Toshiba GR200 Series Instruction Manual page 105

Line differential protection ied

Hide thumbs Also See for GR200 Series:

Table of Contents

Nature of outflowing current in case of internal fault

The user should consider outflows when the DIFL function is applied for the following lines:

Account of DIFL settings for a single line with outer loop

Figure 2.7-10 shows a three-terminal line (lines GJ, JH, and JK) with an outer loop (loop-

circuit HK). Suppose a fault occurs on the line JH. The fault current (I F ) flowing at the

terminal-G is divided into I F1 and I F2 at the junction-J, then the I F2 re-enters into the line

JH. This is because the terminal-H is connected by the loop-circuit HK.

Figure 2.7-10 Single line with three-terminals with outer loop circuit

Account of DIFL settings for parallel lines

Figure 2.7-11 shows a double-circuit line with three terminals; the outer loop is generated

when the CB on the line-GJ is open. The fault current I F flowing out at the terminal G divided

into I F1 and I F2 at the junction-J'; then the I F2 re-enter into the line J'H' through the parallel

line JH. The larger current outflows from the terminal-K when a fault is in close proximate

the terminal-G and the power source behind the terminal-K is weaker. In general, a half of the

fault current leaving from the terminal-G may re-enter in the line-J'H', provided the terminal-

K is very close to the junction-J and the terminal-K does not have a power source itself.

Figure 2.7-11 Double lines with three-terminals

6F2S1914 (0.49)

GRL200 (Soft 033 & 037)

Chapters

Table of Contents