Thermal Overload; Reference; Operate And Reset Level; Operate And Reset Time - Siemens 7SR224 Technical Manual

2.5

49 Thermal Overload

2.5.1

Reference

Parameter
Is Overload setting
τ
Time constant setting
2.5.2

Operate and Reset Level

Attribute
I Overload level
ol
Reset level
Repeatability
-10 °C to +55 °C
Variation
f
nom
2.5.3

Operate and Reset Time

Attribute
t Overload trip operate time
op
Repeatability
Figure 2-1 shows the thermal curves for various time constants.
©2010 Siemens Protection Devices Limited
Value
0.10, 0.11... 3 xIn
1, 1.5... 1000 min
Value
100 % Is, ± 5 % or ± 1% In
≥ 95 % I
± 1 %
≤ 5 %
+ 2 Hz ≤ 5 %
- 3 Hz to f
nom
Value
= τ ×
t
where I
± 100ms
7SR224 Argus Performance Specification
ol
⎧ ⎫
−
2 2
I I
⎨ ⎬
P
ln
( )
− ×
, ± 5 % absolute or ± 100ms,
2
2
⎩ ⎭
I k I
B
= prior current
P
Chapter 3 Page 21 of 49