Siemens 6MD85, Manual

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Parameter:
Behav. at I> Imax therm.
•
Default setting
(_:114) Behav. at I> Imax therm.
=
current limiting
The
Behav. at I> Imax therm.
parameter is used to select the process by which the function reacts to
short-circuit currents. To prevent premature tripping of the overload protection at low time constants, high
preloading and high short-circuit currents, the thermal replica can be modified.
Parameter Value Description
freeze therm. rep.
If input currents exceed the
Imax thermal
parameter, the thermal
replica will be frozen for the time the parameter is exceeded. This param-
eter value is provided to enable compatibility with older products!
current limiting
The input currents are limited to the value set in the
Imax thermal
parameter. If the measured current exceeds the set current value, the
limited current value is supplied to the thermal replica. An advisable current
threshold is approx. 2 to 2.5 I
rated, obj
.
Parameter:
Temperature sensor
•
Default setting
(_:44) Temperature sensor
=
none
With the
Temperature sensor
parameter, you determine which temperature sensor to use to detect the
ambient temperature.
A temperature sensor (RTD = Resistance Temperature Detector) is used to measure the ambient temperature
of the protected object and feed it to the device via an RTD unit. The Thermal overload protection, 3-phase -
advanced function receives the measured temperature value via the functions RTD unit Ether. or RTD unit
Serial from the function group Analog transformer.
Parameter:
Default temperature
•
Default setting
(_:118) Default temperature
=
40°C
The
Default temperature
is set as ambient temperature under the following conditions:
•
No temperature sensor for measuring the ambient temperature is connected.
•
The temperature measurement is faulty and the last measured temperature value is less than the
Default temperature
.
Siemens recommends using the default setting.
Parameter:
Minimal temperature
•
Default setting
(_:117) Minimal temperature
=
-20°C
If the measured ambient temperature drops below the set value, the set value is assumed as the ambient
temperature. If the overload protection works with a prespecified outside temperature, and this temperature
drops below the value set in the
Minimal temperature
parameter, the
Minimal temperature
is also
used.
Settings
Addr. Parameter C Setting Options Default Setting
49 Th.overl. #
_:1 49 Th.overl. #:Mode
•
off
•
on
•
test
off
_:2 49 Th.overl. #:Operate &
flt.rec. blocked
•
no
•
yes
no
7.26.6
Protection and Automation Functions
7.26 Thermal Overload Protection, 3-Phase - Advanced
SIPROTEC 5, High-Voltage Bay Controller, Manual 889
C53000-G5040-C015-9, Edition 11.2017