Siemens 7SJ85 - Underfrequency Load Shedding; Overview of Functions; Structure of the Function

Underfrequency Load Shedding
Overview of Functions
The Underfrequency load shedding function:
•
Detects underfrequencies in the electrical power systems
•
Switches off the medium-voltage busbar or feeders that consume active power to stabilize the frequency
•
Maintains operations for the medium-voltage busbar or feeders that generate active power
Structure of the Function
The Underfrequency load shedding function can be used in the Voltage/Current 3-phase function group
and in the Line function group.
The Underfrequency load shedding function comes factory-set with 8 stages. A maximum of 12 stages can
be operated simultaneously within the function. These stages are identical in structure.
[dw_load shedding_Structure, 1, en_US]
Figure 6-213 Structure/Embedding of the Function
6.34
6.34.1
6.34.2
Protection and Automation Functions
6.34 Underfrequency Load Shedding
SIPROTEC 5, Overcurrent Protection, Manual 773
C53000-G5040-C017-8, Edition 07.2017