Siemens 7SJ85 - Voltage Differential Protection for Capacitors; Overview of Functions; Structure of the Function; General Functionality

Voltage Differential Protection for Capacitors
Overview of Functions
The Voltage differential protection function (ANSI 87V) can be applied if the capacitor offers a voltage tap to
measure the 3-phase voltage within the capacitor installation. The function:
•
Calculates the differential voltage between busbar and tap voltage by applying a matching factor
•
Works as a capacitor unbalance function for protection of faults in capacitor elements (C elements)
Structure of the Function
The Voltage differential protection function is used in the Capacitor bank function group. The function is
preconfigured at the factory with one protection stage Vdiff>.
A maximum of 4 protection stages Vdiff> can be operated simultaneously in the function.
The General functionality (including compensation) works across all stages.
[dw_strucVoldi-060213-01.vsd, 1, en_US]
Figure 7-36 Structure of the Voltage Differential Protection Function
General Functionality
Description
The General functionality is structured in the following parts:
•
Calculation of the differential voltage V
diff.
•
Compensation of an operational differential voltage V
diff.
7.7
7.7.1
7.7.2
7.7.3
7.7.3.1
Capacitor Bank Protection
7.7 Voltage Differential Protection for Capacitors
1032 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017