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1 Indian regulations in Electrical Safety P.Lahiri BARC.

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Presentation on theme: "1 Indian regulations in Electrical Safety P.Lahiri BARC."— Presentation transcript:

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2 1 Indian regulations in Electrical Safety P.Lahiri BARC

3 2 Indian regulations. Indian Electricity Act Indian Electricity (Supply) Act Indian Electricity Regulatory Commission Act The Electricity Act –2003. Indian Electricity Rules Repealed under section 185 of Electricity act -2003

4 3 Make generation, transmission, distribution and utilization of electricity as safe as possible. Identification of different categories of agencies. Remove ambiguities from existing qualitative guidelines and pronounce precise quantitative technical requirement with respect to safety. Objectives of regulations

5 4 Categories of agencies Supplier of electricity. Consumer of electricity. Electrical inspector. Electrical contractor and supervisors. Authorized persons.

6 5 Hazards of electricity Electric shock:- Current flows through body or part of body when two surfaces having electrical potential difference is touched resulting in burn, disability or even death. Flashover:- Sudden collapse of electric field by having a conducting path between two electrical potential different surfaces resulting in burn, fire. Blast:- Failure of dielectric medium between two electrical potential different surfaces resulting in projectile, mechanical force, fire or burn. Heat:- Caused by loose connection in the circuit, overheating of insulation/ conductor due to overload or prolonged short circuit current etc. resulting in fire, burn.

7 6 Quantitative effect of electric current (up to 3sec.) on human (source Daziel) EffectmA d.ca.c 60Hz10kHz MFMFMF Perception threshold Shock but not painful Muscular control lost, breathing difficulty Ventricular fibrillation

8 7 Flash and flame burn Thermal burns, Current flows typically external, Damage to skin

9 8 Electric shock and flash burn

10 9 Occurrence of blast

11 10 Classification of rated voltage as per IE rule 250V 650V Low Voltage (LV) Medium Voltage (MV) High Voltage (HV) Extra High Voltage (EHV) 33kV Above 33kV

12 11 Authorization Avoid chaos Fixing up of responsibility Ensures expertise Authorization. Electrical isolation. Identification & display. Restriction of access. Inspection, testing etc. Preparedness for adversity. Other hazard precaution. Protection & interlocks. Clearances. Earthing. Reporting accidents.

13 12 Authorization rule RequirementApplicable forRule Work to be executed by licensed electrical contractor. All new, addition, alteration jobs having electrical scope except minor jobs. 45- (1), (3) Safety officer to be authorized by owner with approval of electrical inspector. Electrical installation with more than 250kW connected load 3, 4, 5, 6 Prior approval from electrical inspector to work Any electrical work on live apparatus/ line 36 (2)

14 13 Authorization cntd. Qualifications rule AgencyMinimum qualification Rule Authorized O & M person for generating station of capacity above 100MW and sub-stations of 132kV and above. Second class diploma in mechanical or electrical engineering & training from CEA approved institute. 3 (2A) Assistants to above ITI & training from CEA approved institute 3 (2A)

15 14 Electrical isolation. Quick de-energization Ensure de-energization while on work Authorization. Electrical isolation. Identification & display. Restriction of access. Inspection, testing etc. Preparedness for adversity. Other hazard precaution. Protection & interlocks. Clearances. Earthing. Reporting accidents.

16 15 Electrical isolation(Rule) Rating of service connectionIsolation device Rule CBSFU * LV, MV service connection  50- (b) (i) (ii) upto 1000kVA at 11kV  Above 1000kVA at 11kV  upto 2500kVA at 33kV  Above 2500kVA at 33kV  Any rating beyond 33kV 

17 16 LV,MV

18 17 11k,33k or

19 18 >33k

20 19 Electrical isolation device for transformers (Rule) Rating of transformerIsolation deviceRul e Pri:Sec: CBSFU * CBSFU * Upto 630kVA and primary side less than HV  50- (b) (i) (ii) upto 630kVA and primary side HV and above.  630kVA to 1000kVA irrespective of primary voltage  Above 1000kVA irrespective of primary voltage 

21 20 Above 1000kVA

22 21 Primary HV

23 22 630kVA

24 23 Identification & display Electricity is invisible:- –Various current carrying portions –Different circuits/ phases/ a.c/ d.c. etc. –Different voltages LV,HV,MV etc –Power flow directions. –ON/OFF positions and direction of operation of SFUs/CBs/Isolators. –Source locations of PCCs/ MCCs and load locations of each feeders of MCCs –Danger notices. Authorization. Electrical isolation. Identification & display. Restriction of access. Inspection, testing etc. Preparedness for adversity. Other hazard precaution. Protection & interlocks. Clearances. Earthing. Reporting accidents.

