Taming the Physical Stress from Fault Current
In a previous blog item, I discussed the benefits newer technologies are affording to expand feeder segmentation through enhanced communication systems and coordination.
However, it is not always possible to deploy the communication infrastructure to support this advanced type of device-to-device coordination because of the speed requirements necessary. It’s particularly problematic, for example, for customers whose terrain and geography interfere with communications.
An alternative approach is to deploy multiple, similarly coordinated advanced fault interrupters that use a circuit-testing procedure that relies on a limited-duration current pulse to test the lines. No high-speed communication system installation is necessary.
Under this new coordination strategy, when the upstream devices respond to the initial fault, they use an advanced fault-hunting technique to test for and find the fault. This is all done in seconds; it’s a very quick response between devices. Once they identify the location of the fault, the device closest to the fault uses the limited-duration current pulse to complete a conventional test sequence, which then determines whether the fault is momentary or sustained.
With the conventional fault-finding techniques, which use time-initiated/high-energy fault testing, every time reclosers close, each device from the substation breaker back to the closing device sees that close as a fault and takes the full brunt of the fault voltage. The limited-duration current pulse technique uses less than 5% of the energy used for a conventional recloser or circuit-breaker test, thus providing a significant enhancement to traditional reclosing, which was introduced in the 1940s.
This better segmented fault isolation saves utilities money because they can more quickly get to the issue and repair it. It also greatly improves customer satisfaction. And a side benefit of this fault-finding technology is that it can be used on non-communicating loop schemes to enable restoration to occur back from a second source to a normally open tie point. There’s no need for any kind of central control or communication for this sectionalizing to occur.
Please feel free to reach out to me to learn more about this technology in the Comments section below.
October 3, 2016