Load Encroachment
·????????Impedance of Heavy load can actually be less than the impedance of some fault. Yet protection must be selective enough to discriminate between load and fault.
·????????Load encroachment occurs only when the impedance crosses the load ability limit of the operating characteristics
·????????Load encroachment is defined as the measured impedance due to load current & voltage exceeding the impedance determined by the load ability limit of the impedance relay at an specific factor.
·????????Load measured by the relay is a function of the direction of power and power factor of load.
·????????Load encroachment can cause an undesired operation of an impedance due to load condition.
·????????Load encroachment uses load blinder characteristics for blocking overreaching of distance elements.
·????????For better load rejection, the traditional lenticular or elliptical shape characteristics can be used. But these characteristics reduces the fault resistance coverage(excludes the load from tripping characteristics).
Manager Contracts || Substation || HV Cables || Smart Metering || Smart Cities || MEP || Renewable
3 年Amir R. how much overloading provision is allowed for load encroachment function which restrains the relay from tripping ?
Senior Protection & Control Engineer @ Siemens Energy UK, MIET (UK)
3 年I think that all zones of line protection must be mentioned and then load encroachment impedance or load blinders must be in between extreme two zones and restrain the relay to operate on overload condition But here question is that for how much time we can overload our transmission line and what would be the impact of transmission transformer
Principal Consultant in TNEI, Manchester
3 年Yes. It is because of enabling the load encroachment function in the relay which restrains the relay from operating.
Project Manager. The Commonwealth of Independent States Project PV Solar power plants in Uzbekistan.
3 年Karthikeyan Sandhanam An excellent article keep it up. It is very relevant for the upcoming Demand Side Response. I love it when someone lays out things in the simplest fashion. Thank you