25 24 Identification & display (Rule) RequirementApplicable forRule Display of danger notice. Electrical installation rated MV and above. 35 Visual identification by distinct colour. All conductors connected to earthing system 32(1) Visual distinction of circuits, voltages, feeders etc. All electrical installation41

26 25 Restriction of access Thwart accidental or unauthorized access:- Authorization. Electrical isolation. Identification & display. Restriction of access. Inspection, testing etc. Preparedness for adversity. Other hazard precaution. Protection & interlocks. Clearances. Earthing. Reporting accidents.

27 26 Restriction of access (Rule) RequirementApplicable forRule Metallic covering which is electrically and mechanically continuous All live conductors for indoor installations. 51(1) (a) Metallic fencing of height not less than 1.8M. Out door sub-station.68(b)

28 27 Inspection testing & maintenance Ensure adequacy of safety related parameter: Maintaining safety related parameter within limit. Authorization. Electrical isolation. Identification & display. Restriction of access. Inspection, testing etc. Preparedness for adversity. Other hazard precaution. Protection & interlocks. Clearances. Earthing. Reporting accidents.

29 28 Commissioning inspection (Rule) Type of Installation Type of test (Rule do not specify) interpreted. Inspecting authority Any installation upto MV (not generating plant) Visual inspection. Insulation resistance. High voltage. Earth resistance. Any functional requirement. Supplier. Generating plant of capacity less than 10kW Same as aboveOwner

30 29 Commissioning inspection (Rule) cntd. Type of Installation Type of test (Rule do not specify) interpreted. Inspecting authority Generating plant of capacity more than 10kW Depending upon voltage level as desired by Electrical Inspector Electrical Inspector. HV or EHV installation Visual inspection, insulation resistance, high voltage, earth resistance, functional tests and test as desired by Electrical Inspector. Electrical Inspector.

31 30 Periodic inspection (Rule) Type of testMaximum time interval. Record keeping duration Test by inspector5 yearsNot specified Earth resistance for LV and MV installation 2 years2 years. Earth resistance for HV and EHV installation 1 year2 year Fire extinguishers1 yearNot specified

32 31 Preparedness. Mitigate the effect of fast acting electrical disaster Ensure correct course of action Authorization. Electrical isolation. Identification & display. Restriction of access. Inspection, testing etc. Preparedness for adversity. Other hazard precaution. Protection & interlocks. Clearances. Earthing. Reporting accidents.

33 32 Preparedness (Rule) EssentialApplicable forRule First-aid box, Restoration chart, Fire buckets Every generating station, enclosed sub-station and enclosed switch station 43(2), 44(1), 43(1) Two or more gas masks 1.Generating station with capacity of 5MW and above 2.Enclosed sub-station with transformation capacity of 5 MVA and above 43(3)

34 33 Preparedness (Rule) cntd. EssentialApplicable forRule Artificial respirator Every manned high voltage or extra-high voltage generating station, sub-station or switch station 44(4) Trained personnel for providing artificial respiration. All attended generating station and sub-station. 44(3)

35 34 Possibility of success of artificial respiration source Edition Electric Institute resuscitation manual

36 35 Other hazard precaution. Reduce potential initiating events of accident Authorization. Electrical isolation. Identification & display. Restriction of access. Inspection, testing etc. Preparedness for adversity. Other hazard precaution. Protection & interlocks. Clearances. Earthing. Reporting accidents.

37 36 Other hazard precaution.(Rule) SituationSafety measureRule Electrical installation in explosive atmosphere Explosion proof/ dust tight depending upon the hazardous zone as per IS (d) Multistoried building with height more than 15M. 1.Power cable ducts shall not be used for other services 2.Power cable ducts shall have fire barrier at each floor crossing 50A- (4)

38 37 Other hazard precaution.(Rule) cntd.. SituationSafety measureRule Electrical installation with more than 2000litres of oil 1.Baffle wall of 4hr fire rating between single phase banks and on consumer premise. 2.Oil soak pit for full quantity of oil 64(2) -(e) Electrical installation with more than 9000litres of oil 1.Measures mentioned above. 2.Fire extinguisher. 3.Oil draining arrangement. 64- (2)(e)

