Pepperl+Fuchs KFD2-WAC2-EX1.D Strain Gauge Converter

Technical Overview

Isolated barrier for intrinsic safety, processing strain gauge signals into 0/4-20mA or 0/±10V outputs with two relay contacts, RS-485, and LFD.

Key Features

1-channel isolated barrier
24 V DC supply (Power Rail)
Strain gauge input (full or half bridge)
Output 0 mA ... ± 20 mA or 0 V ... ± 10 V
2 relay contact outputs
Programmable high/low alarm
Configurable by PACTware or keypad
RS-485 interface
Line fault detection (LFD)
Suitable for intrinsic safety applications (hazardous areas)
Can evaluate up to four 350 Ω strain gauges in parallel
Input signal range -100 mV ... +100 mV
Ambient temperature range: -20 to 60 °C
DIN rail mountable

Technical Specification Matrix

Parameter	Value
Signal Type	Analog input
Supply Voltage	20 ... 35 V DC (24 V DC nominal)
Power Consumption	≤ 3 W
Input Type	Strain gauge (full or half bridge)
Field-side Signal Range	-100 mV ... +100 mV
Sensor Excitation Voltage	1 ... 5 V (up to 10 V capable)
Lead Resistance (Field Circuit)	≤ 25 Ω per lead
Output (Current)	0 mA ... ± 20 mA or -20 mA ... +20 mA
Output (Voltage)	0 V ... ± 10 V or -10 V ... +10 V
Output Relays	2 relay contact outputs (change-over contact)
Interface	RS-485
Programming Interface	RS 232 programming jack
Ambient Temperature	-20 ... 60 °C
Degree of Protection	IP20
Physical Weight (kg)	0
Dimensions L x W x H (cm)	11.5 x 4 x 11.8

Industrial Applications

1. Hazardous Area Weighing Systems

This converter is ideally suited for connecting load cells and strain gauges in explosive atmospheres (e.g., chemical plants, oil and gas processing) where intrinsic safety (Ex ia Ga/Da/Ma) is paramount. It galvanically isolates the hazardous area input from the safe area output, ensuring personnel and plant safety while transmitting precise weight data.

Problem Solved

Provides a safe, isolated interface for weight measurement in Zone 0/1/2 or Division 1/2 hazardous locations, preventing ignition from electrical faults while maintaining high measurement accuracy.

Intrinsic SafetyHazardous AreaLoad CellsStrain GaugesGalvanic IsolationWeight Measurement

2. Industrial Tank Level Monitoring

In chemical storage or food processing facilities, strain gauge-based level sensors (load cells under tanks) can be precisely monitored. The KFD2-WAC2-EX1.D converts the mV signals from the strain gauges into standard 0/4-20 mA or 0/±10 V outputs for PLC/DCS integration, with programmable high/low alarms for critical level thresholds. Its IP20 rating requires installation within a suitable enclosure, typical for control cabinet mounting.

Problem Solved

Accurately and reliably converts low-level strain gauge signals from tank level sensors into robust analog signals for control systems, with built-in alarm capabilities for process safety and control.

Tank Level SensingStrain Gauge TransducersAnalog OutputProcess ControlProgrammable Alarms

3. Structural Health Monitoring of Bridges/Buildings

For long-term monitoring of stress and strain in civil structures, this converter can interface with arrays of strain gauges. Its RS-485 capability allows for networked data acquisition from multiple units over long distances, transmitting 20-bit resolution measurements to a central monitoring system, even in environments with temperatures ranging from -20 to 60 °C.

Problem Solved

Enables distributed, high-resolution data acquisition from strain gauges in large structures, facilitating continuous structural health monitoring and predictive maintenance through an RS-485 network.

Structural MonitoringStrain AnalysisRS-485 CommunicationData AcquisitionPredictive Maintenance