design bus bar

8/19/2019 Design Bus Bar

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DESIGN OF BUS BARSBus bars are Cu/Al rods of thin walled tubes and operate at onstant !olta"e# $he bus%bars are desi"nedto arr& nor'al urrent ontinuousl&# $he ross setion of ondutors is desi"ned on the basis of rated nor'alurrent and the followin" fators( S&ste' !olta"e) position of sub%station# Fle*ibilit&) reliabilit&of suppl& andost#Our desi"n 'ust ensure eas& and uninterrupted 'aintenane) a!oidin" an& dan"er to the operatin" ofoperatin" personnel# It 'ust be si'ple in desi"n and 'ust possess pro!ision for future e*tension# An&flutuation of load 'ust not hinder its 'ehanial haraters# $he sub%station bus bars are broadl& lassified inthe followin" three ate"ories(+#,

Outdoor ri"id tubular bus%bars#+#-Outdoor fle*ible ACSR or Al allo& bus%bars#+#.Indoor bus bars#In our substation) we ha!e hosen ONE AIN BUS AND ONE $RANSFER BUS s&ste'# $he buses areoupled usin" a bus%

oupler whih failitates load transfer while 'aintenane and fault onditions#0oad atered 1 233 45olta"e 1 +,2 65Rated urrent is ta7en to be I a'pere) we "et8 1 9, 5I os :4e ta7e power fator as 3#;1 ;<+#;< a'pereGoin" b& the rated urrent that is re=uired to be atered and 7eepin" in 'ind the future pro!ision ofload we hose twin 'oose ondutor for the purpose of 'ain bus and nor'al sin"le 'oose and nor'al 'oosefor transfer bus

t&pes of bus bar s&ste'

$here are 'an& different eletrial bus s&ste' she'es a!ailable but seletion of a partiular she'edepends upon the s&ste' !olta"e) position of substation in eletrial power s&ste') fle*ibilit& needed ins&ste' and ost to be e*pensed#

http://www.electrical4u.com/electrical-power-substation-engineering-and-layout/

http://www.electrical4u.com/electric-power-single-and-three-phase/

http://www.electrical4u.com/electric-power-single-and-three-phase/




The Main Criteria’s To be Considered During Selection of one Particular Bus – Bar ArrangementScheme Among Others

>i? Si'pliit& of s&ste'# >ii? Eas& 'aintenane of different e=uip'ents# >iii? ini'i@in" the outa"e durin"

'aintenane# >i!? Future pro!ision of e*tension with "rowth of de'and# >!? Opti'i@in" the seletion of busbar arran"e'ent she'e so that it "i!es 'a*i'u' return fro' the s&ste'# So'e !er& o''onl& usedbus bar arran"e'ent are disussed below%

Single Bus System

Sin"le Bus S&ste' is si'plest and heapest one# In this she'e all the feeders and transfor'er ba& areonneted to onl& one sin"le bus as show#

Advantages of Single Bus System

+? $his is !er& si'ple in desi"n# 2? $his is !er& ost effeti!e she'e# ,? $his is !er& on!enient tooperate#

Disadvantages of Single Bus System

+? One but 'aor diffiult& of these t&pe ofarran"e'ent is that) 'aintenane of e=uip'ent of an& ba& annot be possible without interruptin" the

feeder or transfor'er onneted to that ba&# 2? $he indoor ++65 swithboards ha!e =uite often sin"le busbar arran"e'ent#

Single Bus System ith Bus Sectionali!er

So'e ad!anta"es are reali@ed if a sin"le bus bar is setionali@ed with iruit brea7er# If there are 'orethan one ino'in" and the ino'in" soures and out"oin" feeders are e!enl& distributed on the setionsas shown in the fi"ure) interruption of s&ste' an be redued to a "ood e*tent#



Advantages of Single Bus System ith Bus Sectionali!er

If an& of the soures is out of s&ste') still all loads an be fed b& swithin" on the setional iruit brea7er or bus oupler brea7er# If one setion of the bus bar s&ste' is under 'aintenane) part load of thesubstation an be fed b& ener"i@in" the other setion of bus bar#

