UsingFusestoIncreaseSCCR.pdf

7/29/2019 UsingFusestoIncreaseSCCR.pdf

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USING

CURRENT-LIMITING

FUSES TO

INCREASE SCCR



Using CUrrent-limiting FUses to inCrease sCCr

2www.litteluse.com/sccr

Eecutive Summarya d c cc auh Hv Judc

(aHJ) h hv dpd h 2005 2008 d h

n ecc Cd® (neC®)1 qu du c

p b kd wh sh Ccu Cu r

(sCCr). sc 2006 Ul ld du c p

w kd d bd wh sh Ccu Cu r.

th sh Ccu Cu r h xu cu

h c p c y whd whu xcv

d. i h vb u cu h cc y

wh h p d xcd h sCCr h p

d h ccu ccu, cphc d h

p y ccu d cc wk d h pu

k juy. i h pby h cu cc d vy h du c

p ppd uch h h p’ sCCr

h h y’ vb u cu. i h

pby h du c p ucu

pvd ccu sCCr h cu

d auhy Hv Judc huh qud b d

pubhd chc .

accd h n ecc Cd® h du

c p ucu c d p’ sCCr

u w hd. o wy h p

bd sCCr wd by n

rczd t lb (nrtl). th hd

h h ucu c u ppy h ddzdb Ul508 a, dd du c p. th

chc p bh h hd cvd

d h pp.

th quy d- bw yu

p ppy h Ul508 a b. By u cu-

dvc d yu p, yu w ypcy chv

hh sCCr yu p. Hwv, bcu ch uqu

p d d b d, ucu,

h hd c bc phbvy xpv d

cu. i h c, h Ul508 a b hd y

b ud.

Fy, h ccu cu p c b

cd wh c pd h sCCr h d . By u cu- ccu pc

dvc d cuy c h hh whd d

cp, h sCCr h p c b cd

v ccpb cu d pc.

th c ppuy cv ucu wh

d d cpb bud cpv dv

hh sCCr vy p hy d d ucu.

What is a SCCR?th sh Ccu Cu r h xu

cu, uuy xpd ka pcd v, h

dvc y c y whd pcd

(uch 0.05 cd), u pcd u

ccu bk p d c h ccu. my Ul

ppvd dvdu pw cp uch cc,

vd y, d c kd wh

sCCr (y kw whd ). ovcu

pcv dvc uch u d ccu bk

y kd wh iup r (ir) ap

iup Cpcy (aiC).

B wh h 2005 d h neC, ac 409

qu idu C P (iCP) h c pwc cp, pup, , dv , -

cd u, v h c, h d,

d h b cp h c pw

uz qup hv sCCr cy kd

b. th b w d pc cp

u cu ud h cy wh h p

dd b d, h sCCr h c p

z p hzd du cc

c.

a dd cc pw cu c d

uy cp upd h qup y

uppy, vb u cu wh du c c

c dcy. i h vb u cu hqup xcd h sCCr h p, h u c b

cphc.

th du d c ccp by

qup ucu d h sCCr h h

up cpcy up h ccu

pc dvc h sCCr h p whch

d. th pcc c c u cd

d cu wh h p c b ud y.

F xp, b h duc neC ac 409,

p hd d ccu pcv dvc wh

up 22 ka, ucu

uppvd p w b h p wh sCCr

22 ka. Hwv, ch pw cp wh h ph d sh Ccu Cu r iup

r, whch ky b 5ka i 22 ka

u w ccu, h ccu pcv dvc y

b b y up h u, bu h

pw cp wh h p cud vy xpd

cch .

B 2005, h neC ddd h pb wh

h dv qud b qup h cy

h qup’ sCCr ccd ppvd hd.

th neC pccy qu sCCr k :



3© 2009 Litteluse • POWR-GARD® Products


idu c p [ac 409]•

idu chy cc p [ac 670]•

mup HVaC qup [ac 440]•

m dcc wch [ac 230]•

mup c [ac 430]•

ahuh sCCr k d b qud by v

neC ac, w w x hw d h sCCr

idu C P ccd neC ac 409.

th neC h ddd sCCr b qu c

d hp ucu, w, d

osHa d nFPa y u dqu. m pccy, ac 409 qu y

p d c p cc hzd

bh wk v. sCCr k

pcy p wh du c p

vd c h, wh vb

u cu cd by c uy cp

by ch wh cy. F y d by,

cp ccu sCCr k qup

wh vb u cu u b u

h h qup b, u, d wk

pcd p hzd.

