Do not forget to adjust the setting of load encroachment resistance
RLdFwd in Phase selection with load encroachment (FDPSPDIS, 21 or
FRPSPDIS, 21) 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
FDPSPDIS (21) or FRPSPDIS (21) to follow the condition presented in
equation
418.
Index PHS designates correspondence to FDPSPDIS (21) or FRPSPDIS
(21) function and index PSD the correspondence to ZMRPSB (68)
function.
tan( )
arctan
PSD
PHS
LdAngle
LdAngle
KLdRFw
³
é ù
ê ú
ë û
EQUATION1737-ANSI V1 EN (Equation 418)
Consider equation 419,
EQUATION1739-ANSI V1 EN (Equation 419)
then it is necessary to set the load angle in FDPSPDIS (21) or FRPSPDIS (21) function to
not less than equation
420.
PSD
PHS
tan(LdAngle )
tan(25 )
LdAngle arctan arctan 37.5
kLdRFw 0.61
°
³ = = °
é ù
é ù
ê ú
ê ú
ë û
ë û
EQUATION1738-ANSI V1 EN
(Equation 420)
It is recommended to set the corresponding resistive reach parameters in reverse direction
(RLdOutRv and kLdRRv) to the same values as in forward direction, unless the system
operating conditions, which dictate motoring and generating types of oscillations,
requires different values. This decision must be made on basis of possible system
contingency studies especially in cases, when the direction of transmitted power may
change fast in short periods of time. It is recommended to use different setting groups for
operating conditions, which are changing only between different periods of year (summer,
winter).
System studies should determine the settings for the hold timer tH. The purpose of this
timer is, to secure continuous output signal from Power swing detection function
(ZMRPSB, 68) during the power swing, even after the transient impedance leaves
ZMRPSB (68) operating characteristic and is expected to return within a certain time due
1MRK 506 369-UUS - Section 8
Impedance protection
Line distance protection REL670 2.2 ANSI 443
Application manual
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