Specifications

7SR242 Duobias Performance Specification
©2010 Siemens Protection Devices Limited Chapter 3 - Page 21 of 45
2.5 49 Thermal Overload
2.5.1 Reference
Parameter Value
Is
Overload setting 0.10, 0.11… 3 xIn
W
Time constant setting 1, 1.5… 1000 min
2.5.2 Operate and Reset Level
Attribute Value
I
ol
Overload level
100 % Is, r 5 % or r 1% In
Reset level
t 95 % I
ol
Repeatability
r 1 %
-10 °C to +55 °C
d 5 %
Variation
f
nom
- 3 Hz to f
nom
+ 2 Hz
d 5 %
2.5.3 Operate and Reset Time
Attribute Value
t
op
Overload trip operate time

¿
¾
½
¯
®

u

uW
2
2
2
P
2
I
II
ln
B
Ik
t
where I
P
= prior current
, r 5 % absolute or r 100ms,
Repeatability
r 100ms
Figure 2-1 shows the thermal curves for various time constants.