CABLEFIRE.ppt

7/23/2019 CABLEFIRE.ppt

http://slidepdf.com/reader/full/cablefireppt 1/20

PREVENTION &

RESTRICTION OF

FIRE DUE TO

CABLES

PRESENTED BY:

ATUL SHRIVASTAVA & SANJAY SETH

PROJECT ENGINEERING (ELECT.), NTPC



CAUSES OF CABLE FIRES

• External sources like oil, rubbish, welding in the vicinity of

electrical cables.

• Electrical overloads.

• Loose connections & sparking.• Any other external source.

• Short ircuits.

ables are seldo! the cause of a fire unless they are da!aged.



EFFECTS OF CABLE FIRES

"he cable fires produce large #uantity of

dense & toxic s!oke which reduces

visibility. "his !akes escape & firefighting operation very difficult. "his fire

causes heavy da!ages to the e#uip!ent

because of s!oke, heat and generation

of $ydrochloric acid fro! cables which is

highly corrosive. "his also generally

causes loss of generation.



PROPERTIES OF CABLE OUTER SHEATH

• %xygen index the !ini!u! percentage of oxygen in a

!ixture of oxygen and nitrogen which will sustain

co!bustion. 'f this is less than the proportion of oxygen in

the at!osphere ()*+, the !aterial will burn freely in air.• Self-ignition te!perature the te!perature at which it will

start to ignite.

• $L e!ission the percentage by weight of hydrochloric

acid gas e!itted during co!bustion.• S!oke e!ission the density of the s!oke e!itted after

specified ti!es of subection to a standardised fla!e in a

standardised test cell.



COMPARATIVE PROPERTIES OF FRLS PVC

CABLES AGAINST ORDINARY PVC CABLES

PVC Cables FRLS Cables

/ %xygen 'ndex as per AS"01 )234 Less than )4 5reater than )6

/ S!oke density as per AS"01 )274 5reater than 28+ Less than 98+

/ Acid gas generation as per 'E-:97-' 5reater than 48+ Less than )8+

/ ;la!!ability test as per 'EEE 424 does not !eet <ass the test

/ "est under fire conditions 'E44)-4 does not !eet <ass the test

(ategory-=



REDUCING THE LOSS OF GENERATION

BY SUITABLE CABLING PHILOSOPHY

• "he use of co!!on cable vaults for different units !ay lead to outage of all the units

in case of fire in the cable vault. "hus the provision of seperated cable vaults

unitwise is preferred.

• All cables associated with a unit shall be segregated fro! cables of other units.

ables associated with unit switchgear bus >A> shall be segregated fro! those

associated with unit switchgear bus >=>. Si!ilarly cables for station switchgear bus

A&= shall also be segregated.

• <ower and control cables for A drives and corresponding e!ergency A or 1

drives shall be laid in a segregated route.• "wo separate cable routes one on each side shall be provided for each boiler unit.

ables for one set of auxiliaries such as '1, ;1, <A fan & half of the coal !ills, shall

be routed in one route & for other set of auxiliaries through other route.

?.%@"'@E1 ...



REDUCING THE LOSS OF GENERATION

BY SUITABLE CABLING PHILOSOPHY

• ;or inter plant cabling of station auxiliaries such as 10 plant, Air co!pressor,

Ash handling & coal handling etc. !ini!u! two segregated cable routes shall

be provided such that in a single incident-

/ @ot !ore than half the pu!ps are lost in a station in case of B pu!ps.

/ All the strea!s are not lost in case of 10 plant, co!pressor house etc.

/ =oth the strea!s of conveyors are not lost in case of coal and ash handling.

/ @ot !ore than half the ash slurry series are lost in a station.

'f segregation is not practicable, separation !ay be adopted with barrier

under special circu!stances.



COMMON PRACTICES FOR

USE OF CABLE FIRE SEALING UK Practice * hour rated fire barriers and penetration seals at following

locations are generally adopted !eeting following basic

considerations.

Atleast one barrier within an enclosed route between any two

points of access andCor exit.

;or long narrow enclosed routes, barriers to be located at an

interval of 98!.

;or cable shaftsCrisers, horiDontal barriers to be locatedcoinciding with external solid floors.

Bhere cables pass through barriers or enclosures are to be

sealed by fireCs!oke !aterial.




USE OF CABLE FIRE SEALING Russia !ractice

/ 8.:9 hours rated fire rating, fire penetrationsCbarriers are

adopted.

/ ;or the wall crossings the conduits are e!bedded in glass

wool and !ortar !ixtures and then the gaps between cables

and conduits are sealed by asbestos and glass wool pads.

/ ;or floor opening i.e. shaftsCrisersCbelow enclosures, theye!bed conduits in concrete floor and seal the re!aining

portion of cables and conduits by waterCfire proof !aterials.




