What does a trouble signal indicate in a fire alarm system?

A trouble signal in a fire alarm system serves to alert users that there is an issue affecting the functionality of the system. This could range from a variety of potential malfunctions, such as issues with wiring, devices that are not communicating properly, or problems with power supply, including low battery conditions. The presence of a trouble signal indicates that while the system may still be able to monitor for emergencies, it is not functioning at full capability, which can compromise safety.

Understanding the role of a trouble signal is crucial for maintenance and safety compliance, as it emphasizes the need for prompt investigation and resolution of any indicated issues to ensure the system can effectively perform its life-saving function. The other options suggest complete operational status or component performance, which is contradictory to the purpose of a trouble signal, as such signals specifically denote a deviation from normal operations.