I'm a grade 10 student in an electrical club. We are studying fire alarm systems and have come to a question.
In an apartment building fire alarm systems, there are isolators (CIMs) and attached to each CIM is a silence module (CSM) for silencing sounders that are installed in each apartment. When the alarm goes off, the silence module has a button that will let the resident silence the sounder for 10 minutes. The building code says that the sound pattern has to be Temporal 3.
Given the datasheets for the isolator/silence modules (CIM/CSM) and using 24 V DC low frequency sounders without strobes, what is the maximum number of sounders that can be on one CSM? (The datasheet shows two sounders.)
Maybe we don't correctly understand the terms in the datasheets, but if the maximum current draw for the sounder (producing Temporal 3) is 138 mA and the output circuit rating of the CIM/CSM is 150 mA maximum at 24 V, then it would seem that only only sounder would be allowed.
Can someone explain? How many sounders maximum can be put safely on the circuit?
Best Answer
It depends on if source is AC or DC for load ratings. Shall see when specs arrive.
I would suggest you choose modules with Temporal loads rated for <=18mA which exist, then the 150mA std output rating can fan out to 8 units.
Update Indeed these do not drive more than one external units. Some have a 1pps Strobe flash with even more load power depending on brightness setting.
I suggest you call/email supplier for interface clarification and alternatives for cost-benefits to suit the requirements.
www.systemsensor.ca/literature/CIM2B.pdf These are 18mA