Voltage Protection: Negative Phase Sequence Overvoltage (47) - 7Sr22; Figure 3.12-1 Logic Diagram: Nps Overvoltage Protection (47) - Siemens 7SR21 Manual

3.12 Voltage Protection: Negative Phase Sequence
Overvoltage (47) – 7SR22
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 in the 7SR22 relay.
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
47-n Element
Enabled
Disabled
Inhibit 47-n
VL1
VL2
VL3

Figure 3.12-1 Logic Diagram: NPS Overvoltage Protection (47)

©2010 Siemens Protection Devices Limited
A binary or virtual input, or function key.
47-n Setting
&
47-n Hysteresis
c
>
V2
NPS
Filter
7SR21 & 7SR22 Argus Description of Operation
47-n Delay
Chapter 1 Page 45 of 71
General Pickup
47-n