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2.1
Thermal Overload (49)
Voltage Inputs:
Current Inputs:
Disable:
Map Pickup LED:
With reference to the Motor Thermal Overload Protection logic diagram (see chapter 1 'Description of Operation')
The current can be applied from a 3P balanced supply or phase by phase from a 1P supply. Alternatively the 3
phase current inputs can be connected in series and injected simultaneously from a single source.
The Thermal Overload Setting and Time Constant Setting can be considered together to calculate the operating
time for a particular applied current.
The following table lists operate times for a range of Time Constant Settings for an applied current of 2x the
Thermal Overload setting. Ensure that the thermal rating of the relay is not exceeded during this test.
Gn 49 TauH Heating Constant
The Thermal State must be in the fully reset condition in order to measure the operate time correctly. This can be
achieved by setting change in the Thermal protection settings menu or by pressing the Test/Reset button when
the Thermal Meter is shown in the Instruments Mode.
Reset the thermal State then apply 2x the Overload Setting current.
©2014 Siemens Protection Devices Limited
n/a
I
, I
, I
,
A
B
C
14, 37, 46, 48/66, 50BF, 50, 50N, 51, 51N, 60CTS
49 Trip self reset
1
2
3
4
5
10
15
20
25
30
50
100
Chapter 6) 7SR17 Commissioning and Maintenance Guide
Operate Time (sec)
17.3
34.5
51.8
69
86.3
173
259
345
432
51.8
863
1726
Page 15 of 62
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