4.3 Inverse-Time Overcurrent Protection (ANSI 51, 67)
407
7UM62 Manual
C53000-G1176-C149-3
4.3
Inverse-Time Overcurrent Protection (ANSI 51, 67)
Pickup and Time
Multiplier Ranges/
Resolutions
Pickup Current
51
0.50 A to 20.00 A
1
) (Increments 0.05 A)
1
)
Time Multipliers for 51
T
p
0.05 s to 3.20 s
(Increments 0.01 s)
IEC Characteristics
or
∞
(delay does not expire)
Time Multiplier for 51
D
0.50 to 15.00
(Increments 0.01)
ANSI Characteristics
or
∞
(delay does not expire)
Undervoltage Release
U<
10.0 V to 125.0 V
(Increments 0.1 V)
Trip Time
Characteristics As
Per IEC
As per IEC 60255-3, Section 3.5.2 or BS 142 (See also Figure 4-1)
The trip times for I/I
p
≥
20 are identical to those for I/I
p
= 20.
Pickup Threshold
Approx. 1.10 · I
p
Dropout Threshold
Approx. 1.05 · I
p
for I
p
/I
N
≥
0.3
Tolerances
Pickup Currents I
p
1 % of setting value, or 50 mA
1
)
Voltage Threshold U<
1 % of setting value, or 0.5 V
Trip Time for 2
≤
I/I
p
≤
20
5 % of reference (calculated) value + 1 %
current tolerance, respectively 40 ms
Influencing
Variables for
Pickup
Power Supply Direct Voltage in Range
0.8
≤
U
PS
/ U
PS nominal
≤
1.15
1 %
Temperature in Range
23 °F
≤ ϑ
amb
≤
131 °F
0.3 % / 10 °F
–5 °C
≤ ϑ
amb
≤
55 °C
0.5 % / 10 K
Frequency in Range
0.95
≤
f/f
N
≤
1.05
< 1 %
Harmonic Currents
– Up to 10 % 3rd Harmonics
< 1 %
– Up to 10 % 5th Harmonics
< 1 %
1
) For I
N
= 1 A, divide all limits and increments by 5.
t
0.14
I I
p
⁄
(
)
0.02
1
–
----------------------------------
T
p
⋅
=
NORMAL INVERSE
(Type A)
t
13.5
I I
p
⁄
(
)
1
1
–
---------------------------
T
p
⋅
=
VERY INVERSE
(Type B)
t
80
I I
p
⁄
(
)
2
1
–
---------------------------
T
p
⋅
=
EXTREMELY INV.
(Type C)
For All Characteristics
t
Trip time in seconds
T
p
Setting value of the time multiplier
I
Fault current
I
p
Setting value of the pickup current
[s]
[s]
[s]
