When the protection trips, the initiation of autoreclosing shots is in most applications executed with the INIT_1...6 inputs. The DEL_INIT2...4 inputs are not used. In some countries, starting the protection stage is also used for the shot initiation. This is the only time when the DEL_INIT inputs are used.
In total, the AR function contains six separate initiation lines used for the initiation or blocking of the autoreclosing shots. These lines are divided into two types of channels. In three of these channels, the signal to the AR function can be delayed, whereas the other three channels do not have any delaying capability.
Each channel that is capable of delaying a start signal has four time delays. The time delay is selected based on the shot pointer in the AR function. For the first reclose attempt, the first time delay is selected; for the second attempt, the second time delay and so on. For the fourth and fifth attempts, the time delays are the same.
- Str 2 delay shot 1
- Str 2 delay shot 2
- Str 2 delay shot 3
- Str 2 delay shot 4
- Str 3 delay shot 1
- Str 3 delay shot 2
- Str 3 delay shot 3
- Str 3 delay shot 4
- Str 4 delay shot 1
- Str 4 delay shot 2
- Str 4 delay shot 3
- Str 4 delay shot 4
Normally, only two or three reclosing attempts are made. The third and fourth attempts are used to provide the so-called fast final trip to lockout.
Delayed DEL_INIT_2...4 signals are used only when the autoreclosing shot is initiated with the start signal of a protection stage. After a start delay, the AR function opens the circuit breaker and an autoreclosing shot is initiated. When the shot is initiated with the trip signal of the protection, the protection function trips the circuit breaker and simultaneously initiates the autoreclosing shot.
If the circuit breaker is manually closed against the fault, that is, if SOTF is used, the fourth time delay can automatically be taken into use. This is controlled with the internal logic of the AR function and the Fourth delay in SOTF parameter.
A typical autoreclose situation is where one autoreclosing shot has been performed after the fault was detected. There are two types of such cases: operation initiated with protection start signal and operation initiated with protection trip signal. In both cases, the autoreclosing sequence is successful: the reclaim time elapses and no new sequence is started.
The autoreclosing shot is initiated with a start signal of the protection function after the start delay time has elapsed. The autoreclosing starts when the Str 2 delay shot 1 setting elapses.
The autoreclosing shot is initiated with a trip signal of the protection function. The autoreclosing starts when the protection operate delay time elapses.
Normally, all trip and start signals are used to initiate an autoreclosing shot and trip the circuit breaker. ACTIVE output indicates reclosing sequence in progress. If any of the input signals INIT_X or DEL_INIT_X are used for blocking, the corresponding bit in the Tripping line setting must be FALSE. This is to ensure that the circuit breaker does not trip from that signal, that is, the signal does not activate the OPEN_CB output. The default value for the setting is "63", which means that all initiation signals activate the OPEN_CB output. The lowest bit in the Tripping line setting corresponds to the INIT_1 input, the highest bit to the INIT_6 line.