ABB RELION RET670 - Page 462

76.5 64.5
1 13.3
360 2.5 360
In Out
si
tP ms
f
d d -
° - °
= = =
× ° × °
EQUATION1347 V1 EN-US (Equation 381)
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 382, 383, 384
and 385.
min
1 30tP ms=
EQUATION1348 V1 EN-US (Equation 382)
min min
360 1 360 2.5 0.030 64.5 91.5
In si Out
f tP
d d
-
= °× × + = °× × + ° = °
EQUATION1349 V1 EN-US (Equation 383)
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-US (Equation 384)
max1
75.8
0.61
123.5
= = =
RLdInFw
kLdRFw
RLdOutFw
EQUATION1351 V1 EN-US (Equation 385)
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 386.
max
91.5 64.5
2 10.7
360 7 360
In Out
sc
tP ms
f
d d -
° - °
= = =
× ° × °
EQUATION1352 V1 EN-US (Equation 386)
The final proposed settings are as follows:
RLdOutFw = 123.5Ω
kLdRFw = 0.61
tP1 = 30 ms
Section 8 1MRK 504 163-UUS A
Impedance protection
456 Transformer protection RET670 2.2 ANSI
Application manual