GEK-49848A
TABLE
9
B URDENS OF OV ERCU RRENT UN ITS
(
T I ME AND I NSTANTANEOUS
)
AT
60
CYCLES
Ran ge
Burdens At M i n . P i cku p
M i n . Ta p o f TOC U n i t
Burden Ohms
T im e
Charac
teri sti c
TOC
I OC
I OC U n i t
Connecti ons
U n i t
U n i t
I nver s e
2-16
V ery
1.5-
I nvers e
12
2-16
Seri es
2-8
Paral l el
4-16
R
Jx
**Z
+V A
P F
0.61 2.01 2.10 8.4 0.29
0.42 1.54 1.60 6.4 0.26
10-80
Seri es
1.58 1.65 6.6
Paral l el
20-80 0.38 1.45 1.50 6.0 0.25
2-16
S er i es
2-8
0.47 1.10 1.20 2.7 0.39
Paral l el
4-16
0.28 0.63 0.69 1.6 0.41
10-80
Ser i es
10-40 0.31 0.67 0.74 1.7 0.42
Pa ral l el
20-80 0.24 0.54 0.59 1.3 0.41
3
T imes
M i n . PU
1.27
0.76
0.81
0. 67
1.20
0.69
0. 74
0.59
2-16
S er i es
2-8
0.33 0.72 0.79 1.8 0.42
0.79
1. 5-
Extremel y
12
I nvers e
Paral l el
4-16
0.13 0.25 0.28 0.6 0.46
0.28
10-80
Seri es
10-40 0.16 0.29 0.33 0.7 0.49
0.33
Paral l el
20-80 0.10 0.16 0.19 0.4 0.53
0.19
10
T i mes
M i n . PU
0.85
0.43
+VA
At
5
Amps
53
40
41
0.34
38
0.53
30
0.47
17
0. 52
19
0. 38
15
0.70
20
0.28
7
0.33
8
0.19
5
**
The i m pedance val ues gi ven are tho s e for the mi n i mum t a p o f each rel ay. The
i m pedance for o ther ta ps, at pi ckup current
(
ta p rati n g
)
, vari es i nvers el y
a ppro x i matel y a s the squa re o f the current rati n g .
Exam pl e:
for the very
i n ve rse rel a ys,
1.5/12
amperes, wi th i m pedance of the
1.5
am pere ta p of
1.20
o hms, the i mpeda n ce o f the three - am pere t a p, a t three am pe res, i s a ppro x i matel y
(1.5/3)2
x
1.20
=
0.3
o hms .
+
Some compan i es
1
i st rel ay burdens onl y a s the vol t- am pere i n put to o perate a t
m i n i mum pi ckup .
Thi s col umn i s i n cl uded so a di rect com pa ri son c a n be made .
I t s houl d not be us ed i n cal cul ati ng vol t- am pere burden s i n a CT secondary
ci rcui t, s i n ce the burden at fi ve am peres i s used for t hi s pur pose.
*
Cal cul ated from burden a t m i ni mum pi ckup.
TAB LE
10
B URDEN OF NON-D I RE CT I ONALLY CONTROLLED I NSTANTANEOUS UNI T
Burdens a t M i n .
Burden O hms
M i n .
P i ckup
(
Ohms
)
T imes P i cku p
I ns t . U n i t
Hz Ran ge Ran ge
P i ckup
(
Amps
)
(
Amps
) (
Amps
)
R
Jx
z
3
10
20
L
6-30
6
0.110 0.078 0.135
0. 095 0.081 0.
6-150
60
H
30-150
30
o.
022 0.005 0. 023
0. 022 0. 022 0.022
10
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