12.2.2.17 Transient faultAfter the Reclosing command the reset timer keeps running for the set time. If no trippingoccurs within this time, tReset, the Auto-Reclosing will reset. The CB remains closed andthe operating gear recharges. The input signals 52a and CBREADY will be set12.2.2.18 Permanent fault and reclosing unsuccessful signalIf a new trip occurs, and number of reclosing shots is set to 1, a new input signal RI orTRSOTF appears, after the CB closing command, the output UNSUCCL (unsuccessfulclosing) is set high. The timer for the first shot can no longer be started. Depending on theset number of Reclosing shots further shots may be made or the Reclosing sequence isended. After reset timer time-out the Auto-Reclosing function resets, but the CB remainsopen. The “CB closed” information through the input 52a is missing. Thus, the reclosingfunction is not ready for a new reclosing cycle.Normally, the signal UNSUCCL appears when a new trip and start is received after the lastreclosing shot has been made and the auto-reclosing function is blocked. The signal resetsafter reset time. The “unsuccessful” signal can also be made to depend on CB positioninput. The parameter UnsucClByCBChk should then be set to CBCheck, and a timertUnsucCl should be set too. If the CB does not respond to the closing command and doesnot close, but remains open, the output UNSUCCL is set high after time tUnsucCl. TheUnsuccessful output can for example, be used in Multi-Breaker arrangement to cancel theauto-reclosing function for the second breaker, if the first breaker closed onto a persistentfault. It can also be used to generate a Lock-out of manual closing until the operator hasreset the Lock-out, see separate section.12.2.2.19 Lock-out initiationIn many cases there is a requirement that a Lock-out is generated when the auto-reclosingattempt fails. This is done with logic connected to the in- and outputs of the Autoreclosefunction and connected to Binary IO as required. Many alternative ways of performing thelogic exist depending on whether manual closing is interlocked in the IED, whether anexternal physical Lock-out relay exists and whether the reset is hardwired, or carried outby means of communication. There are also different alternatives regarding what shallgenerate Lock-out. Examples of questions are:• Shall back-up time delayed trip give Lock-out (normally yes)• Shall Lock-out be generated when closing onto a fault (mostly)• Shall Lock-out be generated when the Autorecloser was OFF at the fault or forexample, in Single phase AR mode and the fault was multi-phase (normally not as noclosing attempt has been given)• Shall Lock-out be generated if the Breaker did not have sufficient operating power foran auto-reclosing sequence (normally not as no closing attempt has been given)1MRK 505 337-UUS - Section 12Control311Application manual
