THAT IS LV RANGE, MV RANGE, HV RANGE AND EHV RANGE? L.V=UP TO 250V, M.V=UP TO 11 KV FROM 450V, H.V= 11 KV AND ABOVE, E.H.V= 33 KV AND ABOVE I.E.R. 1956- RULE 54. Declared voltage of supply to consumer. Except with the written consent of the consumer or with the previous sanction of the State Government a supplier shall not permit the voltage at the point of commencement of supply as defined under rule 58 to vary from the declared voltage- (i) In the case of low or medium voltage, by more than 6 per cent, or; (ii) In the case of high voltage, by more than 6 per cent on the higher side or by more than 9 per cent on the lower side, or;

(iii) In the case of extra-high voltage, by more than 10 per cent on the higher side or by more

than 12.5 per cent on the lower side.

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QUESTION 12-WHY 160 W M V LAMPS ARE USED IN VERTICAL POSITION ONLY? ANSWER: - The mercury vapor in the MV lamp is illuminated due to the arc produced in the arc gap between the electrodes and the arc gap may be from 0.25 mm to several mm depending upon the lamp power. Mercury vapor lamps operate with the anode at the bottom. This position ensures proper vaporization of the mercury. Hence to increase life time and maintain better arc stability the 160 w M V lamps should be fixed or positioned vertically or otherwise as per manufacturer’s instruction NOTE: - 1. ARC LAMPS SHOULD BE POSITIONED VERTICALLY OR HORIZONTALLY ONLY AS INSTRUCTED BY THE MANUFACTURER. IF IT IS MENTIONED UNIVERSAL, THEN THE LAMP CAN BE FITTED IN ANY POSITION 2. THESE ARE ALSO CALLED MLL- MIXED LIGHT LAMPS- MEANING THAT (A) THEY CAN BE USED AS AND IN PLACE OF INCANDESCNT LIGHTS DIRECTLY WITH 220V SUPPLY AND HAVING NO GEAR BOX WITH MERCURY VAPOR. (B) THEY CAN ALSO BE CALLED ARC LAMPS WITH THE MERCURY VAPOR GIVING ILLUMINATION DUE TO ARC IN THE ELECTRODES (C) AND ALSO THEY ARE MERCURY VAPOR LAMPS AS THE VAPOR IS MERCURY VAPOR QUESTION 13- HOW THE 160 W MV MLL LAMPS WILL LOOK LIKE WHEN THE VAPOR GETS OVER HEATED AND FIRES UP? ANSWER: - When the mercury vapor in the MLL lamp gets over heated and fires up, the lamp will emit violet color beam or ray for one or two minutes and the lamp will cease to glow after that ( (or) Sometimes the lamp will be flickering in bright white for one or two minutes and the lamp will cease to glow. The lamp will not burst. QUESTION 14- SOME STATUTORY AUTHORITIES AND ORGANISATIONS THAT GOVERN RULES AND REGULATIONS REGARDING MINES AND OIL INDUSTRIES? ANSWER: - 1. D.G.M.S---- DIRECTOR GENERAL OF MINES SAFETY H.Q-DHANBAD 2.O.I.S.D-----OIL INDUSTRIES SAFETY DIRECTOREATE H.Q-NOIDA, U.P. 3. I.E.R 1956—INDIAN ELECTRICITY RULES 1956 I NOW CENTRAL ELECTRICITY AUTHORITY REGULATIONS 2010

4. CENTRAL MINES RESEARCH INSTITUTE 5. CENTRAL FUEL RESEARCH INSTITUTE

BOTH COMBINED AND NOW CENTRAL INSTITUTE OF MINES AND FUEL RESEARCH H.Q-DHANBAD

6. C.C.E--- CHIEF CONTROLLER OF EXPLOSIVES I NOW P.E.S.O---- PETROLEUM AND EXPLOSIVES SAFETY ORGANISATION H.Q- NAGPUR 7. O.M.R. 1984---- OIL MINES REGULATIONS 1984 8. CPRI- CENTRAL POWER RESEARCH INSTITUTE, BANGALORE (WHERE INGRESS PROTECTION TESTING IS DONE) QUESTION 15- SAMPLE CALIBRATION REPORT OF MULTI GAS DETECTOR (SCIENTIFIC INSTRUMENTS M 40

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ANSWER: -

SENSOR TYPE CAL. GAS LOW ALARM HIGH ALARM TWA ALARM STEL ALARM

H2S H2S 10 PPM 20 PPM 10 PPM/8 HRS 15 PPM/15 MIN

L.E.L L.E.L 10% OF L.E.L 20% OF L.E.L - -

TEST GAS USED: - 0.5 LITRE/CANNISTER @ 120 KG/CM2 FILLING PRESSURE

1. PENTANE 0.36% (OF TOTAL VOLUME) 25.71% OF L.E.L (L.E.L OF PENTANE IS 1.4%) 2. H2S 27 PPM ----- 3. CO 105 PPM ----- 4. OXYGEN 21.19% ----- 5. NITROGEN BALANCE -----

QUESTION16– VARIOUS SPECIAL PURPOSE MOTORS FOR MINES AND OIL/GAS FIELDS? ANSWER -1. FLAME PROOF - TYPE D 2. INCREASED SAFETY-TYPE E 3. INTRINSIC SAFETY- TYPE I 4. ENCAPSULATED- TYPE M 5. NON INCENDIVE OR NON SPARKING-TYPE N 6. OIL IMMERSION-TYPE O 7. PUIRGED/PRESSURIZED-TYPE P

8. SAND OR POWDER FILLED-TYPE Q 9. SPECIAL PROTECTION-TYPE S 10. HERMATICALLY SEALED

QUESTION .17-ENCLOSURES AND DEVICES FOR ZONE 0. 1 AND 2? FOR ZONE 0

1. INTRINSIC SAFE-TYPE I 2. ENCAPSULATED-TYPE M 3. SPECIAL PROTECTION-TYPE S

These devices can also be used in lesser degree zones 1 and 2. FOR ZONE 1

1. INCREASED SAFETY-TYPE E 2. POWDER OR SAND FILLED-TYPE Q 3. FLP-TYPE D 4. OIL IMMERSION-TYPE O 5. PRESSURIZED-TYPE P

These devices can also be used in zone 2 FOR ZONE 2

1. NON INCENDIVE OR NON SPARKING-TYPE N 2. INCREASED SAFETY-TYPE- E

REFERENCE- C.E.A. REGULATION -110. PRECAUTIONS WHERE GAS EXISTS. – SUB-REGN 3, 4 AND 5 (RELATING TO EQUIPMENTS IN ZONE 2, ZONE 1 AND ZONE 0)

C.E.A. REGN 2010, REGN 110, SUB-REGN (3) - In any oil mine or oil-field, at any place within the zone-2 hazardous areas-

