Automatic Power Factor Correction Power Factor 1. 2. 3. !. #. $.

What is Power Factor How Capacitors Work Why Should I Improve My Power Factor What Causes "ow Power Factor Why Should I Improve My Power Factor What Causes "ow Power Factor

Automatic Power Factor Correction (APFC) Panel 1. Power Factor Improvi%&' 2. (hum) *ule i+ HP is k%ow%. 3. ,-.* *e/uired For (ra%s+ormer Compe%satio%' !. Where to co%%ect capacitor' #. Calculatio% o+ re/uired capacitor' $. (esti%& o+ Capacitor at Site' 0. Measureme%t o+ -olta&e' 1. Measureme%t o+ Curre%t' 2. 3ischar&e o+ Capacitor' 14. (ermi%atio% a%d Mou%ti%&' 11. 11. 5se o+ capacitor i% .PFC pa%el 12. 12. Poi%ts should )e veri+ied )e+ore co%sideri%& replaceme%t 13. 13. Poi%ts should )e veri+ied )e+ore char&i%& capacitor )a%ks i%stalled i% parallel or i% .PFC pa%el. 1!. -eri+icatio% Poi%ts i% the i%stallatio% )e+ore commissio%i%& harmo%ic +ilter )a%ks. 1#. I%stallatio% 6uide +or .PFC Pa%el' What is Power Factor Power Factor Definition: Power +actor is the ratio )etwee% the ,W a%d the ,-. draw% )y a% electrical load where the ,W is the actual load power a%d the ,-. is the appare%t load power. It is a measure o+ how e++ectively the curre%t is )ei%& co%verted i%to use+ul work output a%d more particularly is a &ood i%dicator o+ the e++ect o+ the load curre%t o% the e++icie%cy o+ the supply system. .ll curre%t +low causes losses )oth i% the supply a%d distri)utio% system. . load with a power +actor o+ 1.4 results i% the most e++icie%t loadi%& o+ the supply. . load with a power +actor o+7 say7 4.17 results i% much hi&her losses i% the supply system a%d a hi&her )ill +or the co%sumer. . comparatively small improveme%t i% power +actor ca% )ri%& a)out a si&%i+ica%t reductio% i% losses si%ce losses are proportio%al to the s/uare o+ the curre%t. Whe% the power +actor is less tha% o%e the 8missi%&9 power is k%ow% as reactive power which u%+ortu%ately is %ecessary to provide a ma&%eti:i%& +ield re/uired )y motors a%d other i%ductive loads to per+orm their desired +u%ctio%s. *eactive power ca% also )e i%terpreted as wattles7 ma&%eti:i%& or wasted power a%d it represe%ts a% e;tra )urde% o% the electricity supply system a%d o% the co%sumer9s )ill.

. poor power +actor is usually the result o+ a si&%i+ica%t phase di++ere%ce )etwee% the volta&e a%d curre%t at the load termi%als7 or it ca% )e due to a hi&h harmo%ic co%te%t or a distorted curre%t wave+orm. . poor power +actor is &e%erally the result o+ a% i%ductive load such as a% i%ductio% motor7 a power tra%s+ormer7 a%d )allast i% a lumi%ary7 a weldi%& set or a% i%ductio% +ur%ace. . distorted curre%t wave+orm ca% )e the result o+ a recti+ier7 a% i%verter7 a varia)le speed drive7 a switched mode power supply7 dischar&e li&hti%& or other electro%ic loads. . poor power +actor due to i%ductive loads ca% )e improved )y the additio% o+ power +actor correctio% e/uipme%t7 )ut a poor power +actor due to a distorted curre%t wave+orm re/uires a cha%&e i% e/uipme%t 3esi&% or the additio% o+ harmo%ic +ilters. Some i%verters are /uoted as havi%& a power +actor o+ )etter tha% 4.2# whe%7 i% reality7 the true power +actor is )etwee% 4.# a%d 4.0#. (he +i&ure o+ 4.2# is )ased o% the cosi%e o+ the a%&le )etwee% the volta&e a%d curre%t )ut does %ot take i%to accou%t that the curre%t wave+orm is disco%ti%uous a%d there+ore co%tri)utes to i%creased losses. .% i%ductive load re/uires a ma&%etic +ield to operate a%d i% creati%& such a ma&%etic +ield causes the curre%t to )e out o+ phase with the volta&e <the curre%t la&s the volta&e=. Power +actor correctio% is the process o+ compe%sati%& +or the la&&i%& curre%t )y creati%& a leadi%& curre%t )y co%%ecti%& capacitors to the supply. P.F (Cos )= K.W / KVA Or P.F (Cos )= rue Power / A!!arent Power.

KW is Wor"in# Power (also calle$ Actual Power or Acti%e Power or &eal Power). It is the power that actually powers the e/uipme%t a%d per+orms use+ul work. KVA& is &eacti%e Power. It is the power that ma&%etic e/uipme%t <tra%s+ormer7 motor a%d relay=%eeds to produce the ma&%eti:i%& +lu;. KVA is A!!arent Power. It is the >vectorial summatio%? o+ ,-.* a%d ,W. Dis!lacement Power Factor Correction. .% i%ductio% motor draws curre%t +rom the supply that is made up o+ resistive compo%e%ts a%d i%ductive compo%e%ts. (he resistive compo%e%ts are' 1= "oad curre%t. 2= "oss curre%t. .%d the i%ductive compo%e%ts are'

3= "eaka&e reacta%ce. != Ma&%eti:i%& curre%t.

