fire alarm system

An isolator fault module is a device that is used when one wishes to "compartmentalize" a fire alarm system such that a fault (wire break, wire short, field module catastrophic failure) at one point in the system does not disable the entire system. These devices are most often used in high-rise or very large buildings. A typical scenario is a data (communication) pair is run from the ground floor up to the top floor (riser). At each floor, a tap is made into this riser pair. The first device on the floor is an isolator module, which then feeds to all other devices on that floor. Thus, if any floor has a system failure, the isolator module for that floor "clamps" the data pair at that point and does not allow the remainder of the system to be affected. Additionally, the isolator module will transmit to the main fire alarm panel that that particular floor is down.

NFPA 72 will tell you all you need (or want) to know about fire alarm systems. Regarding specific manufacturers systems, you will need to get a specific system manual. Good luck with that one however, as they are considered trade secrets.