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(i) All signaling and telecommunication, remote control and insulation tester circuits shall be so constructed, installed, operated, protected and maintained as to be intrinsically safe; (ii) All cables shall be so constructed, installed, operated and maintained as to prevent risk of open sparking; (iii) All apparatus including portable and transportable apparatus shall have the following types of enclosures conforming to the relevant Indian Standards, namely:- (a) Flame-proof enclosure type’d’ or (b) Pressurized enclosure type 'p' or (c) Sand filled apparatus type 'q' or (d) Increased safety enclosure type 'e', 'n' and 'o' (iv)All electric lamps shall be enclosed in increased safety enclosure type 'e’ SUB-REGN (4) In any oil mine or oil-field, at any place within the zone-1 hazardous areas- (i) all signaling and telecommunication, remote control and insulation tester circuits shall be so constructed, installed, operated, protected and maintained as to be intrinsically safe; ii) All cables shall be so constructed, installed, operated and maintained as to prevent risk of open sparking; (iii) All apparatus including portable and transportable apparatus shall have the following types of enclosures conforming to the relevant Indian Standards, namely: (a) Flame-proof enclosure type 'd’ or (b) Pressurized enclosure type 'p' or (c) Sand filled apparatus type ‘q' (iv) All electric lamps shall be enclosed in flame-proof enclosures. SUB-REGN (5) In any oil mine at any place within zone-0 hazardous area no electrical equipment shall be used and where it is not practicable, intrinsically safe apparatus are only to be used with the prior approval of the Inspector. (PROVISION OF OIL MINE REGULATION FOR USE OF ELECTRICAL EQUIPMENT IN HAZARDOUS AREA) OMR 75(1): No electrical appliances equipment or machinery including apparatus shall be used in zone ’O’ hazardous area. OMR (75) : The chief Inspector may from time to time by notification in the official gazette, specify appliances, equipment and machinery that are or may be used in zone-1 and zone-2 hazardous area which will be such type, standard and make as approved by the chief Inspector by a general or special order in writing. Where any such appliances, equipment or machinery has been specified by the chief Inspector, any appliances equipment or machinery other than approved by chief Inspector shall not be used in such hazardous area. The gazette notification governing use of electrical equipment in zone-1 and zone-2 area is given separately.) NOTE: - ALL SIGNALING AND TELECOMMUNICATION, REMOTE CONTROL AND INSULATION TESTER CIRCUITS SHALL BE SO CONSTRUCTED, INSTALLED, OPERATED, PROTECTED AND MAINTAINED AS TO BE INTRINSICALLY SAFE (WHETHER IT IS ZONE 0, Z0NE 1 OR ZONE 2)

QUESTION 18- METHODS OF PROTECTION?

1. Designed to prevent any means of ignition arising— 1. Non sparking-type n 2. Increased safety-type e

2. Designed to limit the ignition energy of the circuit— 1. Intrinsic safety-type i

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3. Designed to prevent the flammable mixture reaching the source of ignition- 1. Encapsulation- type m

2. Pressurization-type p 3. Oil immersion-type o 4. Ex nR- restricted breathing 4. Designed to prevent propagation or transmission of flame- 1 Flame proof-type d 2. Powder or sand filled-type q QUESTION 19- WHAT ARE THE DIFFERENCES BETWEEN FLP AND EXPLOSION PROOF MOTORS? EX-PROOF FLAME PROOF

1. In America in NEC method the motor In other countries, including India, in

is called Explosion- proof IEC method, it is called Flame-proof

2. The test pressure is 4 times the The test pressure is 1.5 times the

reference pressure reference pressure

3. Hence it is Heavier Due to lower test pressure it is Lighter

4. Heat rise is not a consideration Factor which limits the components inside

5. The enclosures may be used in Enclosures are designed to work between 40 deg C

Extreme cold weather conditions and -20 deg Conly

Below -20 deg C and upto -50 deg C

QUESTION 20-SOME INTERNATIONAL REGULATORY BODIES? 1. I.E.C.- INTERNATIONAL ELECTRO TECHNICAL COMMISSION 2. N.E.C.- NATONAL ELECTRIC CODE

3. M.S.H.A.- MINES SAFETY AND HEALTH ADMINITRATION

4. U/L-UNDER WRITERS LABORATORY

5. N.EM.A- NATIONAL ELECTRIC MANUFACTURERS ASSOCIATION

6. N.F.P.A- NATIONAL FIRE PROTECTION ASSOCIATION

7. C.S.A.-CANADIAN STANDARDS ASSOCIATION

8. C.E. - CONFIRMITY TO EUROPEAN STANDARDS

9. ATEX-EXPLOSIVE ATMOSPHERE

10. CENELEC-EUROPEAN COMMITTEE FOR ELECTROTECHNICAL STANDARDISATION

11. FM- FACTORY MANUAL

12. CEC- CANADIAN ELECTRIC CODE

QUESTION21. ACCIDENT REPORTING?

As per Indian Electricity Act 2003, Form A of Intimation of Accidents 2004 should be submitted

to the Inspector within 48 hours of serious or fatal accident and the same should be intimated

through telephone or fax message within 24 hours

(NOTE- Before it was IER 1956 rule 44 A, Annexure XIII)

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”REPORTABLE INJURY” means any injury other than a serious bodily injury which involves, or in all probability will involve, the enforced absence of the injured persons from work for a period of seventy-two hours or more. “SERIOUS BODILY INJURY” means any injury which involves; or in all probability will involve the permanent loss of any part or section of a body or the use of any part or section of a body, or the permanent loss of or injury to the sight or hearing or any permanent physical incapacity or the fracture of any bone or one or more joints or bones of any phalanges of hand or foot ELECTRICITY ACT 161 NOTICE OF ACCIDENTS AND INQUIRIES. 161. (1) If any accident occurs in connection with the generation, transmission, distribution, supply or use of electricity in or in connection with, any part of the electric lines or electrical plant of any person and the accident results or is likely to have resulted in loss of human or animal life or in any injury to a human being or an animal, such person shall give notice of the occurrence and of any such loss or injury actually caused by the accident, in such form and within such time as may be prescribed, to the Electrical Inspector or such other person as aforesaid and to such other authorities as the Appropriate Government may by general or special order, direct. (2) The Appropriate Government may, if it thinks fit, require any Electrical Inspector, or any other person appointed by it in this behalf, to inquire and report- (a)As to the cause of any accident affecting the safety of the public, which may have been occasioned by or in connection with, the generation, transmission, distribution, supply or use of electricity, or (b) As to the manner in, and extent to, which the provisions of this Act or rules and regulations made there under or of any license, so far as those provisions affect the safety of any person, have been complied with. (3) Every Electrical Inspector or other person holding an inquiry under sub-section (2) shall have all the powers of a civil court under the Code of Civil Procedure, 1908 for the purpose of enforcing the attendance of witnesses and compelling the production of documents and material objects, and every person required by an Electrical Inspector be legally bound to do so within the meaning of section 176 of the Indian Penal Code. QUESTION22. LIMITING FAULT CURRENT AND USE OF NEUTRAL CURRENT GROUNDING RESISTOR? As per C.E.A.REGULATIONS 2010 REGULATION 100, the fault current should not be more than 1. 750mA for voltages exceeding 250 volts and up to 1100 volts in mines and oil fields 2. And 50 A for voltages more than1100 volts and up to 11 KV in open cast mines