39 38 Other hazard precaution.(Rule) cntd.. SituationSafety measureRule Substation and switch station in the basement 1.Entrance shall have 2hr fire rating fire resistance door 2.A curb at entrance to trap oil flow. 3.Direct access to transformer from outside 4.Transformer protection by automatic HVWSp/ CO 2 / BCF/ BTM/ N 2 injection and drain. 64- (2) (f)- (ii)

40 39 Other hazard precaution.(Rule) cntd.. Location based on oil inventory Total oil quantity in litre ( includes transformer and other apparatus ) LocationRule IndoorOut- door Indl: buildingRes:/ com: bldg. Any floor of 1 st Bs. Gr. Fl. Other floors No oil.  64 (2) 2000 or less  2000 to 9000  9000 or more 

41 40 Protection & interlocks. Avoid human errors Authorization. Electrical isolation. Identification & display. Restriction of access. Inspection, testing etc. Preparedness for adversity. Other hazard precaution. Protection & interlocks. Clearances. Earthing. Reporting accidents.

42 41 Transformer protection RatingMandatory relay protection Remark Less than 630kVA and primary side less than HV No relay based protection is mandatory Not specified Less than 630kVA and primary side more than HV Over current/ short circuit relay etc for secondary CB. Not specified but implied by R50(b)(ii) 630kVA to 1000kVA Over current/ short circuit relay etc for secondary CB. Not specified but implied by R50(b)(ii)

43 42 Transformer protection cntd.. RatingMandatory relay protection Remark 1000kVA to 10MVA1.Bucholz 2.Winding temp: 3.Oil temp: R64(2) More than 10MVA1.Bucholz 2.Winding temp: 3.Oil temp: 4.Differential R64(2)

44 43 HV & EHV installations interlocks SituationPreventive interlockRule Isolator and CB in series Isolator operation not allowed when CB is closed. 64 (A) (1) Earthing switch and isolator Earthing switch can not be closed when isolator is closed Two or more incomer feeders to a bus bar but not intended for parallel operation Only one feeder can be switched on at a time

45 44 HV & EHV installations interlocks cntd.. SituationPreventive interlockRule Two or more transformers in parallel Secondary CB trips if primary of that transformer trips. 64 (A) (1) Doors or gates give access to live parts Doors can not be opened when any part is live. Neutral switching device between neutral and earthing is used for generator GCB can not be closed when neutral breaker is open.

46 45 HV & EHV installations protection Protection against. Type of relayMandatory forRule Over current.Over current/ short circuit relay. Any Equip., cable supply line etc. 64A (2) Rising touch potential. Earth leakage/ earth fault. Generator rated over 100kVA Internal fault.Differential relayGenerator rated over 1MVA Bus bars rated over 200kV Switching over voltage/ lightning Lightning arrestorOverhead line terminations 92(1)

47 46 Other protections Protection for. Type of relayMandatory forRule Human safety. ELCB/ RCCB/ etc. Any installation having connected load more than 5kW at MV or above 61A DC earthing.Over current relay between earthed middle conductor and earth. DC three wire system 61 (1) (d) (i)

48 47 mSec 50H a.c current (rms mA) Zone 1- Usually no reaction,Zone 2 – Reaction may occur but usually no patho- psychological dangerous effect, Zone 3- No risk of fibrillation, Zone 4- Fibrillation possible (50% probability), Zone 5- Unsafe or fibrillation Time/ Current for a.c 50Hz

49 48 Clearances (physical spacing) Minimum air insulation clearance. Minimum space to work. Minimum space for escape. Authorization. Electrical isolation. Identification & display. Restriction of access. Inspection, testing etc. Preparedness for adversity. Other hazard precaution. Protection & interlocks. Clearances. Earthing. Reporting accidents.

50 49 Clearances for bare conductor other than overhead lines(Rule) VoltageSection clearance (outdoor) in m.m. Ground clearance (outdoor) in m.m Rule Upto 11kV kV kV kV kV

51 50 Clearance above ground of overhead lines across/ along a street (Rule) ConditionSystem voltageClearance in mm Rule Across LV, MV HV6100 Along LV, MV5500 HV5800 Any where else LV, MV, HV (upto11kV) 4600 HV(above 11kV)5200 Every whereEHV for every 33kV but not less than 6100

52 51 Clearance of overhead lines from building(Rule) ConditionSystem voltageMinimum clearance in mm Vertical (IE R 79) LV, MV2500 HV3700 EHV for every 33kV Horizontal (IE R 80) LV, MV1200 HV upto 11kV1200 HV above 11kV 2000 EHV for every 33kV

53 52 Section clearance SC

54 53 GC GROUND CLEARANCE GROUND LEVEL Ground clearance Height of tall man’s raised finger tip with raised hand- 2.5m

55 54 Earthing system. Limit touch potential Limit step potential Safe predefined passage for fault current Facilitate detection of incipient fault Reduce neutral shifting Authorization. Electrical isolation. Identification & display. Restriction of access. Inspection, testing etc. Preparedness for adversity. Other hazard precaution. Protection & interlocks. Clearances. Earthing. Reporting accidents.

