GEK-34054
If t he t r ipping c u r r e nt e xceeds 30 a mpe r e s , a n a uxilia r y r e lay
s hould be u s e d, t he connec t ions being s uc h that t he t r ipping c u r r en t
doe s not pas s t hr oug h t he conta cts o f the ta r g e t a n d s ea l-in coils o f
the pr ote c ti ve r e lay.
CONTACTS
The c ur r en t -c losing r a t ing of t he conta c ts is
3 0
a mpe r e s f o r
vol t ages n o t e xceeding 2 50 volt s .
The cu r r e nt-ca r r y ing r a t ing is
limite d by t he r a ting s of the s eal-in unit.
BURDENS
Bur de n s for the t ime-ove r c u r r en t unit a r e g ive n in Table IX.
TABLE IX
VA AT 5 AMPS
RANGE
HZ
MIN.
BURDENS AT MIN.
BURDENS IN
CALCULATED FROM
{AMPS)
TAP
PICKUP
OHMS (Z}
IMPEDANCE AT MIN.
TIMES PICKUP
PICKUP (I2Z)
R
z
3
10
20. 0
0.5 - 0. 4
60
0.5
0.40
3.90 4. 15
4.20 2.90 2. 20
104. 0
1.5 -12.0
60
1.5
0.23
0.53 0.58
0.58 0. 36 0.28
14. 5
2.0 -16. 0
60
2. 0
0.14
0. 30 0.33
0.34 0.22 0.15
8. 25
0.5 - 4.0
50
0.5
1.16
3. 25 3.45
3. 45 2. 41 1. 82
86. 25
1. 5 -12.0
50
1. 5
0.19
0. 44 0.48
0.48 0. 298 0. 23
12. 00
2.0 -16.0
50
2.0
0. 116 0.25 0.27
0.27 0.180 0. 12
6. 75
NOTE:
The impe dance values g iven a r e those f o r t he minimum
t a p of each r e lay.
The impe da nce f o r o t he r taps a t
pic k-up
c u r r e n t
(TAP
R AT ING )
va r ie s
i n ve r s e l y
( appr oxima t e ly ) a s the s qua r e of t he t a p r a t ing.
Fo r
e xa mple , for a r e lay with 0 . 5 -
4. 0 amp r a nge, t he
impe dance of the 0 . 5 a mp tap is g iven as 4. 15 o hms .
The impedance of the 2 . 0 amp tap a t 2 . 0 a mpe r es is
( . 5/2 ) 2
X
4. 15 - 0 . 2 6 .
8
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