Overcurret Protective Device Iterruptig Ratig

iup r (ir), d ap

iup Cpcy (aiC), h xu u cu h

ccu pcv dvc uch u d ccu bk

y b qud y p (up). ahuh h

dc h wy u d ccu bk d,

h iup r iup Cpcy u

ccu bk h sCCr.

ac 110.9 h neC qu vcu pcv

dvc hv up uc h vb

u cu d v h qup dd

pc. ac 110.10 h neC pccy qu h

vcu pcv dvc d h cp hy

dd pc cdd h xcvd d ccu y cp ccu h

v h ccu u.

Fu d ccu bk h ld rczd by

nrtl d ud by cd d vd

y up c u cu. i d b

ppv, u u p y d d

yh ud , v h h cud

fb uud. Ccu bk u p

y ud cd cd d d yh

by cu cch . Ccu bk hwv,y v hh pu d c b uc

hzdu . i p kp d

h ccu bk uppy pc

d d ppvd y up hh v h

ccu cu y . a up h ccu

h up , ccu bk y

pb ppvd uh u. awy

chck wh h vcu pcv dvc ucu

d wh Ul h ppcb y cy h

vy h xu up cu d yp

vcu pcv dvc b cdd u.

How do you determie the SCCR o a Idustrial

Cotrol Pael?

neC ac 409.110 h h sh Ccu Cu

r du c p bd h

h sh Ccu Cu r ld d lbd

by, by uz ppvd hd. Ul 508a

supp sB v xp ppvd

hd. oh ppvd hd h dc

h c cc pc d y vv pd

d y by cd p h

c judc wh h p d.

sub p Ul h nrtl b d

d ld y b h pd hd

qup ucu h ucu h p pcc ppc d , wh

h p p pc qup whch

ld. ah ub p ppv

y b b hh sh Ccu Cu r h

h ppvd hd c pvd.

th Ul 508a supp sB hd h sCCr

du c p d qu h p b

ld. supp sB dcb hw h sCCr

p bd h h dvdu pw

cp d yp cu- pw dvc

ud wh h p. sc 2006, ucu cu

c p h cd by Ul ppy h Ul l

k u w h cuc dd d k

qu Ul 508a supp sB.

mucu wh bud y w cu

p , ucu p h hv v

p cu y p u h Ul 508a

supp sB hd bh h sCCr h

p neC ac 409 qu. th Ul 508a

supp sB hd, hwv, y pvd

dqu sCCr h ppc. i h u, h

p u b -d ld d ppvd by

h hd.





Wh p wh u d ccu bk ld by nrtl wh hh u sCCr, h qup uc d

b u dc h vcu pcv dvc u

b pcd y by pcd u c d , by

pcc k, d, d ccu bk.

P h ld w b cuzd by h c

cc pc (aHJ) h qud neC 409 sCCr

k. i qud by h c aHJ, ucu u

kp dd cd h b , sCCr

cp, d h hd ud d h v

sCCr h p.

What is Curret Limitatio, ad How Does Curret

Limitatio icrease Short Circuit Curret Ratigs?ac 240.2 h neC h cu- dvc

h duc h pk -hu cu vu

uby h h p pk cu h wud

C

U R R E N

T

TIME

NOTE:

Total Clearing I2 t =

Melting I2 t + Arcing I2 t

Fault Occurs

Arc is Extinguished

Peak Let-Thru / Current (lpeak)Fuse Elements Melt

Arcing Energy (l2 t)

Maximum Possible Peak Current

if no fuse or a non current-limiting fuse is used.

(Peak value can be as high as 2.3 times the

available RMS fault current.)

Melting Energy (l2 t)

Melting

Time

Arcing

Time

Fuse Total Clearing Time

(less than ½ cycle)

Figure 1

ccu h cu- dvc w ud. Wh hdvc p cu- , p d

c h u h ½ aC cyc (0.0083 c.).

s Fu 1.

