Toshiba GR200 Series Instruction Manual page 81

Calculation in Z*G-CovCoeff
The user can get the recommended setting value of [Z1G-CovCoeff] by the following equations.
First, the recommended setting value can be expressed by Equation (2.1-36).
Setting [Z1G-CovCoeff] = Margin ×
In this equation, the compensated 'setting[Z1G-X.Reach]' is can be expressed by Equation
(2.1-37).
Compensated 'setting [Z1G-X.Reach]' = (1 +
Finally, Equation (2.1-38) is derived from Equations (2.1-36) and (2.1-37).
Setting [Z1G-CovCoeff] = Margin × ( 1 +
However, depending on the value of "kxs", the calculation result of [Z1G-CovCoeff] value may
be small, so it is recommended that the definition value of [Z1G-CovCoeff] be as follows.
(a) If the calculation result is more than 1.5
Defined value is calculation result.
(b) If the calculation result is 1.5 or less
Defined value is 1.5.
Testing
Note that testing of a single phase to ground fault by standard methods will result in failures
at the resistance line boundary, because the resistance line of the 'Covering zones' is set to
the same value as the operating zone. This is due to test equipment applying the zero-
sequence compensation on a 'system' basis, rather than on a 'per zone' basis.
Command protection feature
2.1.6
The means of telecommunication makes possible for protective relays to exchange its operation
information. If the protective relays locate at each end of the protected line with the
telecommunication, the distance protection functions can determine whether the fault is
internal or external to the protected line.
As for the ZS, we provide the user the function of distance protection telecommunicated
as command protection (ZCSF and ZCSR). As for the ZG, we also provide the user the ZCSF
and ZCSR for the command protection. The user should take case that, discussed here are the
elements and characteristic of the command protection only; we provide the operation
Compensated 'setting [Z1G-X.Reach]'
Setting [ Z1G-X.Reach ]
������
−1
100
) × Setting [Z1G-X.Reach]
3
������−100
) × Setting [Z1G-X.Reach]
= (1 +
300
������ − 100
)
300
Margin = 1.2
- 60 -
6F2S1915 (0.46)
(2.1-36)
(2.1-37)
(2.1-38)
GRZ200 (Soft 031 & 032)