You're right to be curious about the similarities! Let's break it down

Understanding the Graphs
Circuit Breaker Curve (Your PDF)

This graph shows the clearing time (how long it takes to interrupt the current) versus the prospective fault current (the fault current the circuit would experience if the breaker wasn't there). It also includes a key point: how much it limits the peak let-through current.

Fuse Curve (Your JPG)

This graph focuses more directly on the let-through current. It shows both the prospective fault current (available short-circuit current) and the let-through current (the peak current that the fuse actually allows to pass before interrupting the circuit). The A-B line, as you noted, is a significant feature of this graph.

Comparing the Lines Circuit Breaker's "Maximum available peak current at 15% Power Factor" Line

This line represents the theoretical maximum peak current that could flow if the circuit breaker did absolutely nothing to limit the current. It is often calculated with a low power factor to represent the worst-case fault condition (high inductance). Essentially, it's the peak of the first half-cycle of the fault current without any interruption.

Fuse's A-B Line

This line represents the peak current that the fuse will permit through it when subjected to different available short-circuit currents.

The Similarity (and the Important Difference) Conceptual Similarity

Both lines represent the peak current associated with the fault. The key is what happens after that peak.

The Key Difference: Interruption

The

Circuit Breaker line is a maximum available peak. The breaker will interrupt the current (hopefully) well before that current can sustain itself. The actual let-through current from the breaker will be below this line, as indicated by the region on the graph for current limiting breakers. The Fuse's A-B line directly shows you the Peak Let Through Current from the fuse. This is the actual current you have to account for when sizing other components, coordination, etc.

In short

The A-B line of the current-limiting fuse shows the actual peak let-through current. The peak available current line for the breaker indicates the maximum amount of current that could be seen in a prospective fault condition with no protection. The breaker, if performing as expected, should interrupt the current below that value, and the breaker's performance lies somewhere within the area that shows the maximum peak let-through current.

Analogy

Think of it like this:

Circuit Breaker "Maximum available peak current at 15% Power Factor" Line

This is like saying "If there's no speed limit, a car could reach 150 mph."

Fuse's A-B Line

This is like saying "The speed governor on the car limits the top speed to 80 mph."

Therefore, to specifically answer your question:

No, the circuit breaker "Maximum available peak current at 15% Power Factor" line is not the same as the A-B line on a fuse curve. The A-B line represents the let-through current. The circuit breaker line represents the theoretical maximum unlimited current. The actual let-through current performance for the current limiting breaker lies in the area shown on the graph. Flag for review