ABB Relion 650 Series Technical Manual page 103

1MRK 511 424-UEN B
Bay control REC650 2.2 IEC
Technical manual
Second harmonic feature
The overcurrent protection step can be restrained by a second harmonic component
in the measured current quantity (see table 39). However it shall be noted that this
feature is not applicable when one of the following measured currents is selected:
• PosSeq (positive sequence current)
• NegSeq (negative sequence current)
• UnbalancePh (unbalance phase current)
• UnbalancePh-Ph (unbalance phase-phase current)
This feature will prevent overcurrent step start if the second-to-first harmonic ratio
in the measured current exceeds the set level.
Directional feature
The overcurrent protection step operation can be made dependent on the relevant
phase angle between measured current phasor (see table 39) and measured voltage
phasor (see table 40). In protection terminology it means that the General currrent
and voltage protection (CVGAPC) function can be made directional by enabling
this built-in feature. In that case overcurrent protection step will only operate if the
current flow is in accordance with the set direction (Forward, which means
towards the protected object, or Reverse, which means from the protected object).
For this feature it is of the outmost importance to understand that the measured
voltage phasor (see table 40) and measured current phasor (see table 39) will be
used for directional decision. Therefore it is the sole responsibility of the end user
to select the appropriate current and voltage signals in order to get a proper
directional decision. CVGAPC function will NOT do this automatically. It will
simply use the current and voltage phasors selected by the end user to check for the
directional criteria.
Table 42 gives an overview of the typical choices (but not the only possible ones)
for these two quantities from traditional directional relays.
Table 42: Typical current and voltage choices for directional feature
Set value for the Set value for the
parameter parameter
CurrentInput VoltageInput
PosSeq PosSeq
NegSeq -NegSeq
3ZeroSeq -3ZeroSeq
Table continues on next page
Multipurpose protection
Comment
Directional positive sequence overcurrent function is
RCADir is from 45° to
obtained. Typical setting for
90° depending on the power system voltage level
(X/R ratio)
Directional negative sequence overcurrent function is
obtained. Typical setting for RCADir is from 45° to
90° depending on the power system voltage level
(X/R ratio)
Directional zero sequence overcurrent function is
RCADir is from 0° to 90°
obtained. Typical setting for
depending on the power system earthing (that is,
solidly earthed, earthed via resistor)
Section 6
M13751-254 v3
M13751-263 v5
97