Application of mho and quadrilateral distance characteristics in power systems [relay protection]

Distance relay elements can be designed to conform to a number of different operating criteria-plain impedance, reactance, mho and polygonal characteristics can be supplied. Today, many manufacturers offer a choice of either circular (mho) or quadrilateral (quad) characteristics. However, many users are uncertain as to which to specify and a full understanding of the advantages and disadvantages of each characteristic related to fault type and system conditions is desirable.