Overview

Elseta eRTU can record current and voltage waveforms in COMTRADE format. This gives DSOs detailed information about faults and other disturbances in medium-voltage networks.

Unlike a standard SCADA alarm, which only reports that an event occurred, a COMTRADE record shows how electrical values changed before, during, and after the event. Engineers can use this data to investigate faults, check protection operation, and better understand feeder behaviour.

The Challenge

Fault indications and event logs provide useful operational information, but they do not always explain what actually happened in the network.

Without waveform data, it can be difficult to determine:

What type of fault occurred
Whether the event was transient or permanent
How currents and voltages changed during the fault
Whether protection and switching equipment operated correctly
Whether similar disturbances are recurring at the same location

This can lead to longer investigations, unnecessary site visits, and decisions based on incomplete information.

The Elseta Solution

The eRTU records measured currents and voltages when a configured disturbance condition is detected. The recording captures the event and stores it in the standard COMTRADE format.

The resulting file can be opened using common COMTRADE analysis software. Engineers can inspect individual phases, compare voltage and current waveforms, view event timing, and correlate the recording with SCADA alarms, switch positions, fault indications, and Sequence of Events logs.

Because disturbance recording is integrated into the eRTU, DSOs can collect this information directly from secondary substations, RMUs, and MV feeders without installing a separate disturbance recorder.

Additionally, the eRTU’s FPI features on the BCM units can provide bidirectional fault detection with automatic fault-triggered isolation and both transient and permanent fault recognition. You can find more details about the fault detection functionalities here: Elseta Wiki.

Typical Applications

COMTRADE records can support:

Phase-to-phase and earth-fault analysis
Verification of protection and automation operation
Investigation of voltage dips and current peaks
Analysis of switching events and transformer inrush current
Comparison of recurring disturbances
Fault investigation in networks with distributed generation
Remote technical assessment before dispatching field crews

Benefits for DSOs

More detail than a SCADA alarm
Engineers can see the actual current and voltage waveforms associated with an event.

Faster fault investigation
Recorded data helps identify the likely fault type and assess the affected feeder before a site visit.

Protection verification
COMTRADE records can be compared with relay, recloser, and switch operation to confirm whether the protection sequence worked as intended.

Standard file format
Records can be analysed using commonly available COMTRADE tools without being tied to proprietary software.

No separate recorder required
Measurement, remote control, event logging, fault indication, and disturbance recording are combined in one modular RTU platform.

Conclusion

COMTRADE disturbance recording adds detailed post-event analysis to the eRTU’s monitoring and control functions. With recording at MV grid locations, DSOs can investigate disturbances more accurately, verify protection operation, and make better-informed maintenance and network operation decisions.

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