r_20261029_184052_2c67

done

drawing: Sample3.png
reference: none
at: 2026-10-29T18:40:52Z

Review

If these are right, every cut set is right: the cut sets are computed from the paths and what can fail.

1 · Power reaches the load by these paths

Click a path to light it up on the drawing. Is every part on that route boxed, and nothing extra?

Path 1 7 parts: B71 → CB7-1 → CBRX → B7RX → Three Phase Rx → BNRX → Neutral Rx Path 2 7 parts: B72 → CB7-2 → CBRX → B7RX → Three Phase Rx → BNRX → Neutral Rx No route is missing: every way power can flow on the drawing lights up in some path.

2 · Parts not on the drawing

1 added: 765kV System. Each one belongs (see Not on the drawing).

3 · Assumptions

Can fail: breaker, busbar, other Success: the supply is OK if at least 1 of the 2 paths works Boundary: Source = 765 kV system behind Bus 1 and Bus 2. Sink = reactor neutral grounded (reactor in service). Not modelled: Spare Phase Rx and Spare Neutral Rx; Protection relays (87RXA/O, 87RXB/*, 63/71G/71Q/49), CTs and CCVTs; The outgoing line; Common-cause failures and switching time

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Summary

Single points of failure

5 components: if any one of these fails on its own, the supply is lost.

{B7RX}
{BNRX}
{CBRX}
{Neutral Rx}
{Three Phase Rx}

Pairs

4 pairs: the supply is lost only if both components of a pair fail together.

{B71, B72}
{B71, CB7-2}
{B72, CB7-1}
{CB7-1, CB7-2}

Click a set to highlight its components on the drawing and in the block diagram; click it again to clear.

Drawing and graph

block (can fail)perfect connectorin a cut-set difference show all connections

Hover a box to see its own connections.

Page 1

Not on the drawing

node	type	connected to	why
`765kV System`	source	B71, B72	Virtual source representing the 765 kV grid behind Bus 1 and Bus 2; drawing shows only the bus stubs.

Block diagram

Series runs left to right; parallel branches stack.

Run r_20261029_184052_2c67 · from Sample3.png · 9 blocks · 5 single points of failure. Drawn in BlockSim's RBD layout so it can be rebuilt there block for block; this is a picture, not a BlockSim file. The machine-readable export is the Open-PSA fault tree.

Nested view

B71→CB7-1

B72→CB7-2

→CBRX→B7RX→Three Phase Rx→BNRX→Neutral Rx

Cut sets

Reference: none

No verdict: nothing was compared with a reference. These are the model's own cut sets.

This model

Minimal cut sets up to order 3. Click an order to show or hide it.

Order 1 (5)

{B7RX}
{BNRX}
{CBRX}
{Neutral Rx}
{Three Phase Rx}

Order 2 (4)

{B71, B72}
{B71, CB7-2}
{B72, CB7-1}
{CB7-1, CB7-2}

Gaps

Spare Phase Rx / Spare Neutral Rx The drawing shows the spare reactor connected to B7RX and BNRX with no switching device. I can't tell whether it is energised in normal service (which would add redundancy) or only a hand-swapped spare, so I modelled it as not in service.
CB7-1 / CB7-2 / Line tap The drawing doesn't show whether the arrangement is breaker-and-a-half or ring, or what is beyond the line. I assumed both buses are energised and both breakers are normally closed.

Assumptions

Scope: Primary power path that keeps the 765 kV shunt reactor energised: Bus 1/Bus 2, CB7-1/CB7-2, CBRX, B7RX, Three Phase Rx, BNRX, Neutral Rx.. The drawing is a reactor protection SLD, so reactor availability is the natural reliability question.

Boundary: Source = 765 kV system behind Bus 1 and Bus 2. Sink = reactor neutral grounded (reactor in service).. The reactor can be fed from either bus through CB7-1 or CB7-2, and its circuit is only complete through the neutral reactor to ground.

Can fail: breaker, busbar, other. Breakers, buses and the reactors (phase and neutral) are the primary equipment whose failure takes the reactor out. CTs, VTs and relays are protection/metering only and are left out. The line tap node is just a conductor junction, so it is a perfect connector. The source and sink are virtual.

Success: any_path. The reactor is in service if any closed path exists from the 765 kV system through a bus breaker, CBRX, the phase reactor and the neutral reactor to ground.

Not modelled:

Spare Phase Rx and Spare Neutral Rx: These are spare units. They are swapped in by hand after a failure, so they are not treated as running in parallel.
Protection relays (87RXA/O, 87RXB/*, 63/71G/71Q/49), CTs and CCVTs: These are secondary systems. Failure-to-trip and spurious-trip modes are outside this connectivity model.
The outgoing line: The line runs off the page and is not on the path to the reactor.
Common-cause failures and switching time: Only independent failures in a static any-path model.