8.4.3.10 Setting of minimum operate currents SEMOD154469-132 v5The operation of the distance function will be blocked if the magnitude of thecurrents is below the set value of the parameter IMinOpPP and IMinOpPE.The default setting of IMinOpPP and IMinOpPE is 20% of IBase where IBase isthe chosen base current for the analog input channels. The values have been provenin practice to be suitable in most of the applications. However, there might beapplications where it is necessary to increase the sensitivity by reducing theminimum 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.8.4.3.11 Setting of directional mode SEMOD154469-176 v3Setting of the directional mode is by default set to forward by setting the parameterDirMode to Forward.The selection of Offset mho can be used for sending block signal in blockingteleprotection scheme, switch onto fault application and so on.The Reverse mode might be use in comparison schemes where it is necessary toabsolute discriminate between forward and reverse fault.8.4.3.12 Setting of direction for offset mho SEMOD154469-181 v3If 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 characteristicwill be cut off by the directional lines used for the mho characteristic. The setting isby default set to Non-Directional.8.4.3.13 Setting of timers for distance protection zones SEMOD154469-138 v7The required time delays for different distance protection zones are independent ofeach other. Distance protection zone 1 can also have a time delay if so required forselectivity reasons. One can set the time delays for all zones in a range of 0 to 60seconds. The tripping function of each particular zone can be inhibited by settingthe corresponding Operation parameter to Off.Different time delays are possible for the phase-to-earth tPE and for the phase-to-phase tPP measuring loops in each distance protection zone separately, to furtherincrease the total flexibility of a distance protection.In the case of evolving faults or momentary current transformer saturationconditions, the pick up of the zones may get delayed. Zone timer logic improvesthe operating time in such conditions. The zone timer logic can be set using theSection 8 1MRK 506 369-UEN BImpedance protection260 Line distance protection REL670 2.2 IECApplication manual
