ABB RELION 620 Series Technical Manual page 563

1MAC504801-IB E
5.6
5.6.1
5.6.2
5.6.3
5.6.4
620 series ANSI
Technical Manual
RTD based thermal protection 38
Identification
Function description
RTD based thermal protection
Function block
GUID-89CECF30-A255-4DCA-B5FD-3F3FCB183ACD V3 EN
Figure 274: Function block
Functionality
The RTD based thermal protection function 38 is used as a general protection with many
possible application areas as it has flexible measuring and setting facilities. The function
can be used as an under- or overprotection with a settable absolute hysteresis limit. The
function operates with the definite time (DT) characteristics.
The function contains a blocking functionality. It is possible to block function outputs, the
definite timer or the function itself, if desired.
If the quality of the input signal is not good, the function is blocked. Also, in case several
RTD inputs are connected through the MAX3 function block into the 38 input - quality of
all RTD inputs must be good.
Operation principle
The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are "Enable" and "Disable".
The operation of 38 can be described using a module diagram. All the modules in the
diagram are explained in the next sections.
Protection-related functions
IEC 61850 IEC 60617
identification identification
MAPGAPC ThA> ThB>
Section 5
ANSI/IEEE C37.2
device number
38
557