(he curre%t due to the leaka&e reacta%ce is depe%de%t o% the total curre%t draw% )y the motor7 )ut the ma&%eti:i%& curre%t is i%depe%de%t o+ the load o% the motor. (he ma&%eti:i%& curre%t will typically )e )etwee% 24@ a%d $4@ o+ the rated +ull load curre%t o+ the motor. (he ma&%eti:i%& curre%t is the curre%t that esta)lishes the +lu; i% the iro% a%d is very %ecessary i+ the motor is &oi%& to operate. (he ma&%eti:i%& curre%t does %ot actually co%tri)ute to the actual work output o+ the motor. It is the catalyst that allows the motor to work properly. (he ma&%eti:i%& curre%t a%d the leaka&e reacta%ce ca% )e co%sidered passe%&er compo%e%ts o+ curre%t that will %ot a++ect the power draw% )y the motor7 )ut will co%tri)ute to the power dissipated i% the supply a%d distri)utio% system. (ake +or e;ample a motor with a curre%t draw o+ 144 .mps a%d a power +actor o+ 4.0# (he resistive compo%e%t o+ the curre%t is 0# .mps a%d this is what the ,Wh meter measures. (he hi&her curre%t will result i% a% i%crease i% the distri)utio% losses o+ <144 ; 144= A<0# ; 0#= B 1.000 or a 01@ i%crease i% the supply losses. I% the i%terest o+ reduci%& the losses i% the distri)utio% system7 power +actor correctio% is added to %eutrali:e a portio% o+ the ma&%eti:i%& curre%t o+ the motor. (ypically7 the corrected power +actor will )e 4.22 C 4.2# Power +actor correctio% is achieved )y the additio% o+ capacitors i% parallel with the co%%ected motor circuits a%d ca% )e applied at the starter7 or applied at the switch)oard or distri)utio% pa%el. (he resulti%& capacitive curre%t is leadi%& curre%t a%d is used to ca%cel the la&&i%& i%ductive curre%t +lowi%& +rom the supply.

Dis!lacement 'tatic Correction ('tatic Com!ensation). .s a lar&e proportio% o+ the i%ductive or la&&i%& curre%t o% the supply is due to the ma&%eti:i%& curre%t o+ i%ductio% motors7 it is easy to correct each i%dividual motor )y co%%ecti%& the correctio% capacitors to the motor starters.

With static correctio%7 it is importa%t that t(e ca!aciti%e current is less t(an t(e in$ucti%e ma#neti)in# current of t(e in$uction motor. I% ma%y i%stallatio%s employi%& static power +actor correctio%7 the correctio% capacitors are co%%ected directly i% parallel with the motor wi%di%&s. Whe% the motor is D++ "i%e7 the capacitors are also D++ "i%e. Whe% the motor is co%%ected to the supply7 the capacitors are also co%%ected providi%& correctio% at all times that the motor is co%%ected to the supply. (his removes the re/uireme%t +or a%y e;pe%sive power +actor mo%itori%& a%d co%trol e/uipme%t. I% this situatio%7 the capacitors remai% co%%ected to the motor termi%als as the motor slows dow%. .% i%ductio% motor7 while co%%ected to the supply7 is drive% )y a rotati%& ma&%etic +ield i% the stator which i%duces curre%t i%to the rotor. Whe% the motor is disco%%ected +rom the supply7 there is +or a period o+ time7 a ma&%etic +ield associated with the rotor. .s the motor decelerates7 it &e%erates volta&e out its termi%als at a +re/ue%cy which is related to its speed. (he capacitors co%%ected across the motor termi%als7 +orm a reso%a%t circuit with the motor i%ducta%ce. I+ the motor is critically corrected7 <corrected to a power +actor o+ 1.4= the i%ductive reacta%ce e/uals the capacitive reacta%ce at the li%e +re/ue%cy a%d there+ore the reso%a%t +re/ue%cy is e/ual to the li%e +re/ue%cy. I+ the motor is over corrected7 the reso%a%t +re/ue%cy will )e )elow the li%e +re/ue%cy. I+ the +re/ue%cy o+ the volta&e &e%erated )y the decelerati%& motor passes throu&h the reso%a%t +re/ue%cy o+ the corrected motor7 there will )e hi&h curre%ts a%d volta&es arou%d the motorAcapacitor circuit. (his ca% result i% severe dama&e to the capacitors a%d motor. It is imperative that motors are %ever over corrected or critically corrected whe% static correctio% is employed. 'tatic !ower factor correction s(oul$ !ro%i$e ca!aciti%e current e*ual to +,- of t(e ma#neti)in# current. which is esse%tially the ope% sha+t curre%t o+ the motor. (he ma&%eti:i%& curre%t +or i%ductio% motors ca% vary co%sidera)ly. (ypically7 ma&%eti:i%& curre%ts +or lar&e two !ole mac(ines can /e as low as 0,- of t(e rate$ current of t(e motor w(ile smaller low s!ee$ motors can (a%e a ma#neti)in# current as (i#( as 1,- of t(e rate$ full loa$ current of t(e motor Where the ope% sha+t curre%t ca%%ot )e measured7 a%d the ma&%eti:i%& curre%t is %ot /uoted7 a% appro;imate level +or the ma;imum correctio% that ca% )e applied ca% )e calculated +rom the hal+ load characteristics o+ the motor. It is da%&erous to )ase correctio% o% the +ull load characteristics o+ the motor as i% some cases7 motors ca% e;hi)it a hi&h leaka&e reacta%ce a%d correctio% to 4.2# at +ull load will result i% over correctio% u%der %o load7 or disco%%ected co%ditio%s. Static correctio% is commo%ly applied )y usi%& o% e co%tactor to co%trol )oth the motor a%d the capacitors. It is )etter practice to use two co%tactors7 o%e +or the motor a%d o%e +or the capacitors. Where o%e co%tactor is employed7 it should )e up si:ed +or the capacitive load. (he use o+ a seco%d co%tactor elimi%ates the pro)lems o+ reso%a%ce )etwee% the motor a%d the capacitors. How Capacitors Work

