Toshiba GR200 Series Instruction Manual page 59

Line differential protection ied

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function keeps calculating the charging current in response to the running line-voltage

provided by the VT on the line. As a result, the DIFL function can compensate for the charging

To apply the compensation into the DIFL function, the user should set line charging

current for setting [DIFL-IcC] and rated-line voltage for setting [DIFL-Vn]. The line capacitance

is computed between the relays at local and remote-terminals using the settings. That is, the

line capacitance is divided by two when the number of the IEDs is two. On the other hand, the

line capacitance is divided by three when the number of the relays is three†.

†Note: If one of the three relays is not operated during testing, the line capacitance is

divided by two.

For the provision of the line voltage, the relays can keep calculating the sharing charging

current per sample-by-sample basis. The equation is denoted as follows:

Ic = line charging current

C = line capacitance calculated using the settings [DIFL-IcC] and [DIFL-Vn]

V = line voltage measured

By using the Ic, the DIFL function can calculate a line current compensated per a sample-

by-sample basis as follows:

I = compensated current

I' = actual measured current

All necessary phase information has to be taken account basically. This is because the

DIFL function calculates both the charging current and the compensated line current per

sample-by-sample basis.

6F2S1914 (0.49)

GRL200 (Soft 033 & 037)

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