Siemens 7SR51 Device Manual page 345

[dw_7SR5_function81SettingExample, 1, en_US]
•
First stage
Least important load such as domestic customers.
•
Second stage
Separate stage load such as further domestic load and infrastructure supply.
•
Third stage
Light industrial customer load.
•
Fourth stage
Higher importance light industrial load.
•
Unaffected loads
Critical load which should be maintained whenever possible.
Settings for timings should be assessed depending on network requirements and customer practices.
Frequency setting should avoid expected network variations. Timing should allow for system fault detection
and clearance. Timing between stages should allow for CB operation and system recovery following shedding
of previous stage.
Element
81-1
81-1
81-1
81-1
81-1
81-1
81-2
81-2
81-2
81-2
81-2
81-2
81-3
81-3
81-3
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019
81-1 Element
81-1 Operation
81-1 Setting
81-1 Hysteresis
81-1 Delay
81-1 Input Selection
81-2 Element
81-2 Operation
81-2 Setting
81-2 Hysteresis
81-2 Delay
81-2 Input Selection
81-3 Element
81-3 Operation
81-3 Setting
Protection and Automation Functions
5.27 81 Frequency Protection – "f>" or "f<"
Setting Values
Enabled
Under
49.5 Hz
0.1 %
3 s
VT1/2/3
Enabled
Under
49.5 Hz
0.1 %
5 s
VT1/2/3
Enabled
Under
49.2 Hz
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