I%ductio% motors7 tra%s+ormers a%d ma%y other electrical loads re/uire ma&%eti:i%& curre%t <kvar= as well as actual power <kW=. Ey represe%ti%& these compo%e%ts o+ appare%t power <k-.= as the sides o+ a ri&ht tria%&le7 we ca% determi%e the appare%t power +rom the ri&ht tria%&le rule' k-.2 B kW2 F k-.*2. (o reduce the kva re/uired +or a%y &ive% load7 you must shorte% the li%e that represe%ts the kvar. (his is precisely what capacitors do. Ey supplyi%& kvar ri&ht at the load7 the capacitors relieve the utility o+ the )urde% o+ carryi%& the e;tra kvar. (his makes the utility tra%smissio%Adistri)utio% system more e++icie%t7 reduci%& cost +or the utility a%d their customers. (he ratio o+ actual power to appare%t power is usually e;pressed i% perce%ta&e a%d is called power +actor. What Causes "ow Power Factor Si%ce power +actor is de+i%ed as the ratio o+ ,W to ,-.7 we see that low power +actor results whe% ,W is small i% relatio% to ,-.. I%ductive loads. I%ductive loads <which are sources o+ *eactive Power= i%clude' 1. 2. 3. !. (ra%s+ormers I%ductio% motors I%ductio% &e%erators <wi%d mill &e%erators= Hi&h i%te%sity dischar&e <HI3= li&hti%&

(hese i%ductive loads co%stitute a maGor portio% o+ the power co%sumed i% i%dustrial comple;es. *eactive power <,-.*= re/uired )y i%ductive loads i%creases the amou%t o+ appare%t power <,-.= i% your distri)utio% system .(his i%crease i% reactive a%d appare%t power results i% a lar&er a%&le <measured )etwee% ,W a%d ,-.=. *ecall that7 as i%creases7 cosi%e <or power +actor= decreases. Why Should I Improve My Power Factor Hou wa%t to improve your power +actor +or several di++ere%t reaso%s. Some o+ the )e%e+its o+ improvi%& your power +actor i%clude' 2) 3ower utilit4 fees /4: (a). &e$ucin# !ea" KW /illin# $eman$: I%ductive loads7 which re/uire reactive power7 caused your low power +actor. (his i%crease i% re/uired reactive power <,-.*= causes a% i%crease i% re/uired appare%t power <,-.=7 which is what the utility is supplyi%&. So7 a +acility9s low power +actor causes the utility to have to i%crease its &e%eratio% a%d tra%smissio% capacity i% order to ha%dle this e;tra dema%d. Ey loweri%& your power +actor7 you use less ,-.*. (his results i% less ,W7 which e/uates to a dollar savi%&s +rom the utility. (/). 5liminatin# t(e !ower factor !enalt4:

5tilities usually char&e customers a% additio%al +ee whe% their power +actor is less tha% 4.2#. <I% +act7 some utilities are %ot o)li&ated to deliver electricity to their customer at a%y time the customer9s power +actor +alls )elow 4.1#.= (hus7 you ca% avoid this additio%al +ee )y i%creasi%& your power +actor. 0) 6ncrease$ s4stem ca!acit4 an$ re$uce$ s4stem losses in 4our electrical s4stem Ey addi%& capacitors <,-.* &e%erators= to the system7 the power +actor is improved a%d the ,W capacity o+ the system is i%creased. For e;ample7 a 17444 ,-. tra%s+ormer with a% 14@ power +actor provides 144 ,W <$44 ,-.*= o+ power to the mai% )us. Ey i%creasi%& the power +actor to 24@7 more ,W ca% )e supplied +or the same amou%t o+ ,-.. 1444 ,-. B ,-.* B !3$ (he ,W capacity o+ the system i%creases to 244 ,W a%d the utility supplies o%ly !3$ ,-.*. 5%corrected power +actor causes power system losses i% your distri)utio% system. Ey improvi%& your power +actor7 these losses ca% )e reduced. With the curre%t rise i% the cost o+ e%er&y7 i%creased +acility e++icie%cy is very desira)le. .%d with lower system losses7 you are also a)le to add additio%al load to your system. 7) 6ncrease$ %olta#e le%el in 4our electrical s4stem an$ cooler. more efficient motors .s me%tio%ed a)ove7 u%corrected power +actor causes power system losses i% your distri)utio% system. .s power losses i%crease7 you may e;perie%ce volta&e drops. I;cessive volta&e drops ca% cause overheati%& a%d premature +ailure o+ motors a%d other i%ductive e/uipme%t. So7 )y raisi%& your power +actor7 you will mi%imi:e these volta&e drops alo%& +eeder ca)les a%d avoid related pro)lems. Hour motors will ru% cooler a%d )e more e++icie%t7 with a sli&ht i%crease i% capacity a%d starti%& tor/ue. .utomatic Power Factor Correctio% <.PFC= Pa%el Power Factor 6m!ro%in#: 1. Please check i+ re/uired k-.r o+ capacitors are i%stalled. 2. Check the type o+ capacitor i%stalled is suita)le +or applicatio% or the capacitors are de rated. 3. Check i+ the capacitors are perma%e%tly 8DJ9. (he Capacitor are %ot switched o++ !. whe% the load is %ot worki%&7 u%der such co%ditio% the avera&e power +actor is +ou%d to )e lower side. <244 ,W=2 F < ,-.*=2

