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Trip Time
Characteristics As
Per ANSI
Tolerances
Influencing
Variables for
Pickup
7UM62 Manual
C53000-G1176-C149-3
As per ANSI/IEEE (see also Figures 4-2 and 4-3)
VERY INVERSE
INVERSE
MODERATELY INV.
EXTREMELY INVERSE
DEFINITE INVERSE
≥ 20 are identical to those for I/I
The trip times for I/I
p
Pickup Threshold
Dropout Threshold
Pickup Currents I
p
Voltage Threshold U<
Trip Time for 2 ≤ I/I
≤ 20
p
Power Supply Direct Voltage in Range
0.8 ≤ U
/ U
PS
PS nominal
Temperature in Range
23 °F ≤ ϑ
≤ 131 °F
amb
–5 °C ≤ ϑ
≤ 55 °C
amb
Frequency in Range
0.95 ≤ f/f
≤ 1.05
N
1
) For I
= 1 A, divide all limits and increments by 5.
N
4.3 Inverse-Time Overcurrent Protection (ANSI 51, 67)
t
=
t
=
t
=
t
=
t
=
For all Characteristics
t
D
I
I
p
Approx. 1.10 · I
Approx. 1.05 · I
corresponds to approx. [0.95 · pickup
threshold]
1 % of setting value, or 50 mA
1 % of setting value, or 0.5 V
5 % of reference (calculated) value + 1 %
current tolerance, respectively 40 ms
≤ 1.15
1 %
0.3 % / 10 °F
0.5 % / 10 K
< 1 %
æ
ö
3.922
⋅
ç
÷
-------------------------- -
+
0.0982
2
è
ø
(
⁄
)
I I
–
1
p
æ
8.9341
ç
-------------------------------------- -
0.17966
+
2.0938
è
(
⁄
)
I I
1
–
p
æ
0.0103
ç
--------------------------------- -
0.0228
+
0.02
è
(
⁄
)
I I
1
–
p
æ
ö
5.64
ç
÷
-------------------------- -
+
0.02434
2
è
ø
(
⁄
)
I I
1
–
p
æ
0.4797
ç
-------------------------------------- -
0.21359
+
è
1.5625
(
⁄
)
I I
1
–
p
= Trip time in seconds
= Setting value of the time multiplier
= Fault Current
= Setting value of the pickup current
= 20.
p
p
≥ 0.3
for I
/I
p
p
N
[s]
D
ö
⋅
÷
[s]
D
ø
ö
⋅
÷
[s]
D
ø
⋅
[s]
D
ö
⋅
÷
[s]
D
ø
1
)
409
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