56 F E Et E/X CURVE Es Earth Mat X 1M 0.5M Step & Touch potential

57 56 Earthing (Rule) RequirementApplicable forRule Earthing terminal by Supplier. LV consumer33 Separate earthing terminal by supplier and consumer. MV and above33 Minimum two independent and redundant path with two earth electrode. Earthing network for equipment, system. R61(2), R61(3), R51(1)(b), R67(1) All metallic part not intended to serve as conductor shall be earthed. All electrical apparatus Grounding of neutral.a.c electrical power supply system more than 125V 61(1)(a), 64(3)

58 57 Reporting of accidents Reporting for analysis. Fast reporting prevents suppression of facts. Authorization. Electrical isolation. Identification & display. Restriction of access. Inspection, testing etc. Preparedness for adversity. Other hazard precaution. Protection & interlocks. Clearances. Earthing. Reporting accidents.

59 58 Reporting of accidents (Rule) Type of accidentReport format Maximum period for reporting Rule Fatal involving loss or injury Telegraphic and 24hours 44A Written48hours Failure of transformer or reactor above 20MVA Written48hours65(8)

60 59 Conclusion Regulations can induce more concern. Regulations can not rule out accidents by themselves Every concerned individuals should handle electricity in safe manner Do not try to find out loopholes of regulation to limit our responsibility. Try to adopt a proactive approach by understanding the intentions of the regulation authors. In case of doubt ask electrical inspector or Central Electricity Authority.

61 60

62 61 Clearance across the road

63 62 Clearance along the road

64 63 Clearance anywhere else

65 64 Clearance from building Vertical clearance Horizontal clearance

66 65 Fl-1 Fl-4 Fl-2 Electrical service shaft Fire barrier Cables Fire barrier in cable duct

67 66 Ground clearance for bare conductor other than overhead lines(Rule) VoltageClearance in mm Outdoor Upto 11kV kV kV kV kV8000 Height of tall man’s raised finger tip with raised hand- 2.5m

68 67 Phase to Phase(Rule) VoltageClearance in mm Outdoor Ph~PhPh~ESec:Ground 11kV460 33kV915 66kV kV kV4000

69 68 Phase to earth(Rule) VoltageClearance in mm Outdoor 11kV305 33kV610 66kV kV kV3500

70 69 Clearances It denotes the minimum distance in air between two potentially different points (this includes earthed/ ground surfaces) to avoid flashover during normal and transient over voltage. Phase to earth Minimum distance between live conducting parts and neighboring earthed parts. Phase to earth

71 70 Clearances It denotes the minimum distance in air between two potentially different points (this includes earthed/ ground surfaces) to avoid flashover during normal and transient over voltage. Phase to earthPhase to Phase Minimum distance between live parts of different phases. Phase to phase

72 71 Clearances It denotes the minimum distance in air between two potentially different points (this includes earthed/ ground surfaces) to avoid flashover during normal and transient over voltage. Phase to earth Phase to Phase Isolating clearance Minimum distance between two sides of an open isolator Isolating clearance

73 72 Clearances It denotes the minimum distance in air between two potentially different points (this includes earthed/ ground surfaces) to avoid flashover during normal and transient over voltage. Section clearance Minimum distance between maintenance zone and nearest live part plus one stretched arm length of a person Phase to earth Phase to Phase Isolating clearance Section clearance

74 73 Clearances It denotes the minimum distance in air between two potentially different points (this includes earthed/ ground surfaces) to avoid flashover during normal and transient over voltage. Ground clearance Minimum distance between lowest point of support insulator and ground Phase to earth Phase to Phase Isolating clearance Section clearance Ground clearance

75 74 CLEARANCES IN OUTDOOR PH-TO PH STRUCTURE PHASE TO EARTH GANTRY TOWER Phase to earth & phase to phase clearance P-E ruleP-P rule

76 75 Isolating clearance

77 76

78 77 Safety provisions in IE Rules Authorization. Electrical isolation. Identification & display. Restriction of access. Inspection, testing etc. Preparedness for adversity. Other hazard precaution. Protection & interlocks. Clearances. Earthing. Reporting accidents.

79 78


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