#. Check whether all the capacitors are operated i% .PFC depe%di%& upo% the load operatio%. $. Check whether the .PFC i%stalled i% the i%stallatio% is worki%& or %ot. Check the C( co%%ectio% is take% +rom the mai% i%comer side o+ tra%s+ormer7 a+ter the +i; compe%satio% o+ tra%s+ormer. 0. Check i+ the load dema%d i% the system is i%creased. 1. Check i+ power tra%s+ormer compe%satio% is provided. (um/ &ule if 8P is "nown. (he compe%satio% +or motor should )e calculated taki%& the details +rom the rati%& plate o+ motor Dr t(e ca!acitor s(oul$ /e rate$ for 2/7 of 8P

1. I%sure the capacitor is protected usi%& +use A MCE. 2. (he capacitor is switched 9O:; alo%& with starter 3. I% case o+ starKdelta starter the capacitor should switch 9O:; o% delta mode. K%ar &e*uire$ For ransformer LB 31# k-. (.C 31#k-. (o 1444 k-. MB 1444 k-. ransformer Com!ensation: &e*uire$ K%a B #@ o+ ,-. B $@ o+ ,-. B 1@ o+ ,-.

W(ere to connect ca!acitor: Fi; compe%satio% should )e provided to take care o+ power tra%s+ormer. Power a%d distri)utio% tra%s+ormers7 which work o% the pri%ciple o+ electroK ma&%etic i%ductio%7 co%sume reactive power +or their ow% %eeds eve% whe% its seco%dary is %ot co%%ected to a%y load. (he power +actor will )e very low u%der such situatio%. (o improve the power +actor it is re/uired to co%%ect a +i;ed capacitor or capacitor )a%k at the "( side o+ the (ra%s+ormer. For appro;imate k-.r o+ capacitors re/uired I+ the i%stallatio% is havi%& various small loads with the mi;ture o+ lar&e loads the% the .PFC should )e recomme%ded. Jote that .PFC should have mi%imum step rati%& o+ 14@ as smaller step. I+ loads are small the% the capacitor should )e co%%ected parallel to load. (he co%%ectio% should )e such that whe%ever the loads are switched o% the capacitor also switches o% alo%& with the load. Jote that .PFC pa%el ca% mai%tai% the power +actor o% ".( side o+ tra%s+ormer a%d it is %ecessary to provide +i; compe%satio% +or Power tra%s+ormer. I% case there is %o tra%s+ormer i% the i%stallatio%7 the% the C.( +or se%si%& power +actor should )e provided at the i%comi%& o+ mai% switch o+ the pla%t.

Calculatio% o+ re/uired capacitor'

Suppose .ctual P.F is 4.17 *e/uired P.F is 4.21 a%d (otal "oad is #1$,-.. Power factor = "w( / "%a( "W = "VA < Power Factor B #1$ ; 4.1 B !12.1 &e*uire$ ca!acitor = "W < =ulti!l4in# Factor B <4.1 ; #1$= ; Multiplyi%& Factor B !12.1 ; 4.#!0 <See (a)le to +i%d -alue accordi%& to P.F 4.1 to P.F o+ 4.21= = 00>.+, "Var =ulti!l4in# factor for calculatin# "VAr ar#et PF ,.1 ,.1 ,.? ,.?2 ,.?0 ,.?7 ,.?@ ,.?> ,.?1 ,.?A ,.?+ ,.?? 2