USE OF CABLE FIRE SEALING A"erica Practice

/ %pening beneath e#uip!ent shall be closed with 1oworning 4-3972 silicon "F foa!, Gohns 0anville

"ype *84 cera for! board.

/ Bherever the cables pass through wall, the wall

opening shall be sealed with penetration fire seals.

"he fire rating of the seal syste! shall have atleast

the sa!e rating as that of the wall.



Cable Fire Sealing Practices

followed in NTPC 'n @"< two types of fire sealing !aterial are

being used / "ype HAI & "ype H=I.

T#!e $A% / "his is used for sealing of floor opening

below &' panels, control panels, = etc. in E &

. "hese are sealed with either 1ow corning silicon"F foa! or e#uivalent foa! syste! or suitable 0"

syste! using individual poly!er blocks for each cable

along with suitable fra!e work.




followed in NTPC T#!e $B% / "his is used for sealing of floor openings below

$"CL" Switchgear, distribution boards, wall & floor crossings

of cablesCcable trays in !ain plant area. "hese are to be

sealed with 1ow orning Silicon "F foa! or e#uivalentfoa! syste! or suitable 0" syste! using individual

poly!er blocks for each cable along with suitable fra!e work

or any other e#uivalent proven fire sealing syste!.

/ "hus fire sealing !aterial for type HAI shall be either foa! type

or 0" blocks. $owever type H=I !aterial can be foa! type,

0" blocks, 0ineral wool, !ortar syste! or any other proven

syste!.



VARIOUS TYPES OF FIRE SEAL SYSTEMS

• Silico Bloc!"

• Silico #o$% S$li' S"%

• *o+$+ S$li' S"%

• Roc!ool S$l S"%

• C$-l Co$i' S"%



SILICON BLOCKS FIRE SEAL SYSTEM

'n this syste! silicon blocks along with a

fra!e are used for fire sealing. As this

syste! is expensive, it is !ore appropriatewhere a large nu!ber of cables are involved

like below &' panels or =. "his syste!

provides a strong hold of cables and hence

gives better & neater dressing of cables. "hecables can be added or deleted in this

syste! at any stage ust by changing hollow

blocks with du!!y blocks or vice versa.



SILICON FOAM SEALING SYSTEM

"he silicon foa! sealing is for!ed by !ixing of

two !ediu! density li#uids supplied as A & =.

"he A & = co!ponents are thoroughly !ixed ina ** ratio, the product expands and cure to a

foa!ed elasto!er at roo! te!perature in one

to five !inutes. ost wise this syste! is

co!parable with silicon block syste!.



MORTAR SEALING SYSTEM

T %o+$+ "$l ""% i" l"" /0"i1 $"

co%0$+2 o Silico -loc! $2 Silico 3o$%

"$li' ""%". A" i" ""% i" l""/0"i1, i c$ - 33ci1l 4"2 3o+

o0i'" -lo HT & LT Sic'$+ & o+

$ll & 3loo+ o0i'". Ti" ""% i" 0"ic$ll, c%ic$ll, +%$ll "$-l $2 i"

%c$ic$ll +o-4".



ROCKWOOL SEAL SYSTEM

'n this syste! rockwool noodles or rockwool

slabs are used to seal the cable openings. "he

encasing panel is used to retain the rockwoolslabs. "his syste! can be effectively used for

openings below $" & L" Switchgear & other

wall & floor openings. "his syste! is cost wise

co!parable with 0ortar Sealing & able

coating syste!.



CABLE COATING SYSTEM

"he fire resistant cable coating can be either used for cable fire

sealing alongwith partition boards or can be applied on cables

where risk of fire is !ore. 'n the first type, coating on cables

on either sides of partitions and !ineral boards are re#uired."his syste! can be used for wall and floor pentration. ost

wise this syste! is co!parable with 0ortar seal & ockwool

seal syste!.

'n the second type, coating is applied on cables where there isno opening but the risk of fire is high. 'n areas like vicinity of

coal !ills, where risk of fire is considerably higher because of

high concentration of coal dust, cable coating !ay be applied.



THANK YOU




followed in NTPC Area Detection System Protection System

able vaults and spreader a 'onisation type s!oke 0ediu! velocity spray

roo! in !ain plant bldg., detectorJ syste!

ES<,$< & Swyd areas. b <hotoelectric type

s!oke detector J c Linear cable sensor

(1igital

ontrol roo!, control e#uip!ent a 'onisation type s!oke a 'nert gas

roo!, invertor roo! & 1AS roo! detectorJ

b <hotoelectric type b <ortable fire

s!oke detectorJ extinguishers

$< control roo!, switchyard 'onisation type s!oke <ortable fireontrol roo!, ES< ontrol detectorsJ extinguishers

oo!.

Switchgear roo!s located 'onisation type s!oke <ortable fire

'nside power house bldg. detectorsJ extinguishers

J Analog addressable intelligent type

CABLEFIRE.ppt

Documents

Transcript of CABLEFIRE.ppt