Write-up CT

8/13/2019 Write-up CT

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CGL WRITE UP ON FEATURES OF OUR LIVE TANK TYPE CTs'

* The offered CTs shall confirm to IS: 2705 (1992), and the insulatin !il shall confirm to there"uirement of IS: ##5 (199#)$

* %e are usin hollo& 'orcelain insulator conformin to IS: 521 (190) in our "ui'ments$

+ae of 'orcelain shall -e IC . +odern . %SI . / . dit3a /irla . C4I hur6a . alian(China)$

* The offered CT shall -e of li8e tan desin$ ollo&in are the distinct ad8antae

a) iid and short 'rimar3 conductor &ith onl3 &elded 6oints i8es hih short circuitcurrent &ithstandin ca'a-ilit3 and relia-ilit3$

-) ;rimar3 &indin -ein short and uniforml3 distri-uted around Core, CT is trul3 lo&reactance t3'e, &hich has inherent -etter transient 'erformance$

c) Since the ma6or insulation is not o8er the hih current carr3in 'rimar3, &hich is themain source of heat (as in the case of ead tan t3'e desin$) the insulation doesnot et heated u' &hile dissi'atin the heat enerated$ This facil itates much su'eriorthermal sta-ilit3 of insulation and loner life$

* The CT offered -3 us is trul3 hermaticall3 sealed unit$ %e are 'ro8idin stainless steel -ello&instead of inert as cushion to tae care of 8olumetric ein$

* To' housin, flanes for 'orcelain insulators and the -ottom housin su''ort shall -e ofaluminium allo3 &ith e corrosi8e 'ro'ert3, hence 'aintin is not re"uired$ Thesecondar3 terminal -o< shall -e Steel fa-ricated and hot di' ala8ani=ed$

* ;rimar3 Terminal &ill -e also of aluminium

* In our CT, on the -ottom su''ort earthin holes are 'ro8ided, the earth>mat can -e directl3-olted to this holes and so se'arate earthin terminals. connectors are not re"uired

* rcin horns.nd shield.corona shield.?radin rins are not re"uired for the CT offered -3

us$

* ll hard&are &ill -e electroal8anised$


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* CT 'erformance is uaranteed for fre"uenc3 8ariation of @#A, ho&e8er no test shall -ecarried out to su-stantiate the same as no such test is s'ecified in IS: 2705 (1992)$

* or the offered e"ui'ments, &e do not recommend an3 s'ares$

* or offered e"ui'ments s'ecial and maintenance tools are not re"uired$


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DESIGN ASPECT OF CURRENT TRANSFORMERS WITH ALUMINIUM PRIMARY

1$0 luminium or Co''er is -ein used &orld>&ide for desin of 'rimar3 &indins &hich are inser8ice for man3 3ears includin India$

2$0 IS: 2705 (;art > 1) >1992 -esides IC 'ermit usae of aluminium or Co''er for ;rimar3&indins and accordinl3 CTs are desined &ith luminium and more so for B00 Class$

#$0 Current densit3, &hich determines tem'erature rise, &ill -e 'rimar3 consideration of thedesiners irres'ecti8e of material used as also the cross>section area$

B$0 luminium does not react &ith mineral oil and hence anodisation sta-ilit3 is enhanced &hichresults in increased life$

5$0 iid luminium ;rimar3 &indins ca'a-ilit3 to &ithstand d3namic short time current &ill -ehiher$ lso use of luminium -ars for &indins reinforces sta-ilit3 durin fault currents$

$0 In an3 Su-station, conductor 'arts used are of luminium onl3 8i=$ /us>-ars, Terminal

Connectors, transmission lines etc$

7$0 ence desin &ith luminium ;rimar3 ha8e follo&in ad8antaes:>

a) Tem'erature rise is much lo&er$-) /etter short circuit &ithstand Ca'acit3c) /etter ca'a-ilit3 to &ithstand d3namic forces$d) iher Insulation life$

$0 Current Transformers &ith luminium ;rimar3 ha8e -een tested as 'er IS.IC and are inser8ice in India$

FOR CGL MAKE CURRENT TRANSFORMERS :-

%e use aluminium allo3 ( of ecorrosi8e 'ro'ert3 ) riid sections 8i=$ Tu-es,ods, and lats for formin ;rimar3 &indins$ Since ;rimar3 is of aluminium, all the 6oints inthe 'rimar3 &indins are of &elded construction$ it is ro-ust and riid construction, andhence it has ot e


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ADVANTAGES OFFERED BY CROMPTON GREAVES MAKE

LIVE TANK CURRENT TRANSFORMERS

Sr$Fo$ Technical ;arameter d8antaes offered -3 i8e Tan Current Transformer esins

1 Current Status of;roduct Technolo3

%orld e'uted International +anufacturers ha8e onl3 i8eTan esins

2 ih oltae Insulation;ro8ided /et&een;rimar3 D Secondar3

The Insulation is 'ro8ided on Secondar3 %indins, thus the Insulation is al&a3s around m-ient Tem'erature$ Theheat enerated -3 ;rimar3 (&hile carr3in current) is dissi'atedthruG !il to the Tan$ Since Insulation o'erates at oomTem'erature, on uration Sta-ilit3 D elia-ilit3 (Ser8iceife) is assured for the Current Transformers$