The magnitude of the earth fault currents may be limited within these limits by using suitably designed restricted neutral system of the power supply USE OF N.G.Rs SATISFY THIS RULE MAKING THE NEUTRAL

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1. AN IDEAL 0 OHMS NEGATIVE POTENTIAL EARTHING CONDUCTOR AND 2. MAKING THE EARTH FAULT RELAY MORE SENSITIVE TO EARTH FAULTS

QUESTION23-WELL GLASS FITTING GLASS IS MADE OF? Toughened glass of 6.3mm or more tested to withstand impact energy of 7 joules QUESTION 24-UNDERSTANDING LEL READING OF GAS DETECTORS? Gas detectors are calibrated to read % LEL For example if the reading is 5 and if the reading is for natural gas, then the % of concentration of natural gas in atmosphere is, Reading X LEL of natural gas, (LEL is 5% for methane and natural gas) =5% x 5/100 = 0.25% Example 2- If the reading is 8 and if the reading is for hydrogen, then the concentration of hydrogen in atmospheric volume is =8% X 4% (LEL of Hydrogen is 4%) =8% x 4/100=0.32% QUESTION 25-WHAT IS STREAMING CURRENT? STREAMING CURRENT- IT is the current which originates when an electrolyte is driven by pressure gradient through a channel or a pipe with charged walls In other words, it is the static electricity generated when a liquid flows through a pipe driven by a pressure gradient with charged walls. REFER-O.I.S.D.R.P.110-RECOMMENDED PRACTICES ON STATIC ELECTRICITY NOTE: - THE PROTECTION AGAINST THIS STATIC ELECTRICITY CHARGES IN UNDER GROUND, UNDERSEA OR CROSS COUNTRY PIPE LINES IS CALLED CATHODIC PROTECTION QUESTION26-WHAT IS AIR GAP AND MAX.EXPERIMENTAL SAFE GAP? Air Gap means the distance between the corresponding surfaces of a flame path. For cylindrical surfaces, the gap is the diametrical clearance (i.e. the difference between the two diameters) Maximum Experimental Safe Gap (MESG) means the largest gap size in a series of tests, using a standardized enclosure under laboratory conditions, which does not permit the ignition of a flammable mixture inside of an enclosure to cause ignition of an explosive mixture surrounding the enclosure. QUESTION 27-DEFINE INTRINSIC SAFETY? Intrinsically safe: Incapable of releasing enough electrical or thermal energy under normal or

abnormal conditions to cause ignition of a flammable mixture of methane or natural gas and air of

the most easily ignitable composition. Available energy from any component must be less than

about 0.25micro Joules.

Example- Gas detectors, instruments and meters

1) NOTE: - In case the voltage, current or power exceeds 50 volts, 150 mA or 3 watts

respectively, then the device cannot be considered as intrinsically safe.

2) NOTE: - In mines the voltage limit for intrinsic safety is 30 volts

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QUESTION 28-MAXIMUM EXPERIMENTAL SAFE GAP AND MINIMUM IGNITION CURRENT?

GAS GROUP MESG MIC II A 0.9 mm 0.8A or more II B 0.5 mm to 0.9 mm 0.5 TO 0.8A III B less than 0.5 mm less than 0.45A QUESTION 29-DETERMINATION OF EXPLOSION PRESSURE?

GROUP I ENCLOSURE 9.8+ OR – 0.5% METHANE WITH AIR GROUP II A ENCLOSURE 4.6 + OR – 0.3% PROPANE WITH AIR GROUP II B ENCLOSURE 8% ETHYLENE OR 24% OF 85/15 HYDROGEN/METHANE OR BETWEEN 3 TO 4.2% OF ETHYL ETHER WITHAIR GROUP II C ENCLOSURE 14% ACETYLENE OR 31% HYDROGEN WITH AIR

As per the above table, the test gases with air are filled in the enclosures and ignited with spark plug and a reference pressure is arrived at (10 kg/cm2, for example) for respective gas groups and the enclosure is finally tested for 1.5 times the reference pressure i.e., 15 kg/cm2 QUESTION 30-EXPLAIN INGRESS PROTECTION? (Details of Ingress Protection can be got freely from internet and other sources) QUESTION31- EQUIPMENT CATEGORIES FOR MINES AND OILFIELDS EQUIPMENT CATEGORIES FOR MINES AND OILFIELDS ARE AS FOLLOWS

1. GROUP 1- M1 (FOR MINES) 2. GROUP 2/M2- M2 (FOR MINES) AND

GROUP 2 A, B AND C (FOR SURFACE INDUSTRIES) GROUP 1/M1- For underground mines or surface installations of such mines where there is a hazard of firedamp or combustible dust explosion. Equipment is required to remain functional even in the event of rare incidents relating to equipment

A) In the event of failure of one means of protection, at least an independent second means provides the required level of protection

B) The required level of protection is assured in the event of two faults occurring independently of each other

GROUP 2/M2- For underground mines of such mines where there is a hazard of firedamp or combustible dust explosion.

A) The equipment is required to be de energized in the event of explosive atmosphere

GROUP 2 equipments are again sub divided into three categories with respect to surface industries as

1) CATEGORY 1 or CATEGORY A (or a) with the highest level of protection for use in zone 0 2) CATEGORY 2 or CATEGORY B (or b) with the level of protection for use in zone 1 3) CATEGORY 3 or CATEGORY C (or c) with the level of protection for zone 2

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For example ia means i denotes the type of equipment that is intrinsic safe And a denotes the motor grouping that it is intended for use in zone 0 NOTE: - In mines there are only two hazardous areas namely

1. Extremely highly hazardous (M1-Motor grouping) and 2. Highly hazardous( M2-Motor grouping)

QUESTION32- PARAMETERS FOR SELECTING A MOTOR FOR HAZARDOUS LOCATIONS The following are the parameters for consideration for selection of motors in hazardous areas.

