Precision DC Signal Conversion for Reliable Monitoring and Control

The Challenge of DC Signal Diversity

Direct-current measurement and control are essential to every power and industrial automation system, yet DC signals rarely come in a single form. In substations, 110/220 VDC control power must be monitored accurately to ensure dependable tripping and closing operations. In industrial environments, PLCs and DCSs typically accept only standardized analog inputs such as 4–20 mA or 0–5 V, while field devices often output unscaled or non-isolated DC values.

The engineering problem is simple but critical: how to measure, isolate, and standardize diverse DC quantities so that they can be safely and consistently processed by protection, automation, or energy-management systems.

The ODES SET500 Series DC transducer from ODES provides an integrated solution—offering three-way isolation, precision scaling, and noise immunity within a compact, rail-mounted package.

Substation Applications — From “Unseen” to “Quantified”

In secondary DC systems, small voltage deviations can cause protection malfunctions, and uncontrolled ripple currents can distort measurements. Continuous, linear, and interference-resistant monitoring is therefore a prerequisite for reliable system operation.

By using the SET500 transducer, substation engineers can:

• Isolate the power, input, and output circuits to eliminate circulating currents and potential-ground interference.

• Convert DC bus voltage or battery charging/discharging current into 4–20 mA or 0–5 V standardized signals for RTUs, SCADA, or measurement-control units.

• Configure range scaling (e.g., 0–300 V for a 220 VDC system) to balance redundancy and resolution.

• Set alarm thresholds to log over-/undervoltage events for predictive maintenance.

Field Example: In a 220 kV substation expansion project in eastern China, the DC bus voltage and battery current were both standardized using the SET500 before being sent to the measurement-control system. After commissioning, false and missed alarms caused by voltage fluctuations dropped significantly, and periodic inspection time was shortened through accurate trend correlation.

Industrial Automation — Converting “Wild” DC Signals to Standard Process Variables

Brownfield retrofits often involve legacy sensors producing mV, non-isolated DC, or other nonstandard outputs. Meanwhile, control systems demand uniform, isolated analog inputs.

The SET500 bridges that gap:

• Accepts nonstandard or unisolated DC inputs and outputs fully isolated, scaled 4–20 mA or 0–5 V signals.

• Offers high immunity to electromagnetic interference, fast response, and precise linearity for process feedback loops.

• Features a narrow DIN-rail enclosure suitable for dense cabinet layouts and rapid replacements.

Field Example: At a paper mill retrofit project in Dongguan, multiple process DC signals were standardized to 4–20 mA before feeding the DCS. With tight shutdown windows and complex wiring, the modular design of the SET500 simplified installation, reduced downtime, and allowed easy channel replacement during later maintenance.

Renewable and Energy Storage Systems — Making the DC World Measurable

Solar and storage installations present additional challenges: fluctuating DC voltages, long cable runs, and frequent surge or lightning events.

By deploying the SET500 at combiner boxes, DC bus sections, and battery clusters, operators can:

• Achieve three-way isolation and standardized signal output for EMS or SCADA integration.

• Apply configurable thresholds to generate actionable overcurrent or voltage-limit alarms.

• Maintain continuous, traceable data for predictive energy management.

Field Example: A 100 MW photovoltaic-plus-storage hybrid site in northwest China maintained uninterrupted DC-side data acquisition throughout the lightning season using SET500 transducers. The stable DC profiles enabled the dispatch center to fine-tune inverter control strategies, improving predictability and output consistency.

Engineering Advantages

• Three-way isolation between power, input, and output circuits—suppressing surge, electrostatic, and fast-transient interference.

• High accuracy and rapid response, supporting both process control and continuous DC monitoring.

• Universal analog outputs (4–20 mA, 0–5 V) compatible with multi-brand PLCs, DCS, and protection I/O modules.

• Wide auxiliary power range, simplifying cabinet retrofits.

• Compact DIN-rail housing, enabling high-density installation and easy maintenance.

The SET500 Series provides a field-proven approach to DC signal conversion and isolation, transforming complex, multi-source DC inputs into reliable, standardized measurements. Whether in a substation secondary system or an industrial control cabinet, the SET500 ensures that your monitoring and control systems measure accurately, transmit consistently, and operate with confidence.

Turn DC diversity into standardized data you can trust.

• Request technical specifications and wiring examples for the SET500 Series.

• Consult our engineering team for guidance on scaling, isolation, and interference control.

• Simplify your measurement chain and enhance your system’s reliability with precision-engineered DC transducers.

Contact: 📩 tonyzhang@odes-electric.com

Or visit: 🌐 https://www.odes-electric.com/

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