Auto Recloser’s primary objective is to reduce outage time in distribution lines by providing rapid restorage to power lines. It is done by automatically closing the line after a pre-determined delay. Usually, the temporarily faults would clear themselves in first or second dead time. In case, the fault is of permanent nature the Recloser will enter into lockout state after giving the final closure attempt. After the breaker is in lockout condition, it remain in Open position until it is manually closed by an operator. Auto Recloser duty cycle defined as O-DT1-CO-DT2-CO-DT3-CO-DT4-CO states the event of operation which occur sequentially before the device enter into lockout mode at the end of cycle where, O—Open/trip operation C—Close operation DT1...4– Dead time 1...4
One of the important characteristic of smart grid from conventional grid is the self healing capacity. Auto recloser play a crucial role in this characteristic.
While other characteristics such as cyber-security, real time monitoring and control, interoperability, development of demand response can be realized with our smart Reclosers.
SECTIONALIZER
Sectionalizer are medium/low voltage protective devices which do not require fault interrupting capabilities. It is installed downstream of a MV overhead feeder protected by a recloser/breaker. Sectionalizer count the operations of the backup device during fault conditions. Counts are registered by the Sectionalizer only when fault current flow through the Sectionalizer had been detected prior to the operation of the backup device. After a given number of counts, as selected as a part of the Sectionalizer setting, the Sectionalizer opens to isolate the faulted section of the line when the backup device is in the open position and the section of line where the Sectionalizer is located is in a deenergized state. The objective of the Sectionalizer to remain closed on temporary faults; the backup device will trip and reclose to restore the line to service for such faults prior to the Sectionalizer opening. For permanent faults, the Sectionalizer recognizes that one or more trips have occurred after the backup device reclosed, and it subsequently opens to isolate the faulted portion of the line. our Sectionalizer are programmed to sense the cur-rent & voltage, decide as a fault feed; the upstream protective device operation (opening) is detected by the zero current flow through it and then operates (opens). After the Sectionalizer opens, the backup device automatically recloses to restore to service that portion of the line up to the Sectionalizer location. Application of sectionalizes requires that the backup interrupting device be capable of detecting faults in the Sectionalizer zone of protection.
One of the practical application of Sectionalizer is shown in the above diagram. Two Feeders 1 and 2 and connected through a Sectionalizer which is in normally open condition with voltage sensing provided on both incoming and outgoing sides. Reclosers are provided for the fault interruption while a Sectionalizer is provided at midpoint location for fault isolation. For better understanding, two case scenario are discussed below:
1) For any permanent Fault 1in Zone B, Sectionalizer 1 shall open after preset number of retries from Recloser 1. Finally, Zone B get isolated automatically while supply in Zone A,C and D shall remain active.
2) For any permanent Fault 2 in Zone A, only Recloser 1 shall open and lockout after completing the duty cycle. It is here
when Sectionalizer 3 will sense the voltage outage on one of its side and it will close automatically to restore supply in Zone B. Finally, Zone A will get isolated automatically while supply in Zone B, C and D shall remain active.