Siemens 7SR224 - Voltage Protection: Negative Phase Sequence Overvoltage (47); Figure 3.11-1 Logic Diagram: NPS Overvoltage Protection (47)

(1) Description of Operation 7SR224
©2009 Siemens Protection Devices Limited Page 37 of 66
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)