Disadvantages of Single Bus System ith Bus Sectionali!er

+? As in the ase of sin"le bus s&ste') 'aintenane of e=uip'ent of an& ba& annot be possible withoutinterruptin" the feeder or transfor'er onneted to that ba&# 2? $he use of isolator for bus setionali@in"does not fulfill the purpose# $he isolators ha!e to be operated off iruit and whih is not possible withouttotal interruption of bus bar# So in!est'ent for bus%oupler brea7er is re=uired#

Double Bus System

+? In double bus bar s&ste' two idential bus bars are used in suh a wa& that an& out"oin" or ino'in"feeder an be ta7en fro' an& of the bus# 2?Atuall& e!er& feeder is onneted to both of the buses inparallel throu"h indi!idual isolator as shown in the fi"ure#

http://www.electrical4u.com/electrical-circuit-breaker-operation-and-types-of-circuit-breaker/


http://www.electrical4u.com/electrical-isolator-or-electrical-isolation-switch/






B& losin" an& of the isolators one an put thefeeder to assoiated bus# Both of the buses are ener"i@ed and total feeders are di!ided into two "roups)

one "roup is fed fro' one bus and other fro' other bus# But an& feeder at an& ti'e an be transferredfro' one bus to other# $here is one bus oupler brea7er whih should be 7ept lose durin" bus transferoperation# For transfer operation) one should first lose the bus oupler iruit brea7er then lose theisolator assoiated with the bus to where the feeder would be transferred and then open the isolatorassoiated with the bus fro' where feeder is transferred# 0astl& after this transfer operation he or sheshould open the bus oupler brea7er#

Advantages of Double Bus System

Double Bus Bar Arran"e'ent inreases the fle*ibilit& of s&ste'#

Disadvantages of Double Bus System

$he arran"e'ent does not per'it brea7er 'aintenane with out interruption#

Double Brea"er Bus System

In double brea7er bus bar s&ste' two idential bus bars are used in suh a wa& that an& out"oin" orino'in" feeder an be ta7en fro' an& of the bus si'ilar to double bus bar s&ste'# Onl& differene is thathere e!er& feeder is onneted to both of the buses in parallel throu"h indi!idual brea7er instead onl&isolator as shown in the fi"ure# B& losin" an& of the brea7ers and its assoiated isolators) one an putthe feeder to respeti!e bus# Both of the buses are ener"i@ed and total feeders are di!ided into two"roups) one "roup is fed fro' one bus and other fro' other bus si'ilar to pre!ious ase# But an& feederat an& ti'e an be transferred fro' one bus to other# $here is no need of bus oupler as beause theoperation is done b& brea7ers instead of isolator# For transfer operation) one should first lose the

isolators and then the brea7er assoiated with the bus to where the feeder would be transferred and then











he or she opens the brea7er and then isolators assoiated with the bus fro' where feeder is transferred#

One and A #alf Brea"er Bus System

$his is an i'pro!e'ent on the double brea7er she'e to effet sa!in" in the nu'ber of iruit brea7ers#For e!er& two iruits onl& one spare brea7er is pro!ided# $he protetion is howe!er o'pliated sine it'ust assoiate the entral brea7er with the feeder whose own brea7er is ta7en out for 'aintenane# Forthe reasons "i!en under double brea7er she'e and beause of the prohibitor& osts of e=uip'ent e!enthis she'e is not 'uh popular# As shown in the fi"ure that it is a si'ple desi"n) two feeders are fedfro' two different buses throu"h their assoiated brea7ers and these two feeders are oupled b& a thirdbrea7er whih is alled tie brea7er# Nor'all& all the three brea7ers are losed and power is fed to both theiruits fro' two buses whih are operated in parallel# $he tie brea7er ats as oupler for the two feederiruits#

Durin" failure of an& feeder brea7er) the power is fed throu"h the brea7er of the seond feeder and tiebrea7er) therefore eah feeder brea7er has to be rated to feed both the feeders) oupled b& tie brea7er#





