VON MODEL SST15-832 ARC REFLECTION SECTIONALIZING SYSTEM Page 9
beginning of the faulted cable. This eliminates the need to subtract the apparent lead
length from the distance shown. The right marker is normally adjusted to the location
of the fault to give the distance to the fault from the hook up location. Distance
measurements are displayed in the lower left portion of the display which represent
the distance between the left marker and the right marker.
8.
Push the
STOP
button to discharge the cable and the internal capacitor.
9.
Use the distance indicated to determine which section the fault is in.
VI-F SECTIONALIZING URD LOOP SYSTEMS
The arc reflection system is a method for determining the faulted cable section in a loop
without using fuses and subjecting the system to excessive fault currents or opening each
transformer cabinet to inspect fault indicators. By connecting the SST15-832 at the open
cutout or at a center transformer cabinet the operator can determine the distance to the
cable fault using the radar. Then the faulted cable section can be disconnected and all
customers can be returned to service. When all customers are returned to service the
SST15-832 can then be connected to the faulted cable and the distance to the fault
determined using traditional methods.
Some customers have expressed concerns that putting an arc reflection pulse on the
source side or transformers feeding customers would send damaging pulses into the
customers system. Only a small percent of the energy can go through the transformer.
Since the SST15-832 is rated 60 watts and typically the customers connected are
attempting to pull many thousands of watts there is no way that damaging pulses can get
into the customers system.
Currently the most popular approach to sectionalizing using an arc reflection system is to
open a transformer halfway between the pole and the open point. The arc reflection system
is then connected to both pieces of the circuit one at a time to determine where the fault is
located. If both traces are identical on a run then it does not have a fault and can be
refused. The arc reflection system will not locate internal transformer failures so if the fuse
blows each transformer in that section should be inspected for failure. The arc reflection
system should be connected to the second section and impulsed using the “START” button.
The low voltage radar pulses alone can be used to verify that the faulted cable has been
disconnected from the system so that power can be restored to the customers.
Summary of Contents for SST15-832
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