Fu 1 hw h xu u pk cu

du h ½ cyc u. Dpd

h pw c d wh h u ccu, h xu

pb u pk cu (ipk) whu cu

c b hh 2.3 h vb rms

u cu wh h u ccu. a hw, cu-

u ud, h xu u pk

cu d c h pk cu h

cud pby fw h u w ud. th cu-

u k d c h u h 0.0083

cd. th ud h cuv kw h i² -

huh y h u. th w h i² , h w h

ducv h y h p huh h ccu

wh upd.





RMS vs. Ipea

i p p u h h sCCr cp

p xpd rms ka d u

pk cu (ipk). rms (r-m-squd) cu

xp cv cu v pd . a

dcud bv, h ccu ccu, h u

pk cu c ch 2.3 h vb rms cu

h p h u. i h wd, h vb rms

h ccu cu w 10 ka, h ipk cud b 23 ka.

Cvy, h ipk cu- u 23 ka, h

quv pp rms vu 0.435 h ipk,

10 ka. Wh ppy ppd, cu- u w

h ipk d pp rms h ccu cu v h

h h p c y hd. th c cu-

u duc h pp rms u cu

ud d h sCCr du c

p. i ccpb h c aHJ, h hd y b

ud pc Ul 508a tb sB4.2 d u

bh h sCCr c du c p.

Curret Limitatio ad Pea Let-through ChartsCu- u p h cu-

w h xu u pk cu

vu uby h h pk cu h cud

fw h u w h ccu. Fu 2 hw h

hp bw h vb yc rms u

cu (hz x) d h xu u pk

cu (ipk) (vc x) pb h ccu ccu.

l a-B p h xu pb u

pk cu ud w-c cd (15% pw c,

yc), 2.3 h vb yc rms

u cu. th h Fu 2 p h c

vu p ypc cu- u.

F xp, h vb yc rms u cu

(hz x) h d c p

w 100ka, h xu u pk cu

pb whu cu wud b 233,000 p

( a-B). Hwv, 200 ap cu- u

w ud, h xu u pk cu (ipk)

wud b d ppxy 20,000 p. i 30

p u w ud, h xu u pk

cu (ipk) wud b d ppxy 6000 p.

600

400

200

10060

30

100

1000000

200000233000300000400000

600000800000

100000

20000

30000

40000

6000080000

10000

2000

3000

4000

60008000

1000

200

300

400

600800

1 0 0

2 0 0

3 0 0

4 0 0

6 0 0

8 0 0

1 0 0 0

2 0 0 0

3 0 0 0

4 0 0 0

6 0 0 0

8 0 0 0

1 0 0 0 0

2 0 0 0 0

3 0 0 0 0

4 0 0 0 0

6 0 0 0 0

8 0 0 0 0

1 0 0 0 0 0

2 0 0 0 0 0

A

B

Available Fault Current Symmetrical R.M.S. Amperes

P e a k L e t - t h r u I n A m p e r e s

FuseAmpereRating

Figure 2

100

1000000

200000

300000

400000

600000800000

100000

20000

30000

40000

6000080000

10000

2000

3000

4000

60008000

1000

200

300

400

600800

1 0 0

2 0 0

3 0 0

4 0 0

6 0 0

8 0 0

1 0 0 0

2 0 0 0

3 0 0 0

4 0 0 0

6 0 0 0

8 0 0 0

1 0 0 0 0

1 8 0 0 0

2 0 0 0 0

3 0 0 0 0

4 0 0 0 0

6 0 0 0 0

8 0 0 0 0

1 0 0 0 0 0

2 0 0 0 0 0

600

400

200

10060

30

A

B

D A

BC


P e

a k L e t - t h r u I n A m p e r e s

FuseAmpereRating

Figure 3





Fusible SwitchSCCR=200kAw/ Class J Fuses

Compressor Condenser Fan Compressor

Feeder Circuit

Branch 3Branch 2Branch 1

(3) 60A, Class J fuses

MCCBIR=14kA

IEC StarterSCCR=50kA


(3) 15AClass CC

Fuses

Fusible SwitchSCCR=200kA

w/ Class CC Fuses

9A Cont.Marked

SCCR=5kA

1500 VA CPT460/120VAC

Power Distribution Block(Unmarked)

480VAC 3∅ 60HZ

1.5 HP 15 HP10 HP

(2) 8A, Class CC fuses

Figure 4

Tested MethodFu 3 hw hw h pk -hu ch c b ud

h quv pp yc rms

u cu h y c whd. F xp,

h vb yc rms u cu h d

600 ap cu- u w 100

ka (P a), h u p wh h ½ cyc d

h xu u pk cu

h 45 ka (P B). a u pk cu (ipk)

45 ka (P B) h xu u pk

cu (P C) h 18 ka rms cu c

(P D). i h wd, h cu vb u cu

100 ka, 600 ap cu- u w h

ipk quv vb rms cu 18 ka. sc

h hh pb quv rms u cu 18 ka,

cp wh h u wh sCCr 18 ka

hh w b y pcd, k h cb

cpb uvv up p 100 ka u.

