7SR224 Argus Performance Specification
©2010 Siemens Protection Devices Limited
Chapter 3 Page 21 of 49
2.5
49 Thermal Overload
2.5.1 Reference
Parameter
Value
Is
Overload setting
0.10, 0.11… 3
xIn
τ
Time constant setting
1, 1.5… 1000 min
2.5.2 Operate and Reset Level
Attribute
Value
I
ol
Overload level
100 %
Is
,
±
5 % or
±
1%
In
Reset level
≥
95 %
I
ol
Repeatability
±
1 %
-10 °C to +55 °C
≤
5 %
Variation
f
nom
- 3 Hz to
f
nom
+ 2 Hz
≤
5 %
2.5.3 Operate and Reset Time
Attribute
Value
t
op
Overload trip operate time
(
)
⎭
⎬
⎫
⎩
⎨
⎧
×
−
−
×
τ
=
2
2
2
P
2
I
I
I
ln
B
I
k
t
where
I
P
= prior current
,
±
5 % absolute or
±
100ms,
Repeatability
±
100ms
Figure 2-1 shows the thermal curves for various time constants.