VAMP 210
Generator protection relay
Technical description
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VM210.EN004
The tripping area of the underexcitation stage in the PQ-plane
is set with the parameters Q1 and Q2, see Figure 2.2.10-1 and
Figure 2.2.10-2. When the tip of the power vector lies on the left
side of the P-axis and also to the left of the straight line
through Q1 and Q2, the stage starts. After the set operating
time the stage operates, if the fault situation still persists.
100% = Sgen
80%
P
Q
Q2
Q1
P-Q-Circle1
Figure 2.2.10-1 Setting of the underexcitation stage by means of the par-
meters Q1 and Q2.The shaded area constitutes the area of operation. In the
above example the operation depends on both P and Q, because the
operating line has an 8°slope (Q1 - Q2 = 11%).
100% = Sgen
80%
P
Q
Q2
Q1
P-Q-circle2
Figure 2.2.10-2 Setting of the underexcitation stage by means of the par-
meters Q1 and Q2.The shaded area constitutes the area of operation. In the
above example the operation solely depends on the reactive power, because
the operating line is vertical (Q1 - Q2 = 0%).