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7SR11 & 7SR12 Description Of Operation
©2017 Siemens Protection Devices Limited Chapter 1 Page 57 of 88
3.15 Voltage Protection: Under/Over Frequency (81) – 7SR12
Four under/over frequency elements are provided in the 7SR12 relay –
81-1, 81-2, 81-3 & 81-4.
The relay utilises fundamental voltage measurement values for this function. The frequency calculation is based
on the highest input voltage derived from the voltage selection algorithm.
The relay utilises fundamental frequency RMS voltage for this function. All under/over frequency elements have a
common setting to measure phase to phase
(Ph-Ph)
or phase to neutral
(Ph-N)
voltage using the
Frequency
Input mode
setting
.
Frequency elements are blocked if all phase voltages fall below the
81 U/V Guard
setting.
The sense of the element (under-frequency or over-frequency) is set by the
81-n Operation
setting.
81-n Setting
sets the pick-up voltage level for the element.
An output is given after elapse of the
81-n Delay
setting.
The
81-n Hysteresis
setting allows the user to vary the pick-up/drop-off ratio for the element.
Operation of the under/over frequency elements can be inhibited from:
Inhibit 81-n
A binary or virtual input, or function key.
81-n U/V Guarded
Under voltage guard element.
or
> <
General Pickup
81-n
Inhibit 81-n
81-n Hysteresis
81-n Delay
c
&
81-n Setting
81-n Operation
81-n Element
Enabled
Disabled
81-n U/V Guarded
Yes
&
Voltage
Selection
VL1
VL2
VL3
F
<
&
81 U/V Guard
Setting
<
<
Figure 3-30 Logic Diagram: Under/Over Frequency Detector (81)
Summary of Contents for Argus 7SR11
Page 1: ...Energy Management 7SR11 7SR12 Argus Overcurrent Relay Reyrolle Protection Devices ...
Page 2: ......
Page 4: ...7SR11 7SR12 Argus Contents 2015 Siemens Protection Devices Limited Page 2 of 2 ...
Page 170: ...7SR120 Technical Manual Chapter 4 Page 2 of 84 2017 Siemens Protection Devices Limited ...
Page 174: ...7SR120 Technical Manual Chapter 4 Page 6 of 84 2017 Siemens Protection Devices Limited ...
Page 196: ...7SR120 Technical Manual Chapter 4 Page 28 of 84 2017 Siemens Protection Devices Limited ...
Page 242: ...7SR120 Technical Manual Chapter 4 Page 74 of 84 2017 Siemens Protection Devices Limited ...
Page 244: ...7SR120 Technical Manual Chapter 4 Page 76 of 84 2017 Siemens Protection Devices Limited ...
Page 246: ...7SR120 Technical Manual Chapter 4 Page 78 of 84 2017 Siemens Protection Devices Limited ...
Page 254: ...7SR11 7SR12 Installation Guide Chapter 5 Page 2 of 32 2017 Siemens Protection Devices Limited ...
Page 358: ...7SR11 7SR12 Applications Guide Page 2 of 48 2017 Siemens Protection Devices Limited ...
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