Auto-Reclosing onto a permanent fault, one can arrange to combine Auto-Reclosing witha synchronism check on line terminals close to such power stations and attempt energizingfrom the side furthest away from the power station and perform the synchronism check atthe local end if the energizing was successful.Transmission protection systems are usually sub-divided and provided with tworedundant protection IEDs. In such systems it is common to provide auto-reclosing in onlyone of the sub-systems as the requirement is for fault clearance and a failure to reclosebecause of the auto-recloser being out of service is not considered a major disturbance. Iftwo auto-reclosers are provided on the same breaker, the application must be carefullychecked and normally one must be the master and be connected to inhibit the other auto-recloser if it has started. This inhibit can for example be done from Autorecloser for 3-phase operation(SMBRREC ,79) In progress.A permanent fault will cause the line protection to trip again when it recloses in an attemptto clear the fault.The auto-reclosing function allows a number of parameters to be adjusted.Examples:• number of auto-reclosing shots• auto-reclosing open times (dead time) for each shot11.2.2.1 Auto-reclosing operation OFF and ONOperation of the automatic reclosing can be set OFF and ON by a setting parameter andby external control. Parameter Operation= Disabled, or Enabled sets the function OFFand ON. In setting Operation=ExternalCtrl, OFF and ON control is made by input signalpulses, for example, from the control system or from the binary input (and other systems).When the function is set ON and operative (other conditions such as CB closed and CBReady are also fulfilled), the output SETON is activated (high). When the function isready to accept a reclosing start.11.2.2.2 Initiate auto-reclosing and conditions for initiation of a reclosing cycleThe usual way to start a reclosing cycle, or sequence, is to start it at tripping by lineprotection by applying a signal to the input RI. Starting signals can be either, General Tripsignals or, only the conditions for Differential, Distance protection Zone 1 and Distanceprotection Aided trip. In some cases also Directional Ground fault function Aided trip canbe connected to start an Auto-Reclose attempt.A number of conditions need to be fulfilled for the start to be accepted and a new auto-reclosing cycle to be started. They are linked to dedicated inputs. The inputs are:Section 11 1MRK 506 334-UUS AControl306Application manual