Usig pea let-thru charts to estimate the SCCR oidustrial cotrol paels

B yu ub yu du c p Ul

h nrtl ppv , yu c u h “td

mhd” h xu ppcv rms u

cu, sCCr, h h p w y hd. l’

x xp ypc du c p. s

Fu 4.

i h xp, h p b d cy wh

h vb rms u cu 60,000 ap 480

VaC. th d ccu h p c

ub dcc wch wh h lu JtD_iD 60

ap Ul C J u. th d sCCr cp

h p h b dd b 10 ka. th,h qu w d w : i ppcv 60 ka

yc rms u ccu, w h 60 ap JtD_iD

u h pp rms yc -huh cu





FuseAmpereRating

600

400

200

100

60

30

100

1000000

200000233000300000400000

600000800000

100000

20000

30000

40000

6000080000

10000

2000

3000

4000600074008000

1000

200

300

400

600800

1 0 0

2 0 0

3 0 0

4 0 0

6 0 0

8 0 0

1 0 0 0

2 0 0 0

3 0 0 0

3 2 0 0

4 0 0 0

6 0 0 0

8 0 0 0

1 0 0 0 0

2 0 0 0 0

3 0 0 0 0

4 0 0 0 0

6 0 0 0 0

8 0 0 0 0

1 0 0 0 0 0

2 0 0 0 0 0

A

B


P e a k L e t - t h r u I n A m p e r e s

Figure 5: peak let-thru curve For littelFuse

jtd_id class j Fuses

10 ka ? l’ k k h pk -huh cuv h y JtD_iD u.

U h Pk l-thu Cuv (F.5), w h

ppcv vb yc rms u cu

60,000 ap, h 60a C J u h xu

u pk cu (ipk) ppxy 7400

ap. mv hzy v h xu

u pk cu d dwwd bck h

ppcv vb rms yc u , w h

h pp rms yc u cu ppxy

3200 ap.

sc h 60 ap C J u h xu

quv rms u cu vb h h

cp h p, c y pc y cp wh h h sCCr h 3200 ap

ppcv rms yc u cu 60,000

ap wud ccu.

Hwv, h ccu bk u bch

ccu h wh h cu- u, uch

hw Fu 4, c u b k u h h

hhd cu h cu- d u

h h up y cu-

bch ccu vcu dvc. i h bv xp,

h hhd cu h 60 ap C J u

ppxy 1000 ap, w bw h up

h 14ka ccu bk Bch Ccu n. 1.

th, d d ld by nrtl, h sCCr

h p cud b 60,000 ap wh u

60 ap lu JtD_iD C J u. i c, h

ppcv vb yc rms u cu w

200 ka, h u wud h pp rms u cu

y 4000 ap, y pc cp

wh h p.

Usig the UL 508A Supplemet SB method to

determie the SCCR o idustrial cotrol paels

mucu du c p h cd

by Ul x h Ul b h qup u w

h cuc dd d qu Ul sdd508a. sc 2006, h sCCr b qu Ul

508a supp sB dy. ahuh h dd

ld du c p, h qu

d hd Ul 508a supp sB c b ppd

y c p h c d pvd pw

yp uz qup.

a d pvuy, Ul 508a supp sB pvd

hd h sCCr du c p

bd h yp vcu pcv dvc d h

cp ud wh h p. accd

supp sB, h sCCr du c p qu h sCCr :

th w d cp, •

th w d Ul ppvd d•

cb,

th sCCr ppvd cb•

ccd h dd.

F h qup wh cc

dbu y cy u b d hd

w-c c cpy pc pp d

qup, vy cp wh du c

p u b dd p w-c

c.

