Foxboro ISA-S71.04-1985 Environmental Conditions for Process Measurement and Control Systems

Heat from the equipment mounted within the enclosure is convected naturally and is

dissipated by the exterior surfaces of the enclosure. For operating in ambient

temperatures up to 55° C (131° F), natural convection is supplemented by two

redundant fans that circulate air within the sealed enclosure.

The fans and temperature within the enclosure are monitored by the Enclosure

Monitoring Unit (EMU) that provides a diagnostic alarm on fan deterioration or

enclosure over temperature.

Leave a minimum of 150 mm(6 in) space between adjacent cabinets or a cabinet and

a wall, to allow the flow of air to cool the cabinet.

Cable Entry

Bottom cable entry for power, communication, and field cables is through customer

supplied cable glands that maintain the enclosure protection classification, or optional

factory fitted Multi Cable Transit (MCT).

Modular Baseplate Mounting

The enclosure contains two 8-position standard 200 Series modular baseplates for

Foxboro DCS Fieldbus Modules (FBMs), and two 2-position baseplates for the

FCM2F10s. These are mounted on two vertical DIN rails as shown in Figure 1. page

7. The FBMbaseplates include signal connectors for the FBMs, redundant

independent DC power connections, system cable connections, module fieldbus

connections, and time synchronization connections.

For more information on the modular baseplates, see Standard 200 Series

Baseplates (PSS 41H-2SBASPLT).

Field Termination Assemblies

Termination Assemblies (TAs) are installed on the DIN rails mounted at the sides of

the FBM baseplates. The Universal I/O modules are connected to the TAs with pre

installed system cables.

The TAs are supplied with redundant 24 V DC, protected by fuses that are monitored

by the Fuse Monitoring Unit (FMU).

The enclosure is shipped with TAs fitted with passive feed-through signal conditioners

which you can replace with the signal conditioners listed in the section Termination

Assemblies and Signal Conditioners, page 8.