This application story examines the integration of diverse voltage monitoring points into a standard current loop architecture within an industrial control environment. By utilizing high-accuracy signal conditioning, a system integrator successfully bridged the gap between high-voltage DC bus monitoring and standard PLC input requirements.
- Precise 10:1 voltage attenuation for high-voltage DC monitoring.
- Robust 3-port isolation to protect control hardware from transients.
- High input impedance to prevent signal distortion on sensitive voltage sources.
A system integrator was tasked with replacing legacy signal conversion hardware in an industrial automation environment where diverse voltage signals required normalization for PLC and SCADA integration. The primary challenge involved bridging two distinct signal levels: standard 0-10V DC outputs and higher-voltage 0-100V DC bus monitoring points. These signals needed to be converted into industry-standard 4-20mA current loops to maintain signal integrity over long cable runs and ensure compatibility with the existing control infrastructure.
The technical solution centered on the ISOCON series, a universal signal conditioning platform known for its high-stability 3-port isolation. This isolation is critical in industrial environments where ground loops and high-voltage transients can propagate through the system, potentially damaging sensitive PLC analog input cards. For the 0-10V inputs, the ISOCON series was configured to provide an isolated 4-20mA source output. A key technical advantage of this series is its 1MΩ input impedance on voltage ranges, which ensures that the converter draws a negligible amount of current from the source. This high impedance prevents the loading down effect that can otherwise distort readings from high-impedance sensors or process controllers, maintaining high end-to-end measurement accuracy.
To address the 0-100V monitoring requirement, a specialized attenuation approach was implemented using the DIVIDER series. Since standard high-accuracy converters typically max out at a 10V or 20mA input, the DIVIDER module was utilized to provide a precision 10:1 reduction, safely scaling the 0-100V signal down to a 0-10V range. This scaled output was then processed by a second ISOCON series unit. This modular approach preserves accuracy through a high-precision resistor network while providing a safe, galvanic barrier between the high-voltage DC bus and the control room electronics.
ISOCON-6 24V ac/dc Powered 0-10V to 4-20mA Signal Converter
- SKU ID: s1-isocon-0033
- Part No: II-ISOCON-6-G000-A-000
- Input Type: 0-10V
- Output Type: 4-20mA
- Supply: 12-36 Vdc or 12-32Vac
- Isolation: Full 3-Port
- Installation: DIN Rail TS35
- Electrical Connections: Screw clamp with pressure plate
DIVIDER 10:1 Voltage Divider Module
- Part No: II-DIVIDER
- Function: 10:1 Voltage Division
- Input Voltage Range: 0-100V AC/DC
- Output Voltage Range: 0-10V AC/DC
- Mounting: DIN Rail TS35