Ul 508a supp sB cuy d uz h

pp rms -huh cu cu- v

cu pcv dvc bh h sCCr du

c p. i cp h Ul xu wb

u pk huh cu (ipk) du h

½ cyc cu- u wh h rms sCCr h

vu cp ud wh h p.

Ul 508a supp sB4.1 dcb h p

bh h sCCr du c p:





Step 1D h sCCr dvdu pw cp

cud Ul cd d ppvd d

cb.

Step 2

mdy h sCCr c cp cb

cu- u ud h d ccu.

Step 3

appy h w d sCCr y pw cp,

vcu pcv dvc, dd cb

h sCCr h p.

i d udd ch p d bv, u k xp ypc du c p d cp

ch p ccd h dd.

Pael EampleU Ul 508a supp sB d h p d bv,

d h sCCr h p hw Fu 6.

Step1

D h sCCr dvdu pw cp

cud Ul cd d ppvd d

cb.

th p bh h sCCr h c p

by d d cd h sCCr h

dvdu pw cp d Ul cd d ppvd

cb wh h p. a pw cp h

ud c d dbu pw dvdu ,

dv, d h d ud d h cu ub yzd. Pph uch cu u

d h cdy d cu

Figure 6

Fusible SwitchSCCR=200kAw/ Class J Fuses


Feeder Circuit



MCCBIR=14kA



(3) 15AClass CC

Fuses

Fusible SwitchSCCR=200kA

w/ Class CC Fuses

9A Cont.Marked

SCCR=5kA

1500 VA CPT460/120VAC

Power Distribution Block(Unmarked)

480VAC 3∅ 60HZ

1.5 HP 15 HP10 HP






d c pw cud puh bud cc c h h dc pw ccu

ph, d hv b yzd.

m pw cp uch u, ccu bk,

wch, cc, vd y, d c

kd wh up sCCr. s

y b kd, bu h ucu y pubh

h h ccu cu h u h

p uc. F h h kd

wh sCCr pcd by h ucu, tb

sB4.12 ( Fu 7) Ul 508a supp sB pvd

ud xu h ccu cu h dvc.

a pw cp wh h p u b dcud

d h h ccu cu cdd.

i h xp hw Fu 6, pw cp h pw d ccu d bch ccu kd

wh sCCr iup r xcp h pw

dbu bck h dbu h pw wh h

p. accd Ul 508a supp sB, h du

h ccu cu ukd bck pw

dbu bck 10 ka (s tb sB4.1).

a cd h sCCr ch pw cp h

p d sCCr ukd cp

tb sB4.1, pp h h cc Bch

Ccu #2 wh kd sCCr 5 ka h w d

sCCr h p. Hwv, c cb pw

cp wh vcu pcv dvc, uch

c wh cu- u y b Ul

Compoet Short circuit curret ratig, A

Bu b 10

Ccu bk (cud gFCi yp) 5

Cu a

Cu hu 10

Fuhd 10

idu c qup:

. auxy dvc (vd y) 5b. swch (h h cuy ub yp) 5

c. mcuy ub wch

rd v 60 p v 250 v 5

rd 250 v , 60 p , d v 2kVa 3.5

rd 250 v d 2 kVa 1

m c, d hpw (kW)

. 0 - 50 (0 - 37.3) 5 c

b. 51 - 200 (38 - 149) 10 c

c. 201 - 400 (150 - 298) 18 c

d. 401 - 600 (299 - 447) 30 c

. 601 - 900 (448 - 671) 42 c

. 901 - 1500 (672 - 1193) 85 c

m sck b 10

mu cu u 10 b

rcpc (gFCi yp) 2

rcpc (h h gFCi yp) 10

suppy pc 0.2

swch u 5

t bck pw dbu bck 10

a A short circuit current rating is not required when connected via a current transormer or current shunt. A directly connected current meter shall have a marked shortcircuit current rating.

b The use o a miniature use is limited to 125-volt circuits.c Standard ault current rating or motor controller rated within specifed horsepower range.