1. The type of hazard (whether gas, vapor/oil or dust or in other words Group I, Group IIA, IIB or IIC or Group IIIC)

2. The likelihood of hazard (whether zone 0, zone 1 or zone 2) 3. The ignition temperature of the gas involved or being dealt with 4. The temperature class of the apparatus(whether t1,t2,t3,t4,t5,or t6) 5. The environment the equipment will operate

A) Whether the environment is extremely high or low temperatures(like in Middle East or Norway)

B) if the weather condition is arduous(like in off shore or marine installations) C) immersion in water(like in dry docks) D) whether the atmosphere is subject to dusty conditions

Other environmental parameters 1) ambient temperature 2) how much liquid or dust the equipment will subject to and how long 3) any impact the equipment will subject to in its service life 4) any chemicals/vapors that could attack the plastic parts

Idea on N E M A and IP ratings and certification is necessary for these parameters NOTE: - 1. In American method, N E M A rating system is followed and

2. In I E C method, Ingress Protection system is followed for environmental protection of equipments

QUESTION 33: - ARE SODIUM VAPOR LAMPS SUITABLE FOR HAZARDOUS AREAS? IF NOT WHY? No. Because the sodium in these lamps is a highly volatile substance. When exposed to air the sodium may explode. (The sodium lamp should not be disposed of normally like the normal garbage is disposed of. There have been many cases of garbage trucks catching fire when the bulbs in the back broke. Sodium lamps also contain mercury. The newer LPS lamps contain less mercury than before, but this has affected performance negatively.) QUESTION 34: - WHAT IS THE PRECAUTION TO BE TAKEN WHEN USING SIGNALLING, TELECOMMUNICATION DEVICES AND DETECTORS IN HAZARDOUS AREAS? C.E.A. REGULATION 2010, REGN 112. SIGNALING. Where electrical signaling is used,- (i) Adequate precautions shall be taken to prevent signal and telephone wires coming into contact with other cables and apparatus; (ii) The voltage used in any one circuit shall not exceed 30 V;

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(iii) Contact-makers shall be so constructed as to prevent the accidental closing of the circuit; and (iv) Bare conductors, where used shall be installed in suitable insulators. (ALSO REFER CEA REGULETION 2010, REGN 110, SUB REGNS 3, 4 AND 5) QUESTION 35: - VOLTAGE LIMITS IN HAZARDOUS AREAS IN MINES AND OIL FIELDS?

C.E.A.REGULATIONS 2010, REGN 103. VOLTAGE LIMITS: - Electricity shall not be transmitted into a mine at a voltage exceeding 11000 Volts and shall not be used therein at a voltage exceeding 6600 Volts: Provided that- (i) Where hand-held portable apparatus is used, the voltage shall not exceed 125 V; (ii) Where electric lighting is used,- (a) In underground mines, the lighting system shall have a mid or neutral point connected with earth and the voltage shall not exceed 125 V between phases; (b) on the surface of a mine or in an, open cast mine, the voltage may be raised to 250 V, if the neutral or the midpoint of the system is connected with earth and the voltage between the phases does not exceed 250 V; (iii) Where portable hand-lamps are used in underground working of mine, the voltage shall not exceed 30 Volts. QUESTION 36: PRECAUTIONS AGAINST LIGHTING, OVER HEAD LINES, COMMUNICATION AND FIRE C.E.A. REGULATIONS 2010, REGULATION 97. LIGHTING, OVERHEAD LINES, COMMUNICATION AND FIRE PRECAUTIONS.-

(1) In a mine illuminated by electricity, one or more flame safety lamps, or other lights approved by the inspector of mines, shall be maintained in a state of continuous illumination in all places where failure of the electric light at any time shall be prejudicial to safety.

(2) Efficient means of communication shall be provided in every mine between the point where the switch gear under sub-regulation (1) regulation 105 is erected, the shaft bottom and other distributing centers in the mines.

(3) Fire extinguishing appliances of adequate capacity and of an approved type shall be installed and properly maintained in every place in a mine containing apparatus, other than cables, telecommunication and signaling apparatus.

(4) In case of mines, minimum clearance above ground of the lowest conductor of

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Overhead lines or overhead cables where dumpers or trackless vehicles are being operated shall not be less than twelve meters in height from the ground across the road where dumpers or trackless vehicles cross.

QUESTION37: - HUMAN BODY RESISTANCE AND THE ELECTRIC CURRENT EFFECTS IN THE HUMAN BODY?

BODY RESISTANCE IN OHMS/CM2 The resistance of human skin varies from person to person and fluctuates between

different times of day. The NIOSH states "Under dry conditions, the resistance offered by the human body may be as high as 100,000 Ohms.

Wet or broken skin may drop the body's resistance to 1,000 Ohms," adding that "high-voltage electrical energy quickly breaks down human skin, reducing the human body's resistance to 500 Ohms.

The International Electro technical Commission gives the following values for the total body impedance of a hand to hand circuit for dry skin, large contact areas, 50 Hz AC currents (the columns contain the distribution of the impedance in the population percentile; for example at 100 V 50% of the population had an impedance of 1875Ω or less):[16]

Voltage 5% 50% 95% 25 V 1,750 Ω 3,250 Ω 6,100 Ω 100 V 1,200 Ω 1,875 Ω 3,200 Ω 220 V 1,000 Ω 1,350 Ω 2,125 Ω 1000 V 700 Ω 1,050 Ω 1,500 Ω A rough value for the internal resistance of the human body is 300-1,000 Ohms. Naturally, the resistance also depends on the path that electricity takes through the body - if the electricity goes in the left hand and out the right foot, then the resistance will be much higher than if it goes in and out of adjacent fingers. Electrocuted in real life, the body's resistance drops as the skin is burned. To determine a person's total resistance, just add together the resistance of each part of the body - remember that the electricity must pass through the skin twice (on the way in and on the way out), so the total resistance is: R total = R skin (in) + R internal + R skin (out)

HOW ELECTRICAL CURRENT AFFECTS THE HUMAN BODY Three primary factors affect the severity of the shock a person receives, when he or she is a part of an electrical circuit:

Amount of current flowing through the body (measured in amperes). Path of the current through the body. Length of time the body is in the circuit.

Other factors that may affect the severity of the shock are: The voltage of the current. The presence of moisture in the environment. The phase of the heart cycle when the shock occurs. The general health of the person prior to the shock.

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Effects can range from a barely perceptible tingle to severe burns and immediate cardiac arrest. Although it is not known the exact injuries that result from any given amperage, the following table demonstrates this general relationship for a 60-cycle, hand-to-foot shock of one second's duration:

CURRENT LEVEL

Milli amperes Probable Effect on Human Body

1 mA Perception level. Slight tingling sensation. Still dangerous under certain conditions.

5mA Slight shock felt; not painful but disturbing. Average individual can let go. However, strong involuntary reactions to shocks in this range may lead to injuries.

6mA - 16mA Painful shock, begin to lose muscular control. Commonly referred to as the freezing current or "let-go" range.

17mA - 99mA Extreme pain, respiratory arrest, severe muscular contractions. Individual cannot let go. Death is possible.

100mA - 2000mA Ventricular fibrillation (uneven, uncoordinated pumping of the heart.) Muscular contraction and nerve damage begins to occur. Death is likely.

More than 2000 mA Cardiac arrest, internal organ damage, and severe burns. Death is probable.

1. THE HIGHER THE VOLTAGE THE MORE DANGEROUS 2. THE LOWER THE BODY RESISTANCE THE MORE DANGEROUS 3. TTHE LETHAL CURRENT FOR MEN IS HIGHER THAN THAT FOR WOMEN

QUESTION 38: - ILLUMINATION AND LIGHTING IN MINES AND OIL FIELDS

O.M.R. 1984, REGN 83. GENERAL LIGHTING (1) Adequate general lighting arrangements shall be provided during working hours at the following places - (a) Where the natural lighting is insufficient; (b) Derrick floor; (c) Driller’s stand and control panel; (d) Monkey board; (e) Every engine and pump house; (f) Derrick sub-structure near blowout preventer controls; (g) Every place where persons are to work; (h) Every means of escape, access or egress; (2) The lighting provided in a mine shall as far as possible be so arranged as to prevent glare or eye strain. 84. ELECTRIC LIGHTING (1) Every electrical lighting apparatus shall be of a type approved by the Chief Inspector.

