Toshiba GR200 Series Instruction Manual page 136

In ZG, this function provides the compensation factors for all elements and these factors
are defined with settings. For example, for Z1G, the settings [Z1G-Krs], [Z1G-Kxs], [Z1G-Krm],
[Z1G-Kxm] are provided. Where, "s" refers to the protected line; the resistance "r"; the
reactance "x" reflect its property and "m" refers to a mutual circuit line for parallel line
applications.
Table 2.10-3 ZG compensation factors in lines
Element Settings for Protected line
Z1G
Z1XG [Z1XG-Krs], [Z1XG-Kxs]
Z2G
Z3G
Z4G
Z5G
Measuring the positive-sequence impedance to the fault point is necessary. Therefore, for
a single circuit line, the current input to the earth fault-measuring element is compensated by
the residual current (3I 0 ) of the protected line.
On the other hand, for a double circuit line, the current input is compensated by the
residual current (3I 0 ) of the protected line and residual current (3I 0 ') of the adjacent line.
Generally, the following equation is used to compensate the zero-sequence voltage drop,
in this example for the case of phase "a".
where,
Va: Phase "a" voltage
Ia: Phase "a" current
I : Zero-sequence current of the protected line
0
I : Zero-sequence current of the adjacent line
0m
Z : Positive-sequence impedance (Z
1
Z : Zero-sequence impedance (Z
0
Z : Zero-sequence mutual impedance (Z
om
Equation (2.10-32) can be presented as follows:
[Z1G-Krs], [Z1G-Kxs]
[Z2G-Krs], [Z2G-Kxs]
[Z3G-Krs], [Z3G-Kxs]
[Z4G-Krs], [Z4G-Kxs]
[Z5G-Krs], [Z5G-Kxs]
Va = (Ia − �� ) × Z1 + ��
0
- 113 -
Settings for Parallel line
[Z1G-Krm], [Z1G-Kxm]
[Z1XG-Krm], [Z1XG-Kxm]
[Z2G-Krm], [Z2G-Kxm]
[Z3G-Krm], [Z3G-Kxm]
[Z4G-Krm], [Z4G-Kxm]
[Z5G-Krm], [Z5G-Kxm]
× �� + �� × ��
0 0 0�� 0��
= R + jX )
1 1 1
= R + jX )
0 0 0
= R + jX
om om
6F2S1914 (0.49)
(2.10-32)
)
om
GRL200 (Soft 033 & 037)