7SR210 & 7SR220 Description of Operation
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3.14 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 A binary or virtual input, function key or remote data Comms.
Figure 3.14-1 Logic Diagram: NPS Overvoltage Protection (47)
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