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(2) The lighting system installed in the mine shall comply with the provisions of the Indian Electricity Rules, 1956. (3) Every electrical lighting apparatus shall be so fitted as to protect it from accidental damage. 85. STANDARDS OF LIGHTING The Chief Inspector may from time to time by notification in the Official Gazette specify the standards of lighting to be provided in any specified area or places in a mine. 86. EMERGENCY LIGHTING Adequate number of self - contained portable hand lamps of approved type shall be made and kept available for immediate use in emergency.

QUESTION 39: - PROTECTION AGAINST NOISE O.M.R.1984 REGULATION 91. PROTECTION AGAINST NOISE (1) The owner, agent or manager shall take reasonably practicable means to reduce the noise level and to reduce the exposure of work persons to noise. (2) No person shall enter or be allowed to enter without appropriate ear protection, an area in which the sound level is 115 dB (A) or more. (3) No person shall enter or be allowed to enter an area in which the sound level is 140 dB (A) or more. (4) The Chief Inspector may, from time to time by notification in the Official Gazette, specify the permissible noise exposure in any area or place in a mine. QUESTION 40: - AREA CLASSIFICATION IN HAZARDOUS MINES CLASSIFICATION OF HAZARDOUS AREAS IN OIL MINES (UNDER REGULATION 74 OF OIL MINES REGULATION 1984. NO. 1(6)2001-GENL/3604-3753 DATED 12TH SEPT 2001)

A. WELL HEAD AREA

(i) When the derrick is not enclosed and the substructure is open to ventilation, the area in all directions from the base of rotary table extending up to 3m shall be zone-2 hazardous area. Any cellar, trenches and pits below the ground level shall be zone-1 hazardous area, the area lying within 3m in horizontal direction from the edge of any cellar, trenches or pit and 0.5m vertically above the cellar shall be zone-2 hazardous area.

(ii) When the derrick floor and substructure are enclosed, the enclosed substructure below the derrick floor including cellar, pits or sumps below the ground level, shall be zone-1 area, the enclosed area above the derrick floor shall be zone-2 hazardous area.

Mud tank / Channel The free space above the level of mud in tank and channel shall be zone-1 hazardous area; the area in a radius of 3m in all directions from the edge of mud tank and channel shall be zone-2 hazardous area. Shale Shaker

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(a) The area within a radius of 1.5m in all directions from the shale shaker in open air shall be

zone-1 hazardous area. The area beyond 1.5m and up to 3m in all directions from the shale shaker shall be zone-2 hazardous area.

(b) When the shale shaker is located in an enclosure, the enclosed area shall be zone-1 hazardous area to the extent of the enclosure. The area outside Shale shaker and up to 1.5m in all directions from the shale shaker shall be Zone-2 hazardous area.

Degasser

(a) The area within a radius of 1.5m from the open end of the vent extending in all directions shall be zone-1, the area beyond 1.5m and up to 3m in all directions from the open end of the vent shall be zone-2 hazardous area.

Desander and Desilter The area within a radius of 1.5m in all directions from the desander and desilter located in open air shall be zone-2 hazardous area. Effluent Pit and open Sump: The free space above the level of flammable liquid within the effluent pit or sump shall be zone-1 hazardous area; the free space lying up to 3m in horizontal direction from the edge of any effluent pit or sump and 0.5m vertically above the effluent pit or open sump shall be zone-2 hazardous area.

B. OIL WELLS

(1) Flowing Well An area below the ground level shall be zone-1 hazardous area; the area lying up to 3m in horizontal directions from the edge of any cellar, trenches or pit and 0.5m vertically above the cellar, trenches or sump shall be zone-2 hazardous area. (2) Artificially Lifted Well

(a) An area in wells equipped with sucker-rod pump up to 3m above the ground level and up to 3m horizontally in all directions from the well-head shall be zone-2 hazardous area. In case of cellar, an area below the ground level shall be zone-1 hazardous area; the area lying up to 3m in horizontal direction from the edge of any cellars and o.5m vertically above the cellars shall be zone-2 hazardous area.

(b) The area in wells driven with submersible electric motor driven pumps or hydraulic sub-surface pump or gas lift well shall be same as specified in clause B(1) when the well is provided with cellar or sump.

(3)Well under production test:

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The area within a radius of 8m from an open discharge of petroleum bearing fluid from a well under production test shall be zone-1 hazardous area. The area beyond zone-1 hazardous area for a further distance of 8m in all directions shall be zone-2 hazardous area. Well servicing operations: The area within a radius of 10m in all directions from a well pulling and other such well servicing shall be zone-2 area. Provided that where cellar or sump is present, the area with the cellar or sump shall be zone-1 hazardous area. And the area lying up to 3m horizontal direction from the edge from any cellars or sump and 0.5m vertically above the cellars or sump shall be zone-2 hazardous area. Gas Vent: The area within a radius of 1.5m from open end of the vent extending in all directions shall be zone-1 hazardous area, and area lying within a radius beyond zone-1 hazardous area upto 3m of the vent shall be zone-1 hazardous area.

C. OIL AND GAS PROCESSING AND STORAGE EQUIPMENT:

(1) Oil-gas separation Vessel, Fired vessel, Dehydrator, stabilizer hydrocarbon recovery unit;

(a) The area within a radius of 3m from any oil-gas separation vessel, fired vessel dehydrator, stabilizer and hydrocarbon recovery unit shall be zone-2 hazardous area

(b) Any trench or pit below ground level shall be zone-1 hazardous area and the area lying up to 3m in horizontal direction from the edge of any trench or pit shall be zone-2 hazardous area

Gas Vent The area within a radius of 1.5m from open end of the vent extending in all directions shall be zone-1 hazardous area, and the area lying within a radius beyond zone-1 hazardous area upto 3m of the vent shall be zone-2 hazardous area. Relief Valve: The area within a radius of not less than 3m from discharge of relief valve extending in all directions shall be zone-2 area subject to the condition that there shall be no electrical equipment in the direct path of discharge from relief valve. Pig Trap The area within radius of 1.5m of pig launching/receiving trap extending in all directions shall be zone-1 area. The area lying beyond zone-1 hazardous area and up to a radius of 3m in all directions from pig launching/receiving trap shall be zone-2 hazardous area. Pumps/Gas Compressors:

(a) Where a pump handling flammable liquid or gas compressor is located in open, air or well ventilated shed without walls, the area lying up to 3m in all directions from pump or compressor shall be zone-2 hazardous area.

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(b) Where a pump or compressor is located in an adequately ventilated building, the

entire interior of such building including an area within 1.5m of the vent shall be zone-2 hazardous area.

