(a) What is a high impedance relay and when is it used?
(b) A motor with differential protection has a full load currentof 200 A. When starting, the motor takes 5 × FL current. The motoris remote from the switchgear which houses one set of CTs and therelay. If the CT ratios are 200/1, the secondary winding resistanceis 1.0 ohm and the protection loop lead resistance to the motor is6 ohms, calculate the minimum relay setting voltage. State what theCT knee point voltage should be.
