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2.8.3
Operate and Reset Time
Attribute
Starter operate time (³ 2xIs)
char = IEC-NI,
t
Operate time
op
char = ANSI-MI,
char = DTL
ANSI DECAYING
Reset time
IEC DECAYING
t
res
Repeatability
Overshoot time
Disengaging time
Figure 2.7.3-1 and Figure 2.7.3-4 show the operate and reset curves for the four IEC IDMTL curves with a time
multiplier of 1.
Figure 2.7.3-2 and Figure 2.7.3-3 show the ANSI operate and reset curves. These operate times apply to non-
directional characteristics. Where directional control is applied then the directional element operate time should be
added to give total maximum operating time.
Unrestricted ©2018 Siemens Protection Devices Limited
Value
20 ms, ± 20 ms
K
=
t
[ ]
a
op
I
Is
IEC-VI,
for char =
IEC-EI,
IEC-LTI
é
ê
=
t
[ ]
ê
op
I
ë
Is
ANSI-VI,
(ANSI-EI +5% -10 % absolute for I/Is>10 with TMS >2)
ANSI-EI
for char = ANSI-MI : A = 0.0515, B = 0.114, P = 0.02
, ± 1 % or ± 20 ms
t
d
R
=
t
[ ]
res
2
I
Is
for char = ANSI-MI : R = 4.85
R
=
t
[ ]
res
2
I
Is
for char =
IEC-LTI : R = 80
, ± 1 % or ± 20 ms
t
res
± 1 % or ± 20 ms
< 40 ms
< 50 ms
7SR18 Performance Specification
´
, ± 5 % or ± 30 ms,
Tm
-
1
IEC-NI : K = 0.14, a = 0.02
IEC-VI : K = 13.5, a = 1.0
IEC-EI : K = 80.0, a = 2.0
IEC-LTI : K = 120.0, a = 1.0
ù
A
ú
+
´
, ± 5 % or ± 30 ms,
B
Tm
ú
P
-
1
û
ANSI-VI : A = 19.61, B = 0.491, P = 2.0
ANSI-EI : A = 28.2,
B = 0.1217, P = 2.0
´
, ± 5 % or ± 30 ms,
Tm
-
1
ANSI-VI : R = 21.6
ANSI-EI : R = 29.1
´
, ± 5 % or ± 50 ms,
Tm
-
1
IEC-NI : R = 9.7
IEC-VI : R = 43.2
IEC-EI : R = 58.2
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