Toshiba GR200 Series Instruction Manual page 154

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 (2.10-36).
Setting [Z1G-CovCoeff] = Margin ×
In this equation, the compensated 'setting[Z1G-X.Reach]' is can be expressed by Equation
(2.10-37).
Compensated 'setting [Z1G-X.Reach]' = (1 +
Finally, Equation (2.10-38) is derived from Equations (2.10-36) and (2.10-37).
Setting [Z1G-CovCoeff] = Margin × ( 1 +
However, depending on the value of "kxs", the calculation result of [Z1G-CovCoeff] value may
be smaller, so it recommends the defined value for [Z1G-CovCoeff] 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.
Enhances in Z1S, Z1XS& Z5S zones
Similar to Z1G, Z1XG and Z5G zones, dedicated covering zones are provided for Z1S, Z1XS
and Z5S zones as they are used for internal fault phase detection logics. The settings [Z1S-
CovCoeff], [Z1XS-CovCoeff] and [Z5S-CovCoeff] are used for each reactance each setting
by multiplying this coefficient to each zone reach setting.
Since ZS elements do not need to consider zero-phase sequence compensation, and the
purpose of this coefficient setting is to detect a fault phase, 1.5 – 2.0 is recommended for the
settings.
Another common covering zone is used for Z2S, Z3S and Z4S elements, and as it is set
automatically inside the application calculation, the setting for this covering zone is not
required.
Compensated 'setting [Z1G-X.Reach]'
Setting [ Z1G-X.Reach ]
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−1
100
) × Setting [Z1G-X.Reach]
3
������−100
) × Setting [Z1G-X.Reach]
= (1 +
300
������ − 100
)
300
Margin = 1.2
- 131 -
6F2S1914 (0.49)
(2.10-36)
(2.10-37)
(2.10-38)
GRL200 (Soft 033 & 037)