Figure 7: TABLE SB4.1.2 ASSUMED MAxIMUM SHORT CIRCUIT CURREnT RATInG fOR UnMARkED COMPOnEnTS





cd d ppvd wh d sCCr h hhh h w d sCCr y dvdu cp.

i y cb wh h c p Ul cd

d ld uch, h h sCCr h ppvd

cb c b cdd wh bh h wk

k bch ccu. i h xp, cu wh

h ucu h cc ud Bch Ccu #2

d wh Ul dcu, w h wh h

cc pcd by Ul C CC Ul C J

u, Ul ppvd “yp 2” cd wh

d sCCr 100 ka. th cb y

c h sCCr h bch ccu, bu pvd

h uc h h cc w pb

h ccu. awy cu h qup ucu

vy Ul ppvd cb h ccu cu d pc ccuc h c c h sCCr

yu p.

i w w k u p d Fu 6 d ddh sCCr ch cp, ppvd cb,

d d d bch ccu, wud k h k

Fu 8:

a h cp sp 1:

th sCCr h Fd Ccu 200 ka•

th u sCCr Bch Ccu #1 •

14 ka du h ir h mCCB

th sCCr Bch Ccu #2 100 ka bcu •

h ppvd cb .


50 ka du h ieC .

th w d sCCr h p h pw•

dbu bck, wh sCCr 10 ka

tb sB4.1

Fusible Switch

SCCR=200kA

w/ Class J Fuses


Feeder Circuit



MCCB

IR=14kA

IEC Starter

SCCR=50kA

IEC Starter

SCCR=50kA

(3) 15A

Class CC

Fuses

Fusible Switch

SCCR=200kA

w/ Class CC Fuses

9A Cont.

Marked

SCCR=5kA

1500 VA CPT

460/120VAC

Power Distribution Block

(Unmarked)


480VAC 3∅ 60HZ

1.5 HP 15 HP10 HP

200 kA

10 kA

14 kA 100 kA 50 kA

Figure 8





Step 2 mdy h sCCr c cp cb

cu- u ud h d ccu.

Ul 508a supp sB ac sB4.3 dcb hw d

cp uch cu- u c h pk

-huh cu wh h p. tb sB4.2² Ul 508a

supp sB (s Fu 9) h Ul xu

wb u pk huh cu (ipk), d

h xu wb c i² Ul C cu-

u d v ppcv vb rms

u cu (50 ka, 100 ka, 200 ka). a ucu

Ul ppvd cu- u u h ipk d

i² h xu vu hw h b. Ul 508a

supp sB u h ipk vu d tb sB4.2 d h u’ by h pk -huh

cu bch ccu wh h p.

t d h sCCr cb wh h

p, Ul 508a ac sB 4.3.3 h h ipk h

d u h qu h w d sCCr

y pv cp bch ccu, h h sCCr

h cb h vb rms cu whch h

u h pk cu. th w xp hud

hp xp h.

Fu 8 hw h h Pw Dbu Bck wh

ud sCCr 10 ka dcy wh h Ul

C J cu- d ccu u d 60 p.

tb sB4.2 hw h h xu wb ipk h60 p C J u vb rms u cu

200 ka 16 ka. th vu xcd h sCCr h pw

dbu bck (10 ka). Hwv, tb sB4.2 hw

h h xu wb ipk h u

vb rms u cu 100 ka 10 ka, whch

h qu h pw dbu bck sCCr 10 ka.

th, h sCCr h cb 100ka.

th pc y b pd wh pw cp

bch ccu d h cu- u

y c h sCCr h cb.

i p p u h sp 2 dc ppyy cu- dvc h d ccu wh

pv (-vcu pcv) dvc bch

ccu. i h xp, bd tb sB4.2, h 60

ap Ul C J u h d ccu b

h ipk 10 ka h vb u cu w

100 ka. i h vcu pcv dvc bch

ccu d h vb u cu h 100 ka,

bu h h up h bch ccu

vcu pcv dvc, h bch ccu vcu

dvc y b p b h d u c h

ccu, pby cu hzdu u. th,

h sCCr h p c b h h w

iup r y u ccu bk h p,

u h b d d d by nrtl.

a p sp 2, w w hv h cu

ud Fu 10:

th sCCr h Fd Ccu d pw dbu•

bck 100 ka


14 ka du h mCCB

th sCCr Bch Ccu #2 100 ka•


50 ka du h ieC

i p h py, Ul 508a tb sB4.2

d h Ul xu wb u pk huh cu Ul u cu , uch

C J u d h 30 ap, 600 v C

t u h 800 ap. i h x d

Ul 508a, Ul y dd h u vu tb sB4.2

pby w h u ucu’ pubhd pk

huh cuv d h ipk pcc u yp

d . P cc Ul h d

Ul 508a supp sB d u vu hw

Fu 9.





