Distance functions perform a very important and essential part of many power system protective relaying systems. This book discussed possible problem areas that can be encountered in the design and application of distance type function. It is the responsibility of the manufacturer to design relays,and to aid in their application, with these problems in mind. However, it is the ultimate responsibility of the user to insure that the relays are applied correctly. PSCAD/EMTDC, is a powerful electromagnetic time domain transient simulation environment and study tool to model Network. Simulations carried out under conditions of fault and power swing to study the behavior of Quadrilateral relay under power swing.A technique proposed can applied evaluate its effectiveness in blocking the trip signals during power swing and fault clearance.