| 摘要 |
<p>In the field of current differential protection relays there is a need for improvements in or relating to the protection relays to allow them to accommodate current transformer saturation while maintaining a desired degree of reliability. A method of operating a current differential protection relay (10, 26) following a fault, the protection relay (10, 26) being electrically coupled to a protection zone of an electrical power system, comprises the steps of establishing a fault condition by discriminating between an internal fault inside the protection zone and an external fault outside the protection zone; and modifying the sensitivity of the protection relay (10, 26) according to the nature of the fault condition. A current differential protection relay (10, 26) comprises a fault discriminator module (20) to establish a fault condition by discriminating between an internal fault inside a protection zone of an electrical power system and an external fault outside the protection zone; and a sensitivity modifying module (22) to modify the sensitivity of the protection relay according to the nature of the fault condition.</p> |
