Foxboro PSS 21H-2X66 B4 G66 Tricon Termination Enclosure

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.

Power Distribution Architecture

The enclosure provides a redundant 24 V power system using two FPS480-24 power

supplies fed by independent sources. Power wiring is routed through the bottom of the

enclosure. The input power connects to the primary and secondary entry terminal

blocks for main and backup power.

Electrical fuses are monitored by the Fuse Monitoring Unit (FMU) and an open fuse

indication from the FMU is wired into the Enclosure Monitoring Unit (EMU) through the

Alarm Distribution Assembly.

Grounding

All enclosure structural elements are integrally grounded by the enclosure design to

meet the appropriate industry regulations and standards. The enclosure is equipped

with two instrument earth bars. It also has a protective connection point at the outside

bottom of the enclosure for customer grounding purposes. Field wiring shields can be

terminated either to the Terminal Assemblies or to the instrument ground bus bar.

Spare signal wires and shields can be terminated either to the Terminal Assemblies or

to the instrument ground bus bar.