4.1!2 4.101 4.240 4.231 4.204 1.44# 1.4!2 1.413 1.134 1.121 1.333

,.12 4.11# 4.1!3 4.103 4.24! 4.23$ 4.204 1.440 1.4!1 1.42$ 1.1#0 1.222 ,.10 4.011 4.114 4.132 4.104 4.243 4.230 4.20! 1.41# 1.4$2 1.123 1.2$# ,.17 4.0!1 4.000 4.140 4.130 4.104 4.24! 4.2!1 4.212 1.434 1.424 1.233 ,.1@ 4.01$ 4.0!# 4.00# 4.14# 4.131 4.102 4.242 4.2#4 4.221 1.4#1 1.241 ,.1> 4.$1# 4.01! 4.0!3 4.00! 4.14$ 4.1!4 4.100 4.212 4.2$$ 1.420 1.1$2 ,.11 4.$#! 4.$13 4.012 4.0!3 4.00# 4.114 4.1!0 4.111 4.23# 4.22$ 1.131 ,.1A 4.$2! 4.$#2 4.$12 4.013 4.0!# 4.002 4.11$ 4.1#0 4.24# 4.2$$ 1.141 ,.1+ 4.#2! 4.$23 4.$#2 4.$13 4.01# 4.0#4 4.010 4.121 4.10# 4.23$ 1.401 ,.1? 4.#$# 4.#23 4.$23 4.$#! 4.$1$ 4.024 4.0#0 4.021 4.1!$ 4.240 1.4!2 ,.A 4.#3$ 4.#$# 4.#2! 4.$2# 4.$#0 4.$22 4.022 4.004 4.110 4.101 1.424 ,.A2 4.#41 4.#3$ 4.#$$ 4.#20 4.$22 4.$$3 4.044 4.0!1 4.012 4.1!2 4.222 ,.A0 4.!14 4.#41 4.#31 4.#$2 4.$41 4.$3# 4.$02 4.013 4.0$1 4.121 4.2$! ,.A7 4.!#2 4.!11 4.#14 4.#!1 4.#03 4.$41 4.$!# 4.$1$ 4.033 4.02! 4.23$ ,.A@ 4.!2# 4.!#3 4.!13 4.#1! 4.#!$ 4.#14 4.$10 4.$#1 4.04$ 4.0$$ 4.242 ,.A> 4.321 4.!2$ 4.!#$ 4.!10 4.#12 4.##3 4.#24 4.$31 4.$02 4.032 4.112 ,.A1 4.301 4.!44 4.!22 4.!$4 4.!22 4.#2$ 4.#$3 4.$4# 4.$#2 4.013 4.1## ,.AA 4.3!! 4.303 4.!43 4.!33 4.!$$ 4.#44 4.#30 4.#01 4.$2$ 4.$1$ 4.122 ,.A+ 4.311 4.3!0 4.30$ 4.!40 4.!32 4.!0! 4.#11 4.##2 4.#22 4.$$4 4.142 ,.A? 4.222 4.324 4.3#4 4.311 4.!13 4.!!0 4.!1! 4.#2# 4.#03 4.$3! 4.00$ ,.+ 4.2$$ 4.22! 4.32! 4.3## 4.310 4.!21 4.!#1 4.!22 4.#!0 4.$41 4.0#4 ,.+2 4.2!4 4.2$1 4.221 4.322 4.3$1 4.32# 4.!32 4.!03 4.#21 4.#11 4.02! ,.+0 4.21! 4.2!2 4.202 4.343 4.33# 4.3$2 4.!4$ 4.!!0 4.!2# 4.##$ 4.$21

,.+7 4.111 4.21$ 4.2!$ 4.200 4.342 4.3!3 4.314 4.!21 4.!$2 4.#34 4.$02 ,.+@ 4.1$2 4.124 4.224 4.2#1 4.213 4.310 4.3#! 4.32# 4.!!3 4.#43 4.$!$ ,.+> 4.13# 4.1$! 4.12! 4.22# 4.2#0 4.221 4.321 4.3$2 4.!10 4.!00 4.$24 ,.+1 4.142 4.131 4.1$0 4.121 4.234 4.2$# 4.342 4.3!3 4.324 4.!#1 4.#23 ,.+A 4.412 4.111 4.1!1 4.102 4.24! 4.231 4.20# 4.31$ 4.3$! 4.!2! 4.#$0 ,.++ 4.4## 4.41! 4.11! 4.1!# 4.100 4.211 4.2!1 4.212 4.330 4.320 4.#!4 ,.+? 4.421 4.4#0 4.41$ 4.110 4.1!2 4.11! 4.221 4.2$2 4.342 4.304 4.#12 ,.? ,.?2 ,.?0 ,.?7 ,.?@ ,.?> (esti%& o+ Capacitor at Site' =easurement of Volta#e: Check the volta&e usi%& multi meter at capacitor termi%als. Please %ote that the curre%t output o+ !!4 volt capacitor co%%ected to a system o+ !1# volt will )e lesser tha% rated value. (a)le %o K1 N 2 &ive you the resulta%t k-.r output o+ the capacitor due to variatio% i% supply volta&e. (he k-.r o+ capacitor will %ot )e same i+ volta&e applied to the capacitor a%d +re/ue%cy cha%&es. (he e;ample &ive% )elow shows how to calculate capacitor curre%t +rom the measured value at site. 4.422 4.4#1 4.412 4.121 4.1#$ 4.123 4.23! 4.211 4.3!2 4.!1! 4.434 4.4$4 4.423 4.120 4.1$! 4.24# 4.2#3 4.313 4.!#$ 4.431 4.4$3 4.420 4.13! 4.10# 4.223 4.21! 4.!2$ 4.432 4.4$0 4.14! 4.1!# 4.122 4.2#3 4.32# 4.43! 4.401 4.112 4.1$4 4.224 4.3$3 4.430 4.401 4.12$ 4.11$ 4.322

I;ample ' 1. Jame plate details C 1#k-.r7 3 phases7 !!4v7 a%d #4H: capacitor. Measured volta&e C !2#v 7 Measured +re/ue%cy C !1.#H: K%ar = (f= / f&) < (V= / V&)0 < "%ar ,var B <!1.#A#4= ; <!2# A !!4=0 ; 1# B 13.#0k-.r. 2. Jame plate details C 1#k-.r7 3 phases7 !1#v7 a%d #4H: capacitor. Measured volta&e C !2#v7 Measured +re/ue%cy C !1.#H: ,var B <+M A +*= ; <-M A -*=0 ; k-.r ,var B <!1.#A#4= ; <!2# A !1#=0 ; 1#

