The pole mounted CB to be used is an Intellirupter from S&C Electric, along with a custom designed frame which will be provided to allow it to be installed underneath live ABSs from ground level. Final connections to the overhead line will be made with the line still energized, using hot stick techniques and live line connectors. The CB has an integrated disconnecting switch which can be observed to be open during connection and disconnection operations which along with suitable parking bars for live line connectors, removes the need to incorporate earth switches either side of the CB to make it safe during the erection and removal process. The CB also has capacitive voltage sensing transducers on both sides of the CB and on all phases which can be used to ensure that the phase rotation is the same on both sides of the circuit breaker, prior to starting the synchronising process.
The CB will be connected in parallel with the open ABS and then transmit the relevant data on voltage and frequency from both sides of the CB and the phase angle difference between the two sides to a lap top computer using a wireless communications link. This will present the user with a simplified synchroscope and allow the user to give directions to the operators of the generating units to speed up or slow down the generators and to adjust the voltage on the islanded network to provide the right conditions to allow the island network to be re-synchronised back on to the main network.
When conditions are correct then the lap top will be used to provide a close instruction to the CB via the wireless link. When the CB is closed the ABS can then safely be closed and the CB removed from the circuit using live line techniques from ground level.
This will mean that customer supplies do not need to be interrupted to connect or disconnect temporary generation.
Benefits
Determine the technical and operational viability of the proposed methodologyQuantify the savings in CIs and CHLs which could be saved by the use of this techniqueDetermine the commercial viability of applying this methodology across the SHEPD and SEPD license areas.
