7SR224 Argus Description of Operation
3.11 Voltage Protection: Negative Phase Sequence
Overvoltage (47)
Negative phase sequence (NPS) voltage (V2) is a measure of the quantity of unbalanced voltage in the system.
The relay derives the NPS voltage from the three input voltages (VL1, VL2 and VL3).
Two elements are provided.
47-n Setting sets the pick-up voltage level for the element.
The 47-n Hysteresis setting allows the user to vary the pick-up/drop-off ratio for the element.
An output is given after elapse of the 47-n Delay setting.
Operation of the negative phase sequence voltage elements can be inhibited from:
Inhibit 47-n A binary or virtual input.
Inhibit 47-n
47-n Element
Enabled
Disabled
47-n
47-n Delay
&
c
47-n Hysteresis
>
47-n Setting
VL1
VL2
VL3
NPS
Filter
V2
General Pickup
Figure 3.11-1 Logic Diagram: NPS Overvoltage Protection (47)
©2010 Siemens Protection Devices Limited Chapter 1 Page 36 of 70
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