B 1#.2$k-.r (ree P(ase @@,V Ca!acitor "VAr @@,V 3ine current @@,V # 0.# 14 12.# 1# 24 2# $.#$ 2.1! 13.12 1$.! 12.$1 2$.2! 32.14 "VAr at @2>V !.!# $.$0 1.24 11.12 1373! 10.02 22.2! =easure$ ca!acitance across two terminals 3ine Current wit( t(ir$ terminal at @2>V o!en.(=icro fara$) @@,V $.111 2.21 12.31 1#.!0 11.#$ 2!.0# 34.2! !1.14 $1.$$ 12.21 142.0$ 123.31 1$!.!2 24#7#2

(ree P(ase @2>V Ca!acitor "VAr @2>V 3ine current @2>V # 0.# 14 12.# 1# 24 2# $.## 14.!3 13.21 10.32 24.10 20.12 3!.01 "VAr at @@,V #.$2 1.!3 11.2! 1!.4# 1$.1$ 22.!1 31.14 =easure$ ca!acitance across two terminals 3ine Current wit( t(ir$ terminal at @2>V o!en.(=icro fara$) @2>V 0.31 11.4$ 1!.0# 11.!! 22.13 22.#4 3$.11 !$.21 $2.31 22.!1 11$.#1 131.$2 11!.12 231.43

Measureme%t o+ Curre%t' (he capacitor curre%t ca% )e measured usi%& Multi meter. Make a record o+ measureme%t data o+ i%dividual phase a%d other parameter. Check whether the curre%t measured is withi% the limit value with respect to supply volta&e N data &ive% i% the %ame plate o+ capacitor *e+er +ormula +or calculatio% Formula +or calculati%& rated curre%t o+ capacitor with rated supply volta&e a%d +re/ue%cy.

l = "%ar < 2,7 / ( 7 B V ) 3 3 5<am!le:

1#k-.r7 3 phase7 !!4v7 #4H: capacitor. l B k-.r ; 147 A < 3 O - = 3 3 l B <1# ; 1444= A <1.032 ; !!4= 3 l B 12.$1.MPs 3 1#k-.r7 3 phases7 !1#v7 #4H: capacitor l B k-.r ; 147A < 3 O - = 3 3 l B <1# ; 1444= A <1.032 ; !1#= 3 l B 24.10 .mps 3ischar&e o+ Capacitor' ".( power capacitors are provided with dischar&e resistor to dischar&e the capacitor which is limited to o%e mi%. (he resistor are provided as per clause JoK0.1 o+ IS 133!4K1223. Switch o++ the supply to the capacitor a%d wait +or 1 mi%ute a%d the% short the termi%als o+ capacitor to e%sure that the capacitor is completely dischar&ed. (his shorti%& o+ termi%als e%sures the sa+ety while ha%dli%& the capacitor 3ischar&e o+ capacitor also )ecomes %ecessary +or the sa+ety o+ meter used +or capacita%ce measureme%t.

(ermi%atio% a%d Mou%ti%&' 5se suita)le si:e lu&s +or co%%ecti%& the ca)le to the termi%als o+ capacitor. I%sure that there is %o loose co%%ectio%' .s loose co%%ectio% may lead to +ailure o+ capacitor A i%sulatio% )reak dow% o+ ca)le. 5se proper tools +or co%%ectio% A ti&hte%i%&. I%sure that the capacitor is mou%ted vertically. (he earthi%& o+ capacitor should )e do%e )e+ore char&i%&. (he applied volta&e should %ot e;ceed more tha% 14@. *e+er tech%ical speci+icatio% o+ capacitor. (he capacitor should )e provided with the short circuit protectio% device as i%dicated i% +ollowi%& (a)le 8&C Fuse 12 .mps 2# .mps 32 .mps 32 .mps #4 .mps #4 .mps Ca/le Am!s 12 .mps 2# .mps 32 .mps 32 .mps #4 .mps #4 .mps

KVAr # 0.# 14 12.# 1# 24

2# #4 0# 144

$3 .mps 12# .mps 244 .mps 244 .mps

$3 .mps 12# .mps 244 .mps 2#4 .mps

5se o+ capacitor i% .PFC pa%el (he capacitor should )e provided with suita)le desi&%ed i%rush curre%t limiti%& i%ductor coils or special capacitor duty co%tactors. .%%e;ure d poi%t %o dK0.1 o+ IS 133!4K1223 D%ce the capacitor is switched o++ it should %ot )e switched o% a&ai% withi% $4 seco%ds so that the capacitor is completely dischar&ed. (he switchi%& time i% the relay provided i% the .PFC pa%el should )e set +or $4 seco%ds +or i%dividual steps to dischar&e. Clause JoK0.1 o+ IS 133!4K1223 I+ the capacitor is switched ma%ually or i+ you are switchi%& capacitors co%%ected i% parallel with each other the% >DJ? delay timer <$4sec= should )e provided a%d i% case o+ parallel operatio% o%ce a&ai% poi%t Jo 1 should )e take% care. Clause JoK0.1 o+ IS 133!4K1223 (he capacitor mou%ted i% the pa%el should have mi% &ap o+ 2#K34 mm )etwee% the capacitor a%d #4 mm arou%d the capacitor to the pa%el e%closure. I% case o+ )a%ki%& a mi% &ap o+ 2#mm )etwee% the phase to phase a%d 12mm )etwee% the phases to earth should )e mai%tai%ed. I%sure that the )a%ki%& )us )ar is rated +or 1.1 times rated curre%t o+ )a%k. (he pa%el should have provisio% +or cross ve%tilatio%7 the louver A +a% ca% )e provided i% the care .%%e;ure d poi%t Jo dK3.1 IS 133!4K1223 For use o+ reactor a%d +ilter i% the pa%el +a% should )e provided +or cooli%&. Short circuit protectio% device <H*C +use A MCCE= should %ot e;ceed 1.1 ; rated curre%t o+ capacitor. I% case o+ detu%ed +ilter )a%ks MCCE is recomme%ded +or short circuit protectio%.

