Scope: Primary power path that keeps the shunt reactor energized: HV bus, Line CB, RP-CT, CB Rx, reactor, RN-CT, RG-CT, neutral ground.. The drawing is a shunt reactor protection scheme; the reliability question it supports is availability of the reactor connection.
Boundary: Source = High-Voltage Bus; sink = solid ground at the reactor neutral.. The HV bus is the only source drawn; the reactor current path closes through its grounded neutral, so the ground is the end of the series path.
Can fail: breaker, other. Breakers (Line CB, CB Rx) and the reactor itself are the primary-circuit elements whose failure takes the reactor out of service. CTs are treated as perfect connectors (primary open-circuit failure is very rare); the HV bus and solid ground are boundary references, not failing blocks.
Success: any_path. The reactor is in service if any continuous primary path exists from the HV bus through the reactor to its grounded neutral.
Not modelled:
- Remote-end feed via the Line: The line continues off-drawing; the reactor could also be energized from the remote end, but that source is not shown, so only the local HV bus feed is modelled (Line CB is therefore a series element).
- CCVT (X/Y windings) and all protection relays (87Rx, 67Rx, 71Q, 49, 80Q, 63, 71G): Shunt measurement and protection/secondary equipment, not in the series power path; protection misoperation/failure-to-trip is out of scope.
- Common-mode and protection-induced trips: Not representable in a pure connectivity model.