Detcon FP-700 User Manual download pdf (Page 6)

Model FP-700

FP-700 Instruction Manual Rev. 3.0 Page 2 of 40

Figure 2 Wheatstone Bridge

Performance Characteristics

The detector elements maintain good sensitivity to combustible gas concentrations in the Lower Explosive

Limit (LEL) range, as shown in the response curves in Figure 3. However, for gas concentrations significantly

above the LEL range (100% LEL = 5% by volume Methane), the bridge output begins to decrease.

Ambiguous readings above the LEL range dictate that alarm control logic be of the latching type, wherein

alarms are held in the “ON” position until reset by operations personnel.

Figure 3 Response Curves

1.2 Sensor Electronics Design

Intelligent Sensor Module

The Intelligent Transmitter Module (ITM) is a fully encapsulated microprocessor-based package that accepts a

plug-in field replaceable combustible gas sensor. Circuit functions include extensive I/O circuit protection,

sensor pre-amplifier, bridge voltage (temperature) control, on-board power supplies, microprocessor, LED

display, magnetic programming switches, linear 4-20mA DC output, and Modbus™ RS-485 output. Magnetic

program switches located on either side of the LED Display are activated via a hand-held magnetic

programming tool, thus allowing non-intrusive operator interface with the ITM. Calibration can be

accomplished without declassifying the area. Electrical classifications are Class I, Division 1, Groups B C D

and Class I, Zone 1, Group IIB+H

Figure 4 ITM Circuit Functional Block Diagram

Senso r

C ell

Z ero

Adju st

O u tp ut

Inp ut

Vo ltag e

C o m p ensato r /

Ref erenc e Bead

Detec to r /

Ac tive Bead

I/O

Circuit

Protection

485

20mA

Display

Micro-

Processor

Temperature

Control

Pre

Amp

Analog 4-20mA Out

Modbus™ RS-485 Output

Power In

Power Supply

Plug-In

Sensor

Element

1 2 3 4 5 6 7 8 9 10 11 ... 49 50

Comments to this Manuals

No comments

Detcon FP-700 User Manual Page 6

Comments to this Manuals

Related products and manuals for Sensors Detcon FP-700