Points s(oul$ /e %erifie$ /efore consi$erin# re!lacement Supply volta&e to capacitor should )e checked +or a%y over volta&e. (his ca% )e veri+ied o+ volta&e sta)ili:ers are co%%ected i% the i%stallatio%7 li&ht +itti%& are re&ularly replaced7 this i%dicates the over volta&e. It is &e%erally +ou%d that i.c. )ase .PFC relays are )i& i% si:e as compared to microprocessor relays. (hese ic )ased relays are +ou%d to )e mal+u%ctio%i%&. (he capacitors are switched >DFF? N >DJ? very +ast without dischar&e o+ capacitor7 leadi%& to hi&h curre%t draw% )y capacitors. Such operatio% leads to +ailure o+ capacitor. Check the time set i% .PFC relays co%%ected +or the operatio%7 as various make o+ relays are preset +or 1#K24 sec. (his setti%& o+ time should )e veri+ied i% prese%ce o+ customer at pa%el with operatio% o+ relay. (he switchi%& o+ capacitor +rom o%e step to a%other should have mi% time &ap o+ $4 seco%d. (his should )e physically watched. Jo replaceme%t shall )e co%sidered i% such cases where i% the time is set )elow $4sec. (he chatteri%& o+ co%tactor ca% also lead to +ailure o+ capacitor. (his chatteri%& may happe% due to low volta&e or loose co%%ectio% to co%tactor

coils etc. I+ the capacitors are operated i% ma%ual mode usi%& push )utto%7 check whether the o% delay timer is provided i% the i%dividual steps. -eri+y whether the time set o+ $4sec or %ot. Jo replaceme%t should )e co%sidered i% such cases where i% the timer is set )elow $4sec. or it is %ot provided. Check whether capacitor duty co%tactor is provided or i+ the i%rush limiti%& i%ductor coils are used. (his )ecomes importa%t i% case the capacitors are switched 8DJ9 with the other capacitor co%%ected i% the same )us. Parallel switchi%& o+ capacitor is &e%erally +ou%d i% capacitor pa%els havi%& .PFC a%d push )utto%s +or switchi%& >o%? N >o++?. Check whether the harmo%ic is prese%t. For this take a +resh capacitor7 char&e the capacitor a%d the% calculate whether the curre%t draw% )y capacitor is withi% the limit. I+ the curre%t is more7 the% it may )e due to over volta&e. I+ %ot the% it is clear that the capacitor is drawi%& hi&h curre%t due to prese%ce o+ harmo%ics. (he harmo%ics i% the pla%t ca% )e easily +ou%d I+ the pla%t has loads usi%& power electro%ic compo%e%ts such as ups7 drives a%d +ur%ace. "oads such as are weldi%&7 c+l tu)es a%d electro%ic co%trolled machi%es also &e%erate harmo%ics. Jote that %ei&h)ori%& pla%t co%%ected to the &rid may also a++ect the capacitors )y importi%& the harmo%ic. <Harmo%ic volta&e easily travels throu&h the &rid +rom o%e i%stallatio% to a%other7 the e++ect o+ such volta&e leads to +ailure o+ capacitor=. Check other poi%ts &ive% i% i%stallatio% &uide li%e o+ capacitor. I% case the i%stallatio% is havi%& M3KO" capacitors with co%%ected loads &e%erati%& harmo%ics the% the capacitor may )e drawi%& additio%al 34@ curre%t. I% such co%ditio%s the +uses may )low out ca)le will heat up a%d (emperature o+ capacitor will )e also i%creased. I%sure that the +use rati%& should %ot )e i%creased. (he switch&ear a%d ca)le si:e should )e suita)ly i%creased. (he capacitor will co%ti%ue to work )ut the li+e o+ capacitor may %ot )e lo%&er. (his clearly i%dicates that the capacitor is over loaded a%d i+ re/uired the reactor

Should )e provided +or co%trolli%& the over curre%t. Check the short circuit protectio% device. Please %ote that you may come across the customer usi%& +uses almost dou)le the curre%t rati%& o+ capacitors. (his is &e%erally +ou%d i% the pla%ts havi%& harmo%ic pro)lems a%d the i%stallatio%s havi%& hired local electricia%s +or mai%te%a%ce. Check the date o+ i%stallatio% o+ capacitor a%d type o+ additio%al load )ei%& co%%ected a+ter i%stallatio% o+ capacitors. .s it is o)served i% certai% cases that the type o+ capacitor was selected without co%sideri%& +uture e;pa%sio% o+ machi%eries i% the pla%t. Some time these machi%es are +ou%d to )e &e%erati%& harmo%ic a++ecti%& the li+e o+ capacitor. Jo replaceme%t should )e co%sidered i+ capacitor is +ailed due to harmo%ics a%d customer has used %ormal capacitors without co%sulti%& I%&i%eers.

Points s(oul$ /e %erifie$ /efore c(ar#in# ca!acitor /an"s installe$ in !arallel or in APFC !anel. Capacitor volta&e rati%& is e/ual to the ma; volta&e recorded i% the i%stallatio%. Capacitor is mou%ted vertically.