(c) Pits, sumps, trenches below the ground level shall be zone-1 hazardous area and the area lying up to 3m in horizontal direction from the edge of any trench or pit and 0.5m vertically above the pit sumps or trenches shall be zone-2 hazardous area

Storage Tank: (a) In case of floating roof tank, the space above the floating roof and inside the enclosure up to top level of enclosure wall shall be one zone-1 hazardous area; the area beyond zone-1 hazardous area and up to a radius of 4.5m in all directions from tank shell and shell top be zone-2 area. In case of a dyke, zone-2 hazardous area shall extend vertically up to the height of the dyke and horizontally up to the physical boundary of the dyke.

(b) In case of fixed roof tank, the area inside the tank and within a radius of 1.5m from all openings including breather valve, dip hatch, thief hatch and safety valve shall be zone-1 hazardous area; the area beyond zone-1 hazardous area and upto radius of 3m in all directions from shell and roof of the tank shall be zone-2 hazardous area. In case of a dyke, the sump in the dyke and horizontally up to physical boundary of the dyke shall be zone-2 hazardous area.

D.GENERAL Where ever sampling cock or feed valve is fitted, the area up to 1.5m in all directions from the release point shall be zone-2 hazardous area. PROVISION OF OIL MINE REGULATION FOR USE OF ELECTRICAL EQUIPMENT IN HAZARDOUS AREA OMR 75(1): No electrical appliances equipment or machinery including apparatus shall be used in zone ’O’ hazardous area.(Intrinsically safe, TYPE I or encapsulated, TYPE M devices may be used if practicable and available) OMR 75(2) : The chief Inspector may from time to time by notification in the official gazette, specify appliances, equipment and machinery that are or may be used in zone-1 and zone-2 hazardous area which will be such type, standard and make as approved by the chief Inspector by a general or special order in writing. Where any such appliances, equipment or machinery has been specified by the chief Inspector, any appliances equipment or machinery other than approved by chief Inspector shall not be used in such hazardous area. The gazette notification governing use of electrical equipment in zone-1 and zone-2 area is given separately. QUESTION 41: - SOME ELECTRICAL SAFETY AND DISTANCE FROM HV LINES OCCUPATIONAL HEALTH AND SAFETY REGULATION

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Table 1

COLUMN 1 VOLTAGE

COLUMN 2 MINIMUM DISTANCE

MINIMUM APPROACH DISTANCE FOR WORKING CLOSE TO EXPOSED ELECTRICAL EQUIPMENT OR CONDUCTORS

PHASE TO PHASE METERS FEET

OVER 750 V TO 75 KV 3 10

OVER 75 KV TO 250 KV 4.5 15

OVER 250 KV TO 550 KV 6 20

12.3.4 Equipment Transit Clearances. A signal or flag person must guide cranes, cherry pickers, high lifts, and other equipment in transit near exposed energized lines or parts at all times. Do not move any equipment or machinery under energized overhead high-voltage lines or near exposed energized parts, unless clearances listed in table 12-2 are maintained. Unload and lower any boom or mast to transport position. Ground the equipment while it is being transported. Two grounds must be leap-frogged as the vehicle is moved or the vehicles must be treated as energized.

TABLE -2—EQUIPMENT IN TRANSIT CLEARANCES

UP TO 50 KV 4 FEET

50 KV TO 345 KV 10 FEET

OVER 345 KV UP TO 750 KV 16 FEET

TABLE 3—WORKING SPACES AROUND ENCLOSURES AND EQUIPMENT

Working spaces

Nominal voltage to ground Minimum clear distance (ft)

Condition 1 Condition 2 Condition 3

0 to 150 3 3 3

150 to 600 3 3.5 4

601 to 2500 3 4 5

2501 to 9000 4 5 6

9001 to 25000 5 6 6

Condition 1 - Exposed live parts on one side and no live parts or grounded parts on the other side of the working space, or exposed live parts on both sides effectively guarded by suitable wood or other insulating materials. Insulated wire or insulated bus bars operating at not over 300 volts to ground shall not be considered live parts. Condition 2 - Exposed live parts on one side and grounded parts on the other side. Consider concrete, brick, or tile walls grounded. Condition 3 - Exposed live parts on both sides of the work space (not guarded or enclosed, as provided in Condition 1) with the worker between.

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QUESTION 42:- PARAMETERS FOR DEFINING THE EXTENT OF HAZARDOUS AREAS AND ZONES? EXTENT OF HAZARDOUS AREA- GENERAL CONSIDERATIONS A complete knowledge of the physical properties of the flammable materials involved is essential for classifying a hazardous area. Properties and parameters of primary interest from an ignition standpoint are:

(a) Relative density (whether lighter or heavier than air) (b) Gas group (whether group II A, II B or II C)

(c) Flammable limits (d) Flash point (e) Volatility (f) Ignition temperature (g) Ignition energy (h) The level of ventilation (whether high, medium or low) (i)The rate of release Some of these characteristics have a direct influence on the degree and/or extent of hazardous areas while the others affect the design of electrical equipment. Some of the factors affecting the extent of hazardous zones and areas are as follows:

a) Where a gas or vapor is released into the atmosphere having a relative density less than one, the lighter vapor will rise in a comparatively still atmosphere. A vapour density greater than one, that is heavier than-air indicates the gas or vapor will tend to sink, and may thereby spread over some distance horizontally at a lower level. The latter effects will increase with compounds of greater relative vapor density.

b) The lower the “lower flammable limit” the larger may be the extent of the hazardous area.

c) A flammable atmosphere cannot exist if the flash point is significantly above the relevant maximum

temperature of the flammable liquid. The lower the flash point, the larger may be the extent of the hazardous area.

d) Ignition temperature and ignition energy of a flammable gas or vapour affect the design of electrical

apparatus for hazardous areas so that these do not present an ignition risk.

e) The extent of hazardous area may increase with increasing rate of release of flammable material.

f) With an increased rate of ventilation, the extent of hazardous area may be reduced. The extent may also be reduced by an improved arrangement of the ventilation system. The lower the degree of ventilation the higher the degree of zone and extent of area.

g) Whether Group II A, II B or II C. Group II A is lightly dangerous, Group II B is moderately dangerous and Group II C is highly dangerous and according to the group or degree of danger the extent may be increased.

(REFERENCE: - O I S D STD 113)

NOTE- Depending upon the above factors it is the duty of the production/process engineers and safety officers to decide the extent of hazardous areas and zones and electrical engineers are the first users to follow and implement the provisions with respect to installation of electrical equipments followed by instrumentation, mechanical and other officers. QUESTION 43:-WHAT ARE THE CABLES GENERALLY USED IN HYDRO-CARBON HAZARDOUS LOCATIONS?

