Siemens 7SJ85 - Voltage-Dependent Overcurrent Protection, Phases; Overview of Functions; Structure of the Function

Voltage-Dependent Overcurrent Protection, Phases
Overview of Functions
The Voltage-dependent overcurrent protection (ANSI 51V) function:
•
Detects short circuits affecting electric equipment
•
Can be used for special network conditions where the overcurrent pickup level should be decreased
depending on the fault voltage
•
Can be used for generators where the excitation voltage is derived from the machine terminals and the
overcurrent pickup should be kept depending on the fault voltages
Structure of the Function
The Voltage-dependent overcurrent protection function is used in protection function groups with 3-phase
current and voltage measurement.
The function Voltage-dependent overcurrent protection comes with the following factory-set stages:
•
Inverse-time overcurrent protection, voltage-dependent stage
•
Definite-time overcurrent protection, undervoltage seal-in stage
In this function, the following stages can operate simultaneously:
•
A maximum of 2 inverse-time overcurrent protection, voltage-dependent stages
•
A maximum of 2 inverse-time overcurrent protection, voltage-released stages
•
A maximum of 2 definite-time overcurrent protection, undervoltage seal-in stages
•
A maximum of 2 definite-time overcurrent protection, voltage-released undervoltage seal-in stages
[dw_stuvol_release, 3, en_US]
Figure 6-25 Structure/Embedding of the Function
6.4
6.4.1
6.4.2
Protection and Automation Functions
6.4 Voltage-Dependent Overcurrent Protection, Phases
360 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017