The general tendency should be to set the tP1 time to at least 30 ms, if possible. Since it
is not possible to further increase the external load angle δ
Out
, it is necessary to reduce the
inner boundary of the oscillation detection characteristic. The minimum required value is
calculated according to the procedure listed in equation 413, 414, 415 and 416.
EQUATION1348 V1 EN (Equation 413)
min min
360 1 360 2.5 0.030 64.5 91.5
In si Out
f tP
d d
-
= °× × + = °× × + ° = °
EQUATION1349 V1 EN (Equation 414)
max1
min
155.75
75.8
91.5
2 tan
2 tan
2
2
d
-
= = = W
æ ö æ ö
×
×
ç ÷
ç ÷
è ø
è ø
S
in
Z
RLdInFw
EQUATION1350 V1 EN (Equation 415)
max1
75.8
0.61
123.5
= = =
RLdInFw
kLdRFw
RLdOutFw
EQUATION1351 V1 EN (Equation 416)
Also check if this minimum setting satisfies the required speed for detection of
consecutive oscillations. This requirement will be satisfied if the proposed setting of tP2
time remains higher than 10 ms, see equation
417.
max
91.5 64.5
2 10.7
360 7 360
In Out
sc
tP ms
f
d d
-
° - °
= = =
× ° × °
EQUATION1352 V1 EN
(Equation 417)
The final proposed settings are as follows:
RLdOutFw = 123.5Ω
kLdRFw = 0.61
tP1 = 30 ms
tP2 = 10 ms
Consider RLdInFw = 75.0Ω.
Section 8 1MRK 506 369-UUS -
Impedance protection
442 Line distance protection REL670 2.2 ANSI
Application manual
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