REG 316*4 1MRB520049-Uen / Rev. F ABB Switzerland Ltd
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3.7.3. Three-phase voltage plausibility (Check-U3ph)
A. Application
Checking the plausibility of the three-phase voltage inputs for
· detection of residual voltage
· monitoring the asymmetry of the three-phase voltage system
due to the zero-sequence component
· supervision of the v.t. input channels.
B. Features
Evaluation of
· the sum of the three phase voltages
· the sequence of the three phase voltages
· provision for comparing the sum of the three phase voltages
with a residual voltage I/P
· adjustment of residual voltage amplitude
· blocking at high voltages (higher than 1.2 ´ U
N
)
· blocking of phase-sequence monitoring at low voltages
(below 0.4
´ U
N
phase-to-phase)
· insensitive to DC components
· insensitive to harmonics.
Evaluation of the phase voltages is only possible in the case of Y
connected input transformers, otherwise the residual component
cannot be detected.
C. Inputs and outputs
I. C.t./v.t. inputs:
· phase voltages
· neutral voltage (optional)
II. Binary inputs:
·
Blocking
III. Binary outputs:
· tripping
IV. Measurements:
· Difference between the vector sum of the three phase
voltages and the neutral voltage.
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