Toshiba GR-200 Series Instruction Manual page 90

(I ) for stage 1 with the setting [SEF1] when the scheme switch [SEF1-Dir]=Forward. Setting
SEF
of the sensing angle (θ) is configured by the setting [SEF1-Angle] with the value of θ set in the
range of -90 – 90°. Figure 2.4-2 shows an example of an angle and a characteristic using the θ.
The operation of the SEF element is based upon the following equation.
where
Ie = Residual current
Ve = Residual voltage
Vpol = reference voltage (or polarizing voltage; Ve180°)
φ= lagging angle
θ = SEF1 setting angle ([SEF1-Angle])
I = Setting value of the SEF1 element ([SEF1])
SEF
SEF_Vpol = Setting value of the polarizing voltage ([SEF1-Vpol])
Note: In the case of an internal fault, the phase angle is equal to the angle of the zero-
sequence impedance of the system, in a directly earthed system this value is in
the range of approximately 50° to 90°. The sensing angle θ of the SEF element can
be set between -90° to 90°. The minimum voltage necessary to maintain
directionality should be applied from 0.5 to 100.0 V.
I ≥ I
e SEF
I × cos⁡(φ − |θ|) ≥ 0
e
≥ SEF_Vpol
V
e
- 71 -
6F2T0200 (0.15)
(2.4-1)
(2.4-2)
(2.4-3)
GRE200 (1,2)