US 12,407,184 B2
Distribution line ground fault prevention with blown fuse protection on single phase
Robert B. Stuart, San Tan Valley, AZ (US)
Assigned to Milo Group LLC, Casper, WY (US)
Filed by Robert B. Stuart, San Tan Valley, AZ (US)
Filed on Nov. 4, 2024, as Appl. No. 18/936,543.
Application 18/936,543 is a continuation in part of application No. 18/920,865, filed on Oct. 19, 2024.
Application 18/920,865 is a continuation in part of application No. 18/464,596, filed on Sep. 11, 2023, abandoned.
Application 18/464,596 is a continuation in part of application No. 18/448,914, filed on Aug. 12, 2023, abandoned.
Application 18/448,914 is a continuation in part of application No. 18/064,152, filed on Dec. 9, 2022, granted, now 11,852,692, issued on Dec. 26, 2023.
Prior Publication US 2025/0062639 A1, Feb. 20, 2025
Int. Cl. H02J 13/00 (2006.01); H02J 3/00 (2006.01)
CPC H02J 13/0004 (2020.01) [H02J 3/0012 (2020.01); H02J 13/00002 (2020.01)] 14 Claims
OG exemplary drawing
 
1. A system for preventing ground fault or other short circuit in an electric distribution line system, caused by a break in a line, utilizing programmable relay protection in a plurality of relay devices programmed to monitor high sensitivity parameters, which includes blown fuse protection in a single phase tap line to prevent false operation of the open conductor logic when a tap line fuse successfully interrupts a short circuit on the tap line, which comprises:
a blown fuse protection subsystem having a tap line with a plurality of current transformers on said tap line with a plurality of relay devices functionally connected to said transformers by being connected to secondary stepdown windings of said current transformers, said relay devices being for monitoring high sensitivity parameters on said tap line, said devices being relay devices for said tap line, having a housing, and each said relay device having connections with an incoming line and an outgoing line for connection to current transformers on said tap line, and having a plurality of monitors, and having a programmable microprocessor functionally connected to said monitors, said programmable microprocessor being-programmed for micro-monitoring segments of said tap line as follows: to detect changes in negative sequence overcurrent on said single phase tap line, to calculate the change in negative sequence overcurrent, to store a preset acceptable range for change of negative sequence overcurrent, to compare said calculated change in negative sequence overcurrent to said preset acceptable range for change of negative sequence overcurrent, and further programmed to perform the following process:
a) if there is a signal indicating a potential line break fault from the high sensitivity monitoring and, if the calculated change in negative sequence overcurrent is within said preset acceptable range for change of negative sequence overcurrent, then there is no blown fuse, and the blown fuse protection subsystem signals to permit said high sensitivity monitoring to proceed to signal a true broken conductor for line shut down of said tap line; and,
b) if there is a signal indicating a potential line break fault from the high sensitivity monitoring and, if the calculated change in negative sequence overcurrent is outside said preset acceptable range of change of negative sequence overcurrent, then there is a blown fuse, and the high sensitivity monitoring does not proceed to signal a true line break fault for line shut down of said tap line.