The cables for mines and oil fields above low voltages shall be 1. Individually screened cables to prevent an internal short circuit there by preventing the cables from bursting 2. The metallic screening shall have continuity at all parts 3. And metallic screening shall have at least 50% conductivity of the largest conductor

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4. All armored cables in mines in mines should of copper conductor with double wire armor. Only double wire armor can prevent open sparking as a result of any fault far as practicable. 5. Single wire armored cables permitted in oil fields with permission rom DGMS as per CEA REGN 2010,106(d)

The following are some of the cables used in hydro-carbon hazardous areas. 1. E.P.R. cables (Ethylene Propylene Rubber) 2. X.L.P.E. cables (Cross Linked Poly Ethylene) 3. Silicon Rubber cables 4. L.D.P.E.cables (Low Density Poly Ethylene) 5. PTFE cables(Poly Tetra fluoro ethylene) 6. LSZH PVC cables(Low Smoke Zero Halogen PVC) 7. FEP cables(Fluorinated Ethylene Propylene) 8. Mineral Insulated Copper Clad (MICC) cables 9. PILCDWA(Paper Insulated Lead Covered Double Wired Armor)

Characteristics of cables for hydro carbon fields are; When selecting cables and conductors, only use those which can withstand the expected mechanical, chemical and thermal influences. Cables and conductors with thermoplastic sheath, duro plastic sheath, elastomer sheath or mineral insulation with metal sheath may be used for fixed routing. Cable branch lines must comply with the requirements for hazardous areas. The flame retardance of cables and conductors for fixed routing must be proven in accordance with IEC 603321 Isolate intrinsically safe and non‐ intrinsically safe circuits in cable bundles or ducts via insulation spacer or an earthed metal spacer (not required with screening or sheathing). NOTE: The most common sheath material for data cabling in use in the UK is PVC. For many environments, PVC is the ideal material, having superior mechanical characteristics and high reliability. However, in a fire, PVC emits heavy black smoke mixed with hydrochloric acid thus reducing vision immediately impairing breathing and additionally initiating hydrochloric acid, thus reducing vision, immediately impairing breathing, and additionally initiating corrosion of all equipment exposed to the fumes. For improved fire performance, it is common for LSZH Low Smoke Zero Halogen (usually meeting IEC61034, IEC60754‐ 2 and IEC60332‐ 3) cable sheaths to be used. (Cables meeting IEC60332‐ 3 have better fire performance characteristics than those meeting IEC60332‐ 1: They use either a thicker cable sheath or a more expensive sheath material and therefore the cable is more costly.) The armors may be either 1) SWA(Steel Wire Armor) or TCWA(Tinned Copper Wire Armor) 2)SWB(Steel Wire Braid) or TCWB(Tinned Copper Wire Braid0 3)STA(Steel Tape Armor) OR TCTA(Tinned Copper Tape Armor) CLASSIFICATION OS CABLES FOR FIRE APPLICATIONS Class A General flammability resistant IEC 60332-1 This cable provides a level of flammability r resistance for general purpose applications Class B Reduced flame spread IEC 60332-1& Provides reduced flame spread from the IEC 60332-3 bunched cables as required n cable risers Class C Low smoke and fume IEC 63001-1& This cable provides low emission of IEC 60754-1& smoke and corrosive fumes IEC 60754-2& IEC 61034 Class D Reduced fire hazard IEC 60332-1& Provides reduced flame spread with low IEC 60332-3& smoke and acid gas emission IEC 60754-1& IEC 61034

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Class E Limited fire hazard IEC 60332-1& Provides an overall limited fire hazard IEC 60332-3& performance and combines reduced IEC 60754-1& flame spread with low emission of IEC 60754-2& smoke and noxious fumes IEC 61034 Class F Fire resistant IEC 60331 Designed for wiring and inter connections Where it is required to maintain circuit Integrity under fire conditions for long Periods.

PROPERTIES OF

PTFE AND SOME

OTHER INSULATING MATERIALS

PTFE (Polytetrafluoroethylene) Teflon ® The combination of

chemical and physical properties of PTFE is a consequence of its true

fluorocarbon structure. This unusual structure leads to a material which has

an almost universal chemical inertness; complete insolubility in all known

solvents below 300°C; excellent thermal stability; and unsurpassed electrical

properties, including low dielectric loss, low dielectric constant and high

dielectric strength. Furthermore, PTFE does not brittle at very high or at very

low temperatures.

Corona Resistant PTFE is a corona resistant form of PTFE. It is a

homogeneous insulation having essentially all of the properties of pure PTFE,

but having approximately a thousand-fold longer high-voltage life. Corona

Resistant PTFE is unique among high voltage insulation in its excellent

resistance to electro-mechanical and chemical-mechanical stress cracking.

FEP (Fluorinated Ethylene Propylene) Teflon ®, life PTFE, has a fully

fluorinated structure which leads to excellent chemical, thermal, and electrical

properties. However, the high temperature limit for FEP is lower than PTFE,

approximately 200°C instead of 260°C. FEP has good melt-flow

characteristics which permit melt bonding to itself, to Kapton film, and to

PTFE

KAPTON ® Polyimide Film (Type H) is a polyimide film which

possesses a unique combination of properties among polymeric film

materials. The ability of Kapton to maintain its excellent physical, electrical,

and mechanical properties over a wide temperature range has opened new

design and application areas for wire and cable. A flame-resistant material,

Kapton polymide retains good strength above 500°C for a short time, and has

a zero strength temperature above 800°C. There is no known organic solvent

for the film and it is in-fusible and does not melt. Adhesives are available for

bonding Kapton polyimide to itself, to metals, and to other films. Kapton

(Type H) film is a laminate of polyimide and FEP which is heat-sealed to itself

above the FEP melt temperature. Application for Kapton film include wrapped

insulation for wire and cable, isolator over multi-core cables for high-

temperature jackets, and laminated insulation for flat cable.

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Polyurethane Extraordinary toughness and abrasion resistance are

characteristics of polyurethane. As a result, cable jackets can be made

considerably thinner than if more conventional jacketing materials were

used. In addition, polyurethane has good low temperature performance, good

weathering characteristics, and is resistant to oil, gasoline, and non-polar

solvents.

PVC (Poly Vinyl Chloride) A good balance of properties: electrical,

mechanical and thermal make PVC the choice material for cable jacketing

applications where size and weight are not critical.

Silicone Rubber This is a very soft insulation which has a temperature

range from -80°C to 200°C. It has excellent electrical properties plus ozone

resistance, low moisture absorption, weather resistance, and radiation

resistance. It typically has low mechanical strength and poor scuff

resistance.

QUESTION 44: FLP GLANDS FOR OIL AND GAS FIELDS?

Cable Gland Selection Criteria

Cable glands are a very important element in the protection of electrical equipment and should not be under estimated Testing Procedures for Cable Glands IP 66 Testing –100 liters of water for 3 minutes from 2.5 to 3 meters Continuity Testing of Armor- Gland is heated and cooled over time and resistivity should not change more than 10% Torque Test –Multiple spanners to prescribed tension with no damage on dis assembly Load Test -Unarmored cable gland with mandrel to not slip more than 6 mm over 6 hrs. Impact Test –I kg falling from 700cm (7 M) or 7 joules. No damage to gland Pressure Test Minimum of 450 psi without leakage for Ex „d‟, 2000 psi for UL2225 requirements CABLE GLANDS ARE OF TWO TYPES 1. Glands with sealing ring- For zone 1 hazardous areas with Group II A and B gases employing equipments or enclosures with less than 2 liters volume 2. Barrier type gland with compound sealing- For Group II C Gas Groups and/or enclosures having more than 2 liters volume.

