I.L. 40-386.4
3-9
Similarly, three settings “T2G CV”, “T2G PkUp”, “T2G TC” must be determined to apply
ground, torque controlled overcurrent protection. Similar to any overcurrent application, the
same criteria as in a, b, and c above are used to select appropriate settings for ground, torque
controlled overcurrent protection.
The following equations can be used to calculate the trip time for all phase and ground backup
curves
T (sec) =
(for I
P
>1.5 x “T2Ø PkUp”)
T (sec) =
(for 3I0 >1.5 x “T2G PkUp”)
T (sec) =
(for 1< 3I
P
< 1.5 x “T2Ø PkUp”)
T (sec) =
(for 1 < 3I
0
< 1.5 x“T2G PkUp”)
Where:
I
PF
= Applied fault current
3I
0F
= Applied zero sequence fault current
“T2Ø PkUp”
= Phase pickup current setting (0.50 to 10.0 Amps)
“T2Ø TC”
= Phase time dial curve setting (1 to 63)
“T2G PkUp”
= Ground pickup current setting (0.50 to 10.0 Amps)
“T2G TC”
= Ground time dial curve setting (1 to 63)
T
0
, K, C, P and R are constants, and are shown in Table 3-1
Torque control of the overcurrent functions is by way of the operation of zone-2 phase and/or
ground distance logic operating. When a zone-2 distance decision is made, the overcurrent log-
ic is enabled and the curve timing begins. Operation time of the zone-2 distance (phase or
ground) decision must be added to the overcurrent trip time calculated above. Since zone-2 op-
erate time is approximately 22 milliseconds, add 22 milliseconds to the times calculated for total
trip time.
REL 301/302 offers two reset characteristics for the torque control overcurrent functions, instan-
taneous or time delayed. Instantaneous reset, as the name implies, means reset with no inten-
tional time delay. Time delay reset function is a linear characteristic shown in Figure 1 and is
intended to replicate the reset characteristics of electromechanical overcurrent relays.
T
0
K
I
P
C
–
(
)
P
-----------------------
+
T
2
φ
TC
24 000
,
---------------------
×
T
0
K
3
I
0
C
–
(
)
P
--------------------------
+
T
2
GTC
24 000
,
--------------------
×
R
I
P
1
–
(
)
------------------
T
2
φ
TC
24 000
,
---------------------
×
R
3
I
0
1
–
(
)
---------------------
GBT Curve
24 000
,
--------------------------------
×
IP
I
PF
T
2
∅
PkUp
------------------------------
=
3
I
0
3
I
0
F
T
2
G PkUp
------------------------------
=
Содержание REL 301
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Страница 24: ...I L 40 386 4 1 10 2682F39 Sheet 1 of 2 Sub 2 Figure 1 2 REL301 302 Layout Vertical ...
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Страница 55: ...I L 40 386 4 2 27 Figure 2 8 Zone 1 Extension Scheme Figure 2 7 Zone 3 Trip Logic 1503B49 Sub 2 9662A64 Sub 1 ...
Страница 67: ...I L 40 386 4 2 39 Figure 2 31 REL302 Reversible Zone 3 Phase and Ground Reverse Block Logic 1503B55 Sub 2 ...
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