Iarthi%& at two di++ere%t poi%ts is do%e. Proper lu&s are used +or termi%atio%. Proper si:e o+ ca)le is used. PhK ph &ap is 2#mm a%d phKearth is 12mm. (he )us )ar used +or )a%ki%& is 1.1 ; rated curre%t o+ the )a%k. Cross ve%tilatio% provisio% is provided i% the i%stallatio% area A i% the pa%el. (he pla%t has the +acility to trip the capacitor u%der over volta&e co%ditio%s. <14@= Capacitor is provided with suita)le si:e o+ H*C +use A MCCE rati%& +or protectio%. Suita)le i%rush curre%t device is co%%ected i% series with co%tactor to limit the i%rush curre%t or capacitor duty co%tactor is used. Capacitor is provided with suita)le o% delay timer to e%sure that the capacitor is %ot switched o% withi% $4sec. .+ter it is switched o++. Capacitor is provided with i%sulati%& cover to e%sure the sa+ety. Capacitor is i%stalled i% the area +ree +rom e%try o+ dust7 chemical +ume a%d rai% water. .PFC relay provided i% the pa%el is set +or $4 seco%d. 8D% delay9 provided are also set +or $4 seco%d. (he +ilter )a%ks are provided with MCCE +or protectio% apart +rom a)ove poi%ts. (he MCCE should )e set +or 1.3 ; rated curre%t o+ +ilter )a%k

Verif4 t(e followin# in t(e installation /efore commissionin# (armonic filter /an"s. Capacitor )a%ks without reactor should %ot )e permitted o% the seco%dary si:e o+ tra%s+ormer circuit which is havi%& +ilter )a%ks co%%ected. Please remove capacitors without reactors +rom the same %etwork <as IICK $1$!2=. Filter rated volta&e is e/ual to the ma; volta&e recorded i% the i%stallatio%. Capacitor used with reactors is always o+ special volta&e recorded i% the i%stallatio%. Iarthi%& should )e do%e at capacitors a%d reactors separately. Proper lu&s are used +or termi%atio%. Proper si:e o+ ca)le is used. PhK ph &ap is 2#mm a%d phKearth is 12mm. (he )us )ar used +or )a%ki%& is 1.1 ; rated )a%k curre%t. Forced cross ve%tilatio% should )e provided i% the i%stallatio% area. (he pla%t has the +acility to trip the +ilter )a%ks u%der over volta&e co%ditio%s. Set +or 14@ over volta&e. Filter )a%ks are provided with suita)le si:e o+ MCCE rati%& +or protectio%. (he MCCE is set +or 1.3 ; rated curre%t o+ +ilter )a%k. MCCE are recomme%ded. Filter is provided with suita)le 8o% delay9 timer to e%sure that the capacitor is %ot switched o% withi% $4sec. .+ter it is switched o++. Filter is i%stalled i% the area +ree +rom e%try o+ dust7 chemical +umes a%d rai% water. .PFC relay provided i% the pa%el +or switchi%& +ilters is set +or $4 seco%d.

I%stallatio% 6uide +or .PFC Pa%el'

Shi+t the pa%el to the locatio% where it is re/uired to )e i%stalled. <a= Positio% the pa%el o% the +ou%datio% a%d lock the pa%el )ase +rame with the +ou%datio% )olts +or +ree sta%di%& pa%els7 )y usi%& spirit level a%d plum)er )lock +or achievi%& hori:o%tal a%d vertical leveli%&. <)= Positio% pa%el o+ the wall A structure a%d +i; with wall mou%ti%& )rackets provided alo%& with the pa%el. "eveli%& should )e do%e here also as e;plai%ed a)ove. Co%%ect the earth co%ductor to the pa%el termi%al provided o% either side o+ the pa%el. 5se the key provided to ope% the door o+ the pa%el make sure that electrical co%%ectio%s o+ all e/uipme%ts are i%tact. (his is particularly importa%t si%ce vi)ratio% i% tra%sportatio% sometimes may have resulted i% loose co%%ectio%s. 5si%& a star screw driver7 ope% the rear door o+ the +ree sta%di%& pa%el. Make two %um)er suita)le cut outs +or 3.# core power ca)le a%d 2 cores 2. S/ mm cooper multi sta%d C.( co%trol ca)le i% the &la%d plate provided. . 5si%& suita)le si:e o+ ca)le &la%d co%%ect the ca)les. I%sure that the ca)le &la%d is +i;ed properly without a%y &aps i% the &la%d plate +or proper seali%& o+ the ope%i%& to preve%t a%y e%try o+ vermi%9s. (he ca)le rated +or curre%t capacity e/uivale%t to mai% i%comer o+ pa%el should )e used. 5se suita)le si:e lu&s +or co%%ecti%& the power ca)les. Co%%ect the ca)le to the termi%als provided +or the power supply. Make sure that the correct phase ide%ti+icatio% is mai%tai%ed while co%%ectio% to the i%comi%& termi%als to the pa%el with respect to phases o+ supply li%e. .s a%y mistake will lead to the mal+u%ctio%i%& o+ relay. Co%%ect the 8*9 phase C.( ca)le to the termi%als provided. +or power co%%ectio% a%d C.( locatio%. (he relay is preKset +or a seco%dary curre%t output o+ #.. I% case the C.( seco%dary is 1 .mps the% cha%&e.