Advantages of One and A #alf Brea"er Bus System

Durin" an& fault on an& one of the buses) that fault& bus will be leared instantl& without interruptin" an&feeders in the s&ste' sine all feeders will ontinue to feed fro' other health& bus#

Disadvantages of One and A #alf Brea"er Bus System

$his she'e is 'uh e*pensi!e due to in!est'ent for third brea7er#

Main and Transfer Bus System

$his is an alternati!e of double bus s&ste'#$he 'ain oneption of ain and $ransfer Bus S&ste' is) here e!er& feeder line is diretl& onnetedthrou"h an isolator to a seond bus alled transfer bus# $he said isolator in between transfer bus and

feeder line is "enerall& alled b&pass isolator# $he 'ain bus is as usual onneted to eah feeder throu"ha ba& onsists of iruit brea7er and assoiated isolators at both side of the brea7er# $here is one busoupler ba& whih ouples transfer bus and 'ain bus throu"h a iruit brea7er and assoiated isolators atboth sides of the brea7er# If neessar& the transfer bus an be ener"i@ed b& 'ain bus power b& losin"the transfer bus oupler isolators and then brea7er# $hen the power in transfer bus an diretl& be fed tothe feeder line b& losin" the b&pass isolator# If the 'ain iruit brea7er assoiated with feeder is swithedoff or isolated fro' s&ste') the feeder an still be fed in this wa& b& transferrin" it to transfer bus#

Sitching O$eration for Transferring a %eeder to Transfer Bus from Main Bus ithout &nterru$tionof Poer

>i? First lose the isolators at both side of the bus oupler brea7er#

>ii? $hen lose the b&pass isolator of the feeder whih is to be transferred to transfer bus#

>iii? Now ener"i@ed the transfer bus b& losin" the bus oupler iruit brea7er fro' re'ote#

>i!? After bus oupler brea7er is losed) now the power fro' 'ain bus flows to the feeder line throu"h its'ain brea7er as well as bus oupler brea7er !ia transfer bus#













>!? Now if 'ain brea7er of the feeder is swithed off) total power flow will instantaneousl& shift to the busoupler brea7er and hene this brea7er will ser!e the purpose of protetion for the feeder#

>!i? At last the operatin" personnel open the isolators at both sides of the 'ain iruit brea7er to 'a7e itisolated fro' rest of the li!e s&ste'# So it an be onluded that in ain $ransfer Bus S&ste' the'aintenane of iruit brea7er is possible without an& interruption of power# Beause of this ad!anta"e

the she'e is !er& popular for ,,65 and +,65 s&ste'#

Double Bus System ith By$ass &solators

$his is o'bination of the double bus s&ste'and 'ain and transfer bus s&ste'# In Double Bus S&ste' with B&pass Isolators either bus an at as'ain bus and seond bus as transfer bus# It per'its brea7er 'aintenane without interruption of powerwhih is not possible in double bus s&ste' but it pro!ides all the ad!anta"es of double bus s&ste'# It

howe!er re=uires one additional isolator >b&pass isolator? for eah feeder iruit and introdues sli"hto'pliation in s&ste' la&out# Still this she'e is best for opti'u' eono'& of s&ste' and it is bestopti'u' hoie for 22365 s&ste'#

'ing Bus System

$he she'ati dia"ra' of the s&ste' is "i!en in the fi"ure# It pro!ides a double feed to eah feederiruit) openin" one brea7er under 'aintenane or otherwise does not affet suppl& to an& feeder# Butthis s&ste' has two 'aor disad!anta"es# One as it is losed iruit s&ste' it is ne*t to i'possible toe*tend in future and hene it is unsuitable for de!elopin" s&ste'# Seondl&) durin" 'aintenane or an&other reason if an& one of the iruit brea7er in rin" loop is swith of reliabilit& of s&ste' beo'es !er&poor as beause losed loop beo'es opened# Sine) at that 'o'ent for an& trippin" of an& brea7er in

the open loop auses interruption in all the feeders between tripped brea7er and open end of the loop#









design bus bar

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