In Tricon Manual, there are Logic Power and Field Power. Who can tell me the difference? Thanks!

 

Like other PLCs, Tricon has chassis power supply (which is redundant in configuration)and separate power supply (may be redundant or N+1 configuration as engineered)for field devices.

Individual modules in a chassis are exposed to both powers as chassis power supplies are to power up the module through back plane where as interrogating supplies of field power unit is looped through the modules to get sense inputs or deliver outputs.

"Logic power" refers to number and type of modules supported per chassis with hot slot configuration without being overloaded. It is typically limited to 175 watts as each chassis power supply units deliver this power as maximum at rated 60 degC. This is with the assumption that only one power supply module is in operation.

"Field power" is the percentage of field circuit power that is dissipated within the chassis. This is required in unison with "logic power" to identify total heat load dissipated by a tricon chassis. Total cooling requirement is calculated based on above heat load and a desired ambient temperature of 40 degC around chassis.

Hence, logic power is a restrictive guide to chassis configuration whereas, logic +field power identifies total heat load and final cooling requirement.

Regards.