Toshiba GR200 Series - (iii) Element equations for reactance characteristic

6F2S1914 (0.49)
GRL200 (Soft 033 & 037)
- 98 -
I = fault current
Zs = reach setting
Vso = offset reach setting
X
R
IZs
V
S1=V–IZs
S2=Vp
V
–IZso
S2=V+IZso
o
Offset Mho element
Figure 2.10-6 Offset Mho characteristic on impedance plane
Figure 2.10-6 illustrates a voltage diagram in the offset Mho characteristic; the angle
comparison between the S1 and S2 phases are performed using Equations (2.10-19) and
(2.10-20). The offset Mho characteristic is obtained by dividing the voltage of Figure 2.10-6 by
current I.
(iii) Element equations for reactance characteristic
It is possible that the Mho characteristic operate with reactance characteristic; a level line or
a gradual descent line toward the R-axis is provided for the reactance characteristic. The
gradual descent one is set using variables Xs, θ1, and θ2, as shown in Figure 2.10-7.
X
R
a. Reactance element with a level line
θ1
θ2
Xs
knee
X
R
Xs
b. Reactance element with a gradual descent line
o
o
Mho element
Reactance element
Figure 2.10-7 Reactance characteristics
The composite characteristic is available only when the load current flows from the local-
end to the remote-end. If the load current flows oppositely from the remote-end to the local-