fusetypes

fuseratig

amps

Betwee thresholdad 50 A

100 A 200 A

I²t 10³ lp 10³ I²t 10³ lp 10³ I²t 10³ lp 10³C CC 15 2 3 2 3 3 4

20 2 3 3 4 3 5

30 7 6 7 7.5 7 12

g g 15 - - 3.8 4 - -

20 - - 5 5 - -

30 - - 7 7 - -

60 - - 25 10.5 - -

300 V

C t

30 3.5 5 3.5 7 3.5 9

60 15 7 15 9 15 12

100 40 9 40 12 40 12200 150 13 150 16 150 20

400 500 22 550 28 550 35

600 1000 29 1000 37 1000 46

800 1500 37 1500 50 1500 65

1200 3500 50 3500 65 4000 80

C J

d 600 V

C t

30 7 6 7 7.5 7 12

60 30 8 30 10 30 16

100 60 12 80 14 80 20

200 200 16 300 20 300 30

400 1000 25 1100 30 1100 45

600 2500 35 2500 45 2500 70

800* 4000* 50* 4000* 55* 4000* 75*

C l 800 10000 80 10000 80 10000 80

1200 12000 80 12000 80 15000 120

1600 22000 100 22000 100 30000 150

2000 35000 110 35000 120 40000 165

2500 - - 75000 165 75000 180

3000 - - 100000 175 100000 200

4000 - - 150000 220 150000 250

5000 - - 350000 - 350000 300

6000 - - 350000 - 500000 350

C r RK1 RK5 RK1 RK5 RK1 RK5 RK1 RK5 RK1 RK5 RK1 RK5

30 10 50 6 11 10 50 10 11 11 50 12 14

60 200 200 10 20 40 200 12 21 50 200 16 26

100 500 500 14 22 100 500 16 25 100 500 20 32

200 1600 1600 18 32 400 1600 22 40 400 2000 30 50

400 5000 5000 33 50 1200 5000 35 60 1600 6000 50 75

600 10000 10000 43 65 3000 10000 50 80 4000 12000 70 100

* Value applies to Class T uses.

Figure 9: TAbLE Sb4.22 - UL MAxIMUM ALLOwAbLE Ip

and pEAK LET-ThROUGh CURRENT I2t, FOR CURRENT-LIMITING FUSES

AT 600 VAC





Cotrol circuit overcurret protectioUl 508a ac sB3.2 qu bch ccu vcu

pc c ccu h ppd h d

ccu hw Fu 6. Fuh, h iup

r h bch ccu u ccu bk u b

qu h h v sCCr h p. i h

xp v bv, h 8 ap c ccu u

bch ccu Ul C CC u wh kd ir 200 ka,

cpy wh h qu. i p b

h uppy u uppy pc

wd h py d c ccu. th sCCr

h p c b h h ir h bch

ccu d c ccu u ccu bk.

Step 3 appy h w d sCCr y pw cp,

dd by sp 2 vcu pcv dvc,

dd cb h sCCr h p.

i u xp, dy h sCCr c

cb bd h ipk h cu- d

u, h sCCr h p bd h w d

sCCr y pw cp dd by sp 2, h

w d sCCr y bch ccu, h w d

iup r y vcu pcv dvc.

sc Bch Ccu #1 c h w d sCCr

14 ka bd h up h mdd C

Ccu Bk, h sCCr h p 14 ka.

Fu 11 hw qup b kd wh h

cpd sCCr.

Fusible Switch

SCCR=200kA

w/ Class J Fuses


Feeder Circuit



MCCB

IR=14kA

IEC Starter

SCCR=50kA

IEC Starter

SCCR=50kA

(3) 15A

Class CC

Fuses

Fusible Switch

SCCR=200kA

w/ Class CC Fuses

9A Cont.

Marked

SCCR=5kA

1500 VA CPT

460/120VAC

Power Distribution Block

(Unmarked)


480VAC 3∅ 60HZ

1.5 HP 15 HP10 HP

100 kA

14 kA 100 kA 50 kA

Figure 10





Figure 11

How to icrease the SCCR o idustrial

cotrol paels

i h xp bv, w h c ppy d

cp d pcv dvc c c h sCCr

yu by. th v h h yu c d

c h sCCr d by yu du c

p wh c h y cc wk.

