Energex supplies approximately 1.3 million customers in South East Queensland covering an area of 25,000 square km and are constantly looking for means of increasing network performance.
Commencing in 2003/04 financial year Energex installed approximately 50 Noja Power Switchgear’ s OSM automatic circuit reclosers (ACR's) on predominantly its urban network.
In the majority of cases a single recloser was placed at the half-way point along the backbone or main trunk of the feeder. In a small number of cases, the ACR was placed on one or both feeder legs at the substation of double cable box feeders.
This program represented a relatively small number of feeders out of a total population of around 1000 urban feeders. The majority (70%) of the 50 ACRS were installed and commissioned by 31 Jan 2004, with the rest installed in 2004/05 and 2005/06.
This group of feeders supplies around 65,000 customers and has a total installed circuit exposure of 290 urban km and 460 rural km. This equates to approximately 5% of Energex's total customer base and around 4.5% of the circuit length of the urban network and around 3% of the rural network.
For the period since commissioning to December 2006, there have been 101 faults beyond the reclosers due to all causes (non-storm and storm events).
16 of these events occurred during severe weather for which a major event day (MED) exclusion was granted. 32 out of the 50 feeders with the installed ACR had an outage during this period. Out of the 32 feeders, half of the feeders accounted for around 75% of the faults.
The estimated SAIDI saving for the period is 4.8 minutes excluding MEDs.
The total SAIDI saving with all events included is 11.4 minutes. This saving is estimated by theoretically calculating the impact of the fault with and without the ACR installed.
Following the initial 50 Noja Power OSM's a further 70 ACR's were purchased and installed.