Hochiki Plant Control Module, 4 Relay Outputs, 4 Inputs, Loop Powered CHQ-PCM(SCI)

What this module does

A fire alarm often needs to do more than sound. This Hochiki module lets the panel act on other equipment, such as closing dampers or shutting plant down, and it brings local signals back in.

It sits on the loop like any other addressed device. It takes its power from there too, with one address covering all four relays and all four inputs.

How it works

• Volt free contacts: Volt free means the relay supplies no power of its own. It simply opens or closes a circuit that your equipment provides.
• Monitored inputs: an end of line resistor lets the module check each input's wiring for an open or short circuit. The thresholds in the specifications show how it tells these apart from a real signal.
• Short-circuit isolator: As a rule, an isolator cuts off a shorted section of loop so that the rest can keep running.

What the figures mean in practice

• Loop load: the polling current applies each time the unit is polled, so include it when adding up what the panel's loop has to supply.
• Resistive load: the relay rating is for a resistive load. As a rule, motors and coils are harder on contacts, so check any inductive load with care.
• Input threshold: the 470 Ω value activates an input. The operational resistor for this is among those supplied, so do not discard them.

Installing it

• Handling: suitable anti-static precautions must be taken, so keep the board in its packaging until you are ready.
• Address first: set the address before fixing the unit, then write it down for the commissioning record.
• Heavy cables: for heavy cables Hochiki recommends the SMB-1 Module Enclosure with the SMB-ADAPTOR plate. Check what else that plate needs before ordering.

Planning your system

Where dust or water protection matters, the CHQ-BACKBOX raises the rating to IP65 and adds to the overall height.

Before ordering, confirm the panel supports this module. It sits among other fire alarm modules and interfaces, and the commercial fire alarm systems guide explains why the panel protocol comes first.

Think about what each relay does during a power-up too. Because the contact state is indeterminate until powered, agree with the plant engineer what should happen at that moment.