# ;rimar3 Conductor The ;rimar3 Conductor is of Short enth (!nl3 H !ne +eterlon for B20) thus E

eat osses due to 'rimar3 current are much less D are'racticall3 nelii-le$

nhanced D Consistent Short Circuit 'erformance as effect oflon lenth return conductor is a-sent in these desins$

ue to nelii-le self>inductance, the Transient rrors at

S3stem ault Current are nelii-le$ Thus true reflection ofault Current on Secondar3 side is achie8ed$ ;henomenon ofocalised Core Saturation due to return conductor of 'rimar3 isnot a''lica-le for i8e Tan CTs$

B Ca'aciti8e ?radin ofInsulation ;ro8ided in;orcelain eion$

+achine %indin of %ider Insulation is feasi-le in i8e TanCTs D thus ine Ca'aciti8e ?raded Insulation can -e'ro8ided$ 75 ?radin oils are 'ro8ided in B20 CT /ushin$This ensures uniformit3 of stress on the insulation in 'orcelain'ortion D thus sinificantl3 enhances Insulation elia-ilit3$

5 Safet3 to the"ui'ments Connectedon Secondar3 D safet3of the !'eratin

;ersonnel

In the unliel3 e8ent of Insulation ailure, The ault Current isdirectl3 led to round throuh iid +etallic ousin (i$e$ Shell)'ro8ided o8er Secondar3 Cores D %indins$ Thus the ner3in the ault Current does not directl3 affect the secondar3

&indins D hence Safet3 is assured for the e"ui'ments D the!'eratin ;ersonnel$

andlin at Site Since ma6orit3 of the &eiht of the CT is closer to the Craneoo, there is no 'ossi-ilit3 s&inin motion &hile main thei8e Tan CT ertical from ori=ontal ;osition$

Sr$Fo$

Technical ;arameter d8antaes offered -3 Crom'ton ?rea8es +ae CurrentTransformers

1 !il olume Com'ensationD ermetic Sealin

Stainless Steel /ello&s are 'ro8ided for com'ensatin !ilolume ariations (due to dail3 am-ient tem'erature chanes) $Insulatin !il in the CT is thus retained as deassed oil$eassed Insulatin !il has hiher 'artial dischare ince'tion8oltae$ ence there is no 'ossi-ilit3 of /u--lin ;henomenon,

&hich enerates 'artial dischares$ Thus on Term Insulationelia-ilit3 is assured$

2 ih oltae Insulation;ro8ided /et&een;rimar3 D Secondar3

!n the head side the Insulation is manuall3 ta'ed$ 2.#rd of themanuall3 -uilt insulation is 'remade on s'ecial 'ur'osemachines$ Thus minimum contamination to the Insulation,assures on Term Insulation elia-ilit3$

# ;rimar3 Conductor D;rimar3 %indins

luminium is used for the ;rimar3 Conductor, ;rimar3Terminals D for the 'rimar3 &indin$ ll the 4oints in the;rimar3 Circuit are %elded , &hich is the -est 6ointin method$

This ensures consistent D elia-le Short Circuit ;erformancefor each CT$

Since the Transmission ine . /us Conductors are madeu' ofluminium , ll luminium Terminal Connectors can -e used ,

thus the ser8ice relia-ilit3 is assured -3 eliminatin there"uirement of /imetallic 4oints


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B Ca'aciti8e ?radin ofInsulation ;ro8ided in;orcelain eion$

%ide /and Insulation %indin techni"ue is used$ This ena-lesus to achie8e finer condenser radin $This ensures uniformit3of stress on the insulation in 'orcelain 'ortion D thussinificantl3 enhances Insulation elia-ilit3$ ;ossi-ilit3 ofInsulation ailure in raile ;orcelain ;ortion is eliminated$

5 iid +etallic ousins

for the Secondar3 Cores

luminium Cast iid Shell is used$ The Shell hal8es are

&elded to each other ll luminium

Construction ll the com'onents on &hich !il Seals are 'ro8ided are made

u' of aluminium$ ence there is no 'ossi-ilit3 of oil leaae dueto ustin of Sealin ?roo8es in Steel Com'onents$ lso thereis no 'ossi-ilit3 of ?as ?eneration due to non>electrical acti8it3$

7 Sealin S3stem Since the Tan is made>u' of luminium, the t&o hal8es of thetan are &elded to each otherE thus one -i sealin aset iseliminated$

%e use iton as the !J in +aterial, &hich is suita-le forcontinuous o'erations u' to 10 de$cent$ Thus the sealinrelia-ilit3 for lo&er tem'erature a''lications is further enhanced$

t all the sealin locations , ! ins are used &hich are dura-ledue to uniform stressin of the ru--er material &hen com'ared

&ith flat asets$ Thus lon term sealin relia-ilit3 is assured$ The num-er of sealin locations are minimised , -3 use of

com'onents such as +ulti Terminal 'o

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Write-up CT