Which alarm might appear on an annunciator panel from an EHV breaker?

The appearance of a low air pressure alarm on an annunciator panel from an Extra High Voltage (EHV) breaker is significant because many circuit breakers, particularly those with pneumatic mechanisms, rely on air pressure to operate correctly. When air pressure drops below a set threshold, it can indicate a potential malfunction, leading to insufficient force to operate the breaker and potentially causing safety issues or equipment failure.

Each of the other options represents different issues that may arise in electrical systems, but they are not directly tied to the operation of the EHV breaker's mechanism. High current flow pertains to the amount of current passing through the system, which, while critical, typically does not trigger an alarm on the same system controlling air pressure. Excessive voltage could signify a problem in the system but is usually monitored in different ways. Increased pump temperature relates to the operation of cooling systems or pumps but does not directly affect the EHV breaker mechanism itself. Thus, low air pressure specifically highlights a crucial aspect of the EHV breaker's operational readiness and safety.