U cp ppvd cb wh•

hh sCCr.

U cu- u h cu-•

cp h d ccu ( Ul 508a

supp sB ).

U vcu pcv dvc wh hh•

up bch d c ccu.

sub h p Ul h nrtl ppv•

uz h “td mhd.”

l u k Fu 6. o y wy c h

sCCr h p wud b pc h 14 ka mCCB

Bch Ccu #1 wh ub dcc wch.

F xp, pc h mCCB wh lu yplFFs030CC dcc wch d lu C CC u

wud c h u sCCr Bch Ccu #1

50 ka. th, h sCCr h p wud b

cd 50 ka.

i p kp d h Ul 508a supp

sB xu sCCr y 200 p

ukd uppy pc ( Fu 7). Ul 508a

ac sB3.2 d w uppy pc h

py c ccu. i y uppy pc

ud bch ccu, py pc h uppy

pc wh l u Ul C CC u uchDin ud uhd c dcy c h

sCCr du c p d c y.

lu, ic. h ucd h lD d ls Pw

Dbu Bck d spc Bck w Ul ld wh

hh sCCr wh ud wh cu- u h c

c h sCCr yu du c p.

P u sCCr C wb

www.litteluse.com/SCCR .

Summary

a du c p u b kd wh•

sCCr.

P c b ubd d d by nrtl •

bh h sCCr.

Ul 508a supp sB y b ud bh•

h sCCr.

U cu- u h b d •

wy c h sCCr yu p.

Cu- u c y d by.•

i p b h p Ul ld d

lbd, Ul 508a supp sB ud bh

h hh u sCCr h p, cp d u b dd d dcud. i d h

kd sCCr, w b d uc u cy

dc h qu pc vcu pcv

dvc y wh h pcc cp y

dd u h ppc.

Fw neC d Ul 508a dd d u w

u ucu d u h h y

d c cd d dd, hhy

b, d wk u d .

lu, ic. cp cu- u

d cc c h sCCr du c

p d duc ac-Fh d h cc hzd cc wk. lu PoWr-garD svc

pvd sCCr cu vc, ac-Fh Hzd

a, d y pduc h hp ucu,

bud w d ppcb osHa

d nFPa y u d ud.

F bu neC 409, Ul 508a d pduc

h c hp c h sCCr d y yu du

c p, p cc lu ecc Pduc

tchc supp 800-TEC-fUSE, v u

www.litteluse.com/SCCR





Edotes

1 National Electrical Code®

and NEC®

are registered trademarks o the NationalFire Protection Association, Quincy, MA

2 With the permission o Underwr iters Laboratories, Inc., material is reproducedrom UL Standard 508 A, Standard For Industrial Control Panels, which iscopyrighted by Underwriters Laboratories, Inc., 333 Pfngsten Road, NorthbrookIllinois 60062. UL shall not be responsible to anyone or the use o or relianceupon a UL Standard by anyone. UL shall not incur any obligation or liability ordamages, including consequential damages, arising out o or in connectionwith the use, interpretation o, or reliance upon a UL Standard. UL’s Standardsor Saety are copyrighted by UL. Neither a printed copy o a Standard, nor thefle or an electronic version o a Standard may be copied, reproduced, and/oraltered in any way. All o UL’s Standards and all copyrights, ownerships, andrights regarding those Standards shall remain the sole and exclusive propertyo UL.

Revisions o UL Standards or Saety are issued rom time to time. A ULStandard or Saety is current only i it incorporates the most recently adopted

revisions. Copies o the current edition o UL 508A may be purchased rom:

comm 2000

1418 Brook Drive

Downers Grove, IL 60515 USA

1-888-853-35 03 in U.S. and Canada or

415-352-2168, outside the U.S. and Canada

Fax: 1-888-85 3-3512 in U.S. and Canada

Fax: 1-630-93 2-7387 outside the U.S. and Canada

http://www.comm-2000.com



Form no. PF992-C

© 2009, lu ic.

spcc dcp d uv h u ccu kw h pubc, bu ubjc ch whu c. V www.u.c h up--d chc .

Littelfuse, Inc.Cicago Illinios

www.litteluse.com/SCCR

1-800-TEC-fUSE (1-800-832-3873)

Documents

UsingFusestoIncreaseSCCR.pdf