Hitachi Relion 670 Series Applications Manual page 108

Section 7
Impedance protection
RLdInFw
EQUATION1350 V1 EN-US
kLdRFw
EQUATION1351 V1 EN-US
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 31.
tP 2
max
EQUATION1352 V1 EN-US
The final proposed settings are as follows:
RLdOutFw = 123.5Ω
kLdRFw = 0.61
tP1 = 30 ms
tP2 = 10 ms
Consider RLdInFw = 75.0Ω.
LdAngle
EQUATION1737-ANSI V1 EN-US
Consider equation 33,
LdAngle
PSD
EQUATION1739-ANSI V1 EN-US
102
Z
S
=
d
max1
æ ö
×
-
2 tan in min
ç ÷
è 2 ø
RLdInFw
= =
max1
RLdOutFw 123.5
d d
-
° -
91.5
= =
In Out
× ° ×
f 360 7 360
sc
Do not forget to adjust the setting of load encroachment resistance RLdFwd in Phase
selection with load encroachment (ZMFPDIS) to the value equal to or less than the calculated
value RLdInFw. It is at the same time necessary to adjust the load angle in ZMFPDIS to follow
the condition presented in equation 32.
Index PHS designates correspondence to ZMFPDIS function and index PSD the
correspondence to ZMBURPSB (68) function.
é
tan( LdAngle
³
arctan
ê
PHS
ë
KLdRFw
= °
j 25
=
max
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155.75
= =
75.8
æ ö
91.5
×
2 tan
ç ÷
è 2 ø
75.8
=
0.61
°
64.5
=
10.7 ms
°
ù
)
PSD
ú
û
1MRK511407-UUS Rev. N
W
Phasor measurement unit RES670
(Equation 29)
(Equation 30)
(Equation 31)
(Equation 32)
(Equation 33)
Application manual