Configuration and Setting of Protection Relays or Numeric Relays

The quest for performance, security and reliability as tools for preventing blackouts, has led to the wide spread use of numerical protection relays. Numerical relays have gone a long way to meeting the challenges for security, reliability, performance and compactness. However, numerical relays by necessity embody a level of complexity and sensitivity, not encountered with previous protection devices. This paper reviews some of the problems associated with the use of numerical protection relays which have caused maloperation of protection and even system blackouts;, in this way the reader can eliminate some of the known problems before they become a concern on their system.