Calculation RED670 7SA R2

CT's calculation for cable line bay 33kV  R B   RCond .  R Prot.

 RCond .   R N  

 R B : connected burden  RCond . : conductor  burden

2  l 

l  : conductor length

    q

q : conductor  cross - section     1      : specific resistence

 P  N  2

 I  N 

 RCT  : internal CT burden

Vk min   K td  

 I  scc _ max

1.3  I  pn

 R N  : nominal burden

 ( RCt    R B )  I  sn

V kp : kneepoint

voltage

 K td  : trasient dimensioni ng factor 

For ABB  I  pn : CT rated primary current  Eal    Ealreq   I  K  ma x 

 I  sn  I  pn

 Eal    Ealreq   I t  ma x  2 

  0.25    R Ct    R L  2    I r     

 I  sn  I  pn

 I  sn : CT rated secundary current  I  ssc _ ma x : symmetrica l short - circuit current

  0.25    RCt    R L  2    I r     

ICC CT

CORE

CLASS

Current ratio xxx/1A 1500

1

Caculated: F. GÓMEZ Reviewed: W. CASTAÑEDA  Approved: M. ROSETY

PX

R Cond. (Ohm)

R Prot./ (Ohm)

RB (Ohm)

Vkp

 

I''cc (kA)

Ktd

Vk min

Ptot

 

Request:

>25%BURDE >25%BURDEN N

Vkp > Vk min

50

4.0

0.45

0.250

0. 0.70   1300.00

40.00

319.81

0.70

-o-

2.80

50

4.0

0.45

0.250

0. 0.70   650.00

40.00

349.64

0.70

-o-

  RED670  

6.50

50

4.0

0.45

0.250

0. 0.70   1300.00

10.00

479.76

OK

3.50

50

4.0

0.45

0.250

0. 0.70   650.00

10.00

559.52

OK

  7SA  

6.50

50

4.0

0.45

0.050

0. 0.50   975.00

31.50

1.00

282.55

0.50

-o-

OK

300

3.50

50

4.0

0.45

0.050

0. 0.50   650.00

31.50

1.00

322.79

0.50

-o-

OK

600 300

  7SA  

3.80 3.50

50 50

4.0 4.0

0.45 0.45

0.050 0.050

0. 0.50   975.00 0. 0.50   650.00

10.00 10.00

4.00 4.00

220.33 409.89

0.50 0.50

-o-o-

OK OK

300

2

#REF!

Conductor  section (mm2)

5.30

800

PX

Conductor  length (m)

  RED670  

600

2

DEVICES

R  CT BURDEN (Ohm) (VA)

600

OK OK

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