ABB RELION 650 Series Applications Manual page 167

1MRK 505 363-UEN A
All the directional protection modes have a residual voltage release level setting
is set in % of
residual voltage to be detected.
tDef is the definite time delay, given in s, for the directional residual current protection.
tReset is the time delay before the definite timer gets reset, given in s. With a tReset time of
few cycles, there is an increased possibility to clear intermittent earth faults correctly. The
setting shall be much shorter than the set trip delay. In case of intermittent earth faults, the
fault current is intermittently dropping below the set value during consecutive cycles.
Therefore the definite timer should continue for a certain time equal to
fault current has dropped below the set value.
The characteristic angle of the directional functions
normally set equal to 0° in a high impedance earthed network with a neutral point resistor as
the active current component is appearing out on the faulted feeder only.
to -90° in an isolated network as all currents are mainly capacitive.
ROADir is Relay Operating Angle. ROADir is identifying a window around the reference
direction in order to detect directionality.
than ROADir from RCADir the function is blocked. The setting can be used to prevent
unwanted operation for non-faulted feeders, with large capacitive earth fault current
contributions, due to CT phase angle error.
INCosPhi> is the operate current level for the directional function when OpMode is set
3I0Cosfi . The setting is given in % of IBase . The setting should be based on calculation of the
active or capacitive earth fault current at required sensitivity of the protection.
SN> is the operate power level for the directional function when OpMode is set 3I03U0Cosfi .
The setting is given in % of
capacitive earth fault residual power at required sensitivity of the protection.
The input transformer for the Sensitive directional residual over current and power protection
function has the same short circuit capacity as the phase current transformers. Hence, there is
no specific requirement for the external CT core, i.e. any CT core can be used.
If the time delay for residual power is chosen the delay time is dependent on two setting
parameters.
multiplier. The time delay will follow the following expression:
=
t
inv
3I 3U cos (measured)
EQUATION1957 V1 EN-US
INDir> is the operate current level for the directional function when OpMode is set 3I0 and fi .
The setting is given in % of
current at required sensitivity of the protection.
OpINNonDir> is set On to activate the non-directional residual current protection.
INNonDir> is the operate current level for the non-directional function. The setting is given in
IBase . This function can be used for detection and clearance of cross-country faults in a
% of
shorter time than for the directional function. The current setting should be larger than the
maximum single-phase residual current on the protected line.
TimeChar is the selection of time delay characteristic for the non-directional residual current
protection. Definite time delay and different types of inverse time characteristics are available:
Application manual
UBase . This setting should be chosen smaller than or equal to the lowest fault
SBase . The setting should be based on calculation of the active or
SRef is the reference residual power, given in % of SBase . kSN is the time
×
kSN Sref
j
× ×
0 0
IBase . The setting should be based on calculation of the earth fault
RCADir is set in degrees. RCADir is
ROADir is set in degrees. For angles differing more
Section 8
Current protection
UNRel> which
tReset even though the
RCADir is set equal
(Equation 115)
161