FOXBORO FBM202 Evo™ Process Automation System

FOXBORO FBM202 Evo™  Process Automation  System

OVERVIEW

The FBM202 Thermocouple/mV Input contains eight thermocouple input channels, and one isolated RTD reference junction compensation channel (for terminal temperature sensing). Each thermocouple/mV channel accepts standard thermocouples for various temperature ranges, and each provides thermocouple burnout detection (up-scale). The inputs are galvanically isolated from other channels and ground.

The module performs the signal conversion required to interface the electrical input signals from the field sensors to the optionally redundant Fieldbus. It executes an Analog Input application program, which provides integration time and Rate of Change Limits configurable options.

FEATURES

Key features of the FBM202 are: 

 Eight channels for input of thermocouple signals 

 One isolated RTD reference junction compensation channel (for terminal temperature sensing) 

 Each input channel is galvanically isolated

 Rugged design suitable for enclosure in Class G3 (harsh) environments 

 Execution of an analog input application program that provides conversion time and configurable options for Rate of Change Limits 

 High accuracy achieved by sigma-delta data conversions for each channel 

 Termination Assemblies (TAs) for locally or remotely connecting field wiring to the FBM202

HIGH ACCURACY

For high accuracy, the module incorporates SigmaDelta data conversion on a per-channel basis, which can provide new analog input readings every 25 ms, and a configurable integration period to remove any process noise and power line frequencies. Each time period, the FBM converts each analog input to a digital value, averages these values over the time period and provides the averaged value to the controller.

STANDARD DESIGN

FBM202 has a rugged extruded aluminum exterior for physical protection of the circuits. Enclosures specially designed for mounting the FBMs provide various levels of environmental protection, up to harsh environments, per ISA Standard S71.04.

VISUAL INDICATORS

Red and green light-emitting diodes (LEDs) incorporated into the front of the module provide visual status indications of the FBM operational status.

EASY REMOVAL/REPLACEMENT

The module can be removed/replaced without removing field device termination cabling, power, or communications cabling.

FIELDBUS COMMUNICATION

A Fieldbus Communications Module or a Control Processor interfaces to the redundant 2 Mbps module Fieldbus used by the FBMs. The FBM accepts communication from either path (A or B) of the 2 Mbps Fieldbus — should one path fail or be switched at the system level, the module continues communication over the active path.

MODULAR BASEPLATE MOUNTING

The module mounts on a DIN rail mounted baseplate, which accommodates up to four or eight Fieldbus Modules. The Modular baseplate is either DIN rail mounted or rack mounted, and includes signal connectors for redundant Fieldbus, redundant independent dc power, and termination cables.

TERMINATION ASSEMBLIES AND CABLES

Field I/O signals connect to the FBM subsystem via DIN rail mounted or baseplate mounted termination assemblies (TAs). Both these types of TAs are electrically passive. The TAs for the FBM202 are available in the following forms:

 Compression screw type (DIN rail mounted) using Polyamide (PA) material 

 Compression screw type (baseplate mounted) using Polycarbonate/Acrylonitrile Butadiene Styrene (PC/ABS) 

 Ring lug type (DIN rail mounted) using Polyamide (PA) materia

Each DIN rail mounted TA and its associated termination cable provides a feedthrough connection between eight 2-wire thermocouple/mV analog input signals and an FBM202 Thermocouple/mV Input Module. Each baseplate mounted TA provides a feedthrough connection between sixteen 2-wire thermocouple/mV analog input signals and two FBM202 Thermocouple/mV Input Modules.

Reference junction temperature compensation is provided by an isolated resistance temperature detector (RTD) that is integral to the termination assembly. The baseplate mounted TA contains an RTD for each FBM202.

A removable termination cable connects the DIN rail mounted TA to the FBM via a field connector on the baseplate in which the FBM is installed. Termination cables are available in the following materials:

 Polyurethane 

 Low Smoke Zero Halogen (LSZH).