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

3.11 V P
OLTAGE
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
47-n Element
Enabled
Disabled
&
Inhibit 47-n
VL1
NPS
VL2
Filter
VL3
©2009 Siemens Protection Devices Limited
: N
ROTECTION EGATIVE
A binary or virtual input.
47-n Setting
47-n Hysteresis
c
>
V2

Figure 3.11-1 Logic Diagram: NPS Overvoltage Protection (47)

P S O
HASE EQUENCE
47-n Delay
(1) Description of Operation 7SR224
(47)
VERVOLTAGE
General Pickup
47-n
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