B&R X20CM0985 Multi‑Measurement Transducer and Synchronization Module

The B&R X20CM0985 is a highly integrated multi‑measurement transducer and synchronization module within the X20 I/O system. It is designed to measure electrical parameters (voltage, current, power, frequency) from three‑phase AC networks and provide seamless synchronization between two independent power sources, such as a generator and the public grid. This module is ideal for power generation, energy monitoring, and grid connection applications. It simultaneously monitors two independent three‑phase mains networks plus two additional voltages, providing a complete solution for power quality analysis, generator control, and cogeneration systems.

Technical Specifications

Functional Description

The X20CM0985 integrates both measurement and synchronization functions in a single module. It continuously acquires voltage and current signals from two independent three‑phase AC networks (e.g., generator busbar and grid busbar). The module calculates RMS values of voltage, current, active/reactive/apparent power, power factor, frequency, and total harmonic distortion (THD). The high‑speed data acquisition (conversion time configurable to 20 ms at 50 Hz or 16 ms at 60 Hz) ensures real‑time monitoring. The built‑in synchronization unit compares the phase angle, frequency, and voltage magnitude between the two networks and can control generator synchronization via the digital outputs. The module also features a low‑pass filter for total power readings, improving stability in noisy environments.

Measurement and Synchronization Capabilities

The module measures power in both 4‑wire (star) and 3‑wire (delta) network configurations. For voltage measurement, the inputs can be configured for either 120 V AC or 480 V AC ranges, automatically scaling the data. The current inputs accept signals from external current transformers (typical 1 A or 5 A). The module provides direct digital values (32‑bit integers) for each measured parameter, which are accessible via the X2X bus to the CPU. The synchronization unit can be used for generator controller applications, ensuring that the generator is synchronized with the grid before closing the breaker, preventing damage to equipment.

Digital and Relay Outputs

The X20CM0985 features five digital outputs (current‑sourcing FETs) rated at 0.5 A at 24 V DC. Each output is protected against short circuits and overtemperature, with diagnostic feedback to the CPU. These outputs can be used to control external contactors, circuit breakers, or alarm relays. The module also includes a single changeover relay output, rated for 1 A at 240 V AC or 30 V DC, suitable for low‑power switching applications, such as signaling a generator ready or a fault condition.

Integration with Automation Studio

The X20CM0985 is configured and programmed using B&R Automation Studio. The module appears as a device in the X2X I/O bus configuration. Standard function blocks are available for reading all measured values, performing synchronization, and controlling the outputs. The module also supports user‑defined scaling, filtering, and limit monitoring, with the ability to generate alarms when thresholds are exceeded. The diagnostic system continuously monitors the internal health of the module and the connected sensors, reporting any wire break or measurement errors.

Typical Applications

The X20CM0985 is used in:

• Generator synchronizer panels (diesel or gas generators)

• Energy management systems (power consumption monitoring in factories and buildings)

• Cogeneration and renewable energy plants (grid connection monitoring)

• Power quality analyzers (monitoring voltage sags, swells, and harmonics)

• Distributed energy resource (DER) control systems

Installation and Wiring Overview

The module mounts on a B&R X20 base plate and connects via the X2X bus. It accepts 24 V DC power from the backplane. Voltage measurement connections are made using screw terminal blocks (included), with dedicated terminals for each phase (L1, L2, L3) and neutral. Current inputs use a separate plug‑in connector. Use shielded twisted‑pair cable for current transformer connections, with the shield grounded at the module end only. The digital outputs are protected against short circuits; however, external fusing (1 A) is recommended for each output. The relay contacts are not internally protected; add an external RC snubber for inductive loads.

Conclusion

The B&R X20CM0985 combines precise three‑phase power measurement and generator synchronization in a single compact module, simplifying the design of power monitoring and grid connection systems while reducing the need for separate measuring instruments.