Siemens 7SJ85 - Thermal Overload Protection for Capacitor Banks; Overview of Functions; Structure of the Function; Function Description

Thermal Overload Protection for Capacitor Banks
Overview of Functions
The function Thermal overload protection for capacitor banks (Overload RLC) protects RLC filter circuit
elements in a capacitor bank from thermal overload.
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i
NOTE
The structure of the function Overload RLC differs only slightly from that of the standard Thermal over-
load protection, 3-phase – advanced function. In this chapter, only the differences between these and
the standard function are described.
For more information, refer to the function description Thermal overload protection, 3-phase –
advanced starting from chapter 6.19.1 Overview of Functions.
Structure of the Function
The function Overload RLC is used in the Capacitor bank function group.
The General functionality differs from the standard Thermal overload protection, 3-phase – advanced
function and consists of:
•
Measuring-point selection
•
Selecting whether the rated current of the capacitor bank or of the protected object (for example, reactor
or resistor) is taken as reference value
•
Setting the rated current of the protected object (for example, reactor or resistor) within the function if
necessary
[dwtolp_rlc-200813, 3, en_US]
Figure 7-4 Structure/Embedding of the Function
Function Description
A feature of the function Overload RLC is the Measuring-point selection. A capacitor bank can include
multiple filter circuits. Each filter circuit can include, for example, a 3-phase current transformer, each of
which is assigned a measuring point. In order to protect all filter circuits, multiple instances of the function
Overload RLC can be created. Each instance of the function is assigned to a measuring point via the Meas-
uring-point selection.
The function is structured such that the Measuring-point selection is superordinate to the Thermal overload
protection stage.
Measuring-Point Selection
With the parameter MP selection, you can select from a list of measuring points a measuring point that is
connected to the I 3ph RLC interface in the Capacitor bank function group. The function Overload RLC
processes the current that is connected to the measuring point.
For more information, refer to the description of the Capacitor bank function group starting from Chapter
5.4.1 Overview.
7.3
7.3.1
7.3.2
7.3.3
Capacitor Bank Protection
7.3 Thermal Overload Protection for Capacitor Banks
SIPROTEC 5, Overcurrent Protection, Manual 973
C53000-G5040-C017-8, Edition 07.2017