Functions
6-266
7SA6 Manual
C53000-G1176-C156-2
Figure 6-138Logic diagram of the thermal overload protection
6.19.2 Applying the Function Parameter Settings
General Informa-
tion
A precondition for the use of the thermal overload protection is that
Overload
=
Enabled
was configured under address
142
(Section 5.1). It can be switched
On
or
Off
under address
4201
Ther. OVERLOAD
. Furthermore
Alarm Only
can be set.
With that latter setting the protection function is active but only outputs an alarm when
the tripping temperature is reached, i.e. the output function “
Th.O/L TRIP
” is not ac-
tive.
k–factor
The rated current of the device is taken as the base current for detecting an overload.
The setting factor k is set under address
4202
K-FACTOR
. It is determined by the re-
lation between the permissible thermal continuous current and this rated current:
The permissible continuous current is at the same time the current at which the e-func-
tion of the overtemperature has its asymptote. It is not necessary to determine the trip-
ping temperature since it results automatically from the final rise temperature at k ·
I
N
.
Manufacturers of electrical machines usually state the permissible continuous current.
If no data are available, k is set to 1.1 times the rated current of the protected object.
For cables, the permissible continuous current depends on the cross section, the in-
sulation material, the design and the way they are laid, and can be derived from the
relevant tables.
Please note that the overload capability of electrical equipment relates to its primary
current. This has to be considered if the primary current differs from the rated current
of the current transformers.
L3
L2
L1
I
L3
I
L2
I
L1
>BLK ThOverload
&
4203
TIME CONSTANT
Θ
4202
K–FACTOR
I>
4205
I ALARM
4206
CALC. METHOD
Θ
>
4204
Θ
ALARM
Θ
max
Θ
Θ
(
I
max
)
Θ≥
1
&
&
≥
1
4201
Ther. OVER LOAD
Alarm Only
OFF
ON
“1“
FNo 1503
FNo 1521
FNo 1515
FNo 1516
Th.O/L
Θ
Alarm
Th.O/L I Alarm
Th.O/L TRIP
i
2
FNo 1517
Th.O/L Pickup
&
≥
1
k
I
m ax
I
N
------------
=
Summary of Contents for siprotec 7SA6
Page 2: ...Siemens Aktiengesellschaft Book No C53000 G1176 C156 2 ...
Page 18: ...xviii 7SA6 Manual C53000 G1176 C156 2 ...
Page 32: ...Introduction 1 14 7SA6 Manual C53000 G1176 C156 2 ...
Page 82: ...Hardware and Connections 2 50 7SA6 Manual C53000 G1176 C156 2 ...
Page 119: ...SIPROTEC 4 Devices 4 25 7SA6 Manual C53000 G1176 C156 2 Figure 4 20 CFC Logic example ...
Page 190: ...Configuration 5 62 7SA6 Manual C53000 G1176 C156 2 ...
Page 652: ...Installation and Commissioning 8 78 7SA6 Manual C53000 G1176 C156 2 ...
Page 724: ...Technical Data 10 56 7SA6 Manual C53000 G1176 C156 ...
Page 800: ...Appendix A 76 7SA6 Manual C53000 G1176 C156 2 ...
Page 866: ...Appendix B 66 7SA6 Manual C53000 G1176 C156 2 ...