ABB Relion 670 series - Load Impedance Limitation, with Load Encroachment Function Activated; Setting of Direction for Offset Mho; Setting of Directional Mode; Setting of Minimum Operate Currents

8.4.3.8 Load impedance limitation, with load encroachment function activated
The parameters for load encroachment shaping of the characteristic are found in the
description of Faulty phase identification with load encroachment for mho (FMPSPDIS),
refer to section
"Load encroachment characteristics".
8.4.3.9 Setting of minimum operate currents
The operation of the distance function will be blocked if the magnitude of the currents is
below the set value of the parameter IMinPUPP and IMinPUPG.
The default setting of IMinOpPP and IMinPUPG is 20% of IBase where IBase is the
chosen base current for the analog input channels. The values have been proven in practice
to be suitable in most of the applications. However, there might be applications where it
is necessary to increase the sensitivity by reducing the minimum operate current down to
10% of IBase.
The minimum operate fault current is automatically reduced to 75% of its set value, if the
distance protection zone has been set for the operation in reverse direction.
8.4.3.10 Setting of directional mode
Setting of the directional mode is by default set to forward by setting the parameter
DirModeSel to Forward.
The selection of Offset mho can be used for sending block signal in blocking teleprotection
scheme, switch onto fault application and so on.
The Reverse mode might be use in comparison schemes where it is necessary to absolute
discriminate between forward and reverse fault.
8.4.3.11 Setting of direction for offset mho
If offset mho has been selected, one can select if the offset mho shall be Non-Directional,
Forward or Reverse by setting the parameter OfffsetMhoDir.
When forward or reverse operation is selected, then the operation characteristic will be cut
off by the directional lines used for the mho characteristic. The setting is by default set to
Non-Directional.
8.4.3.12 Setting of timers for distance protection zones
The required time delays for different distance protection zones are independent of each
other. Distance protection zone 1 can also have a time delay if so required for selectivity
reasons. One can set the time delays for all zones in a range of 0 to 60 seconds. The tripping
1MRK 506 369-UUS - Section 8
Impedance protection
Line distance protection REL670 2.2 ANSI 277
Application manual