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NOTE: It is important that the enclosure, cable gland and selection of cable- all should conform to the standards and codes. Any discrepancy in the selection of gland or cable may make the flame proofness less effective. QUESTION 45: MAINTENANCE OF FLP/EX-PROOF MOTORS? Repair procedures of the Ex motors are stated in IEC 79-19 standard. When it is not possible for repairs of Ex motors to be carried out at the manufacturer‟s plant, workshops assigned to this task must be accredited by the IEC Ex certifying body. At the time of repair: 1. Any repairs to any part of the Ex motor, must be done without any modification to the original motor design. 2. The electric connections must be tightened with correct torque to avoid resistance increases with consequent contact overheating. 3. The insulation air-distance and the surface-distance between conductors required by the standards must be respected. 4. All the screws, used to assemble the parts of the motors and of the terminal box, must be completely screwed home. 5. The replacement of seals and components for cable entrances must use spare parts supplied from the manufacturer in order to guarantee the original type of protection. 6. The Ex joint surfaces must not to be machined and any type of seal is not permitted on these joint surfaces. The joint surfaces must be clean & in order to avoid corrosion or water entrance, can be treated by means of a thin coat of silicon grease Post Repairs/After repairs In the case of full conformity of the motor to the original standard and certificate, it is requested to fix on the motor frame (without removing the original one) an additional nameplate, with the following data: - Mark R. (for Repair) - Name or code of the “repair shop”. - Number of the “repair operations”, performed by the repair shop. - Repair date. NOTE: In case of non conformity of the motor occurs after the repair operations: the original nameplate must be removed; the motor should no longer be considered suitable for use in hazardous areas, with explosion risk.

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Winding RTD‟s (Resistance Thermal Detectors) where fitted to the Stator Winding as Thermal Protection Devices. The RTD‟s are embedded in the head windings, RTD leads are terminated in an auxiliary box. The recommended temperature settings for safe operation of the motor are: ALARM SETTING 130° C TRIP SETTING 135° C Bearing RTD‟s where fitted to the motor as bearing temperature monitoring devices. These RTD‟s are fitted to the outer bearing caps, the connection wires are protected with a stainless steel wire tube and terminated inside an auxiliary box. The recommended bearing temperature limit settings are: ALARM SETTING 80° C TRIP SETTING 85° C Anti-condensate Heaters are installed in higher capacity motors to prevent moisture condensation in the motor during periods the motor is not running. They are fitted directly to the winding coils and are terminated to an auxiliary terminal box. They require to be connected to the power when motor is not powered. Heaters are 240V, 110W These anti-condensate heaters should not be kept on while the motor is running QUESTION 46: WHAT IS BREAK DOWN VOLTAGE? WHY EVEN INSULATORS FAIL AT BREAK DOWN VOLTAGE OR MORE? An electrical insulator is a material whose internal electric charges do not flow freely, and therefore make it very hard to conduct an electric current under the influence of an electric field Most insulators have a large band gap. There is always some voltage (called the break down voltage) that gives electrons enough energy to be excited into this band. Once this voltage is exceeded the material ceases being an insulator, and charge begins to pass through it. However, it is usually accompanied by physical or chemical changes that permanently degrade the material's insulating properties. QUESTION 47. GASSY SEAMS IN MINES DEFINITION? “Fiery seam” means a seam in which a fire or spontaneous heating exists in the working belowground or in open cast working lying within the precincts of a mine; “Gassy seam of the first degree” means coal seam or part thereof lying within the precincts of a mine not being an open cast working whether or not inflammable gas is actually detected in the general body of the air at any place in its working below ground, or

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when the percentage of the inflammable gas if and when detected, in such general body of air does not exceed 0.1 and the rate of emission of such gas does not exceed one cubic meter per ton of coal produced; “Gassy seam of the second degree” means coal seam or part thereof lying within the precincts of a mine not being an open cast working in which the percentage of inflammable gas in the general body of air at any place in the working of the seam is more than 0.1 or the rate of emission of inflammable gas per ton of coal produced exceeds one cubic meter but does not exceed ten cubic metres; “ Gassy seam of the third degree” means coal seam or part thereof lying within the precincts of a mine not being an open cast working in which the rate of emission of inflammable gas per ton of coal produced exceeds ten cubic metres; QUESTION 48- VFD AS A POWER SAVER VFD AS A POWER SAVING DEVICE VFD- Variable Frequency Drive- is a state of art frequency converter which converts fixed 400 volt, 50 hertz frequency supply to variable voltage (0 to 400 volt) and variable frequency (0 to 50 hertz) supply. The speed of a motor is given by N = 120 X F/ P Where N = Speed, F= Frequency and P = Poles Use of AC motors is more reliable and efficient comparative to using DC motors. Hitherto speed control of AC motors was not possible and since the advent of VFDs in recent years varying the AC motor speed is possible and replacing of AC motors in lieu of DC motors has become more common. Use of VFD makes near unity power factor and reactive power and losses are minimized. The most important is it saves power significantly. One of the statistics on world population of motors gives the following data

Use of 0.5 HP to 20 HP motors world-wide - 20%

Use of 20 HP to 200 HP motors world- wide - 60% to 65%

Use of 200 HP and more power motors - 15% to 20% If the consumers of category two use VFDs in their industries the power saving worldwide will be very high and power shortages and shut downs will be significantly reduced. How the VFD saves power? The pump affinity laws are

1. Flow is proportional to speed 2. Pressure (and torque) is proportional to square of the speed. 3. Energy is proportional to cube of the speed.

Suppose the motor speed is reduced 10%, the flow (from the pump connected to motor) will be reduced to 10% and the actual flow will be 90%.In decimals 90% is 0.9. And at the same time the pressure will be proportional to square of the speed that is 0.9 x 0.9 = 0.81 or 81% and the resultant pressure reduction is 19%

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In the same way the energy is proportional to the cube of the speed and 10% speed reduction or 90% speed will result in 0.9 x 0.9 x 0.9 = 0.729 or 72.9 % energy consumption. That is a saving of 27.1% energy. In the same way if the speed is reduced to 80%, the flow will be 80% and the pressure will be 0.64 or 64% resulting in a 36% pressure reduction and the power consumption is only 51.2% and the reduction in power is 48.8% The speed reduction or variable speed is obtained by the use of VFDs whose output voltages and frequencies are variable And the calculation will go on the same way for the speed reductions of 70%, 60% and so on Hence using VFD in industries for motors of 10 HP or more will significantly reduce power consumption and payback for the initial costs on VFDs can be realized in a reasonably short period The motors and connected pumps are mostly oversized or where variable speed requirements exist motors can be run through VFDs