Keeping An Eye On Transformer Health

On-line dielectric condition monitoring of bushing and transformer insulation is essential for managing transformer health. MONTRANO continuously monitors the condition of insulation in bushings and transformers...

Dielectric flashover of insulation in bushings and transformers is one of the most frequent causes of failure in power transformers. Aging insulation progressively degrades to the point that it can no longer withstand electrical stress.

This can cause bushings to explode, transformer destruction and long outages for repair.

On-line dielectric condition monitoring of bushing and transformer insulation is therefore essential for managing transformer health.

These online assessments ensure safe, reliable operation during the intended service life of transformers. The MONTRANO on-line monitoring system from OMICRON continuously assesses the dielectric health of bushings and transformers under load. The system records changes in capacitance (C), dissipation/power factor (DF/PF), partial discharge (PD) and transient over-voltages. These are primary indicators of insulation breakdown, which can lead to dielectric failure in bushings and transformers.

Advanced warning of pending failures

Detailed trend charts show you the dielectric state of insulation over time. Early warnings and alarms indicate the severity of negative trends.

This enables you to assess the risk of failure and plan corrective action early to extent transformer service life.

Reliable online results

The system is designed to minimise the misleading impact that changes in grid unbalance (phase shifts) can have on C and DF/PF measurements. It achieves this by using the individual phases of a nearby voltage transformer as an absolute measurement reference. The resulting accuracy enables reliable comparison with recommended supplier reference values to determine bushing insulation condition.

Additionally, the monitoring system employs advanced noise suppression using UHF signals and a unique gating technique for reliable PD source recognition. This enables the system to effectively separate external noise, like corona, from harmful PD.

Web-based data access

A convenient web interface enables you to view data at any time to determine the actual dielectric condition of insulation in bushings and inside the transformer. The interface also allows you to schedule monitoring, set alarm and warning thresholds and check system status.

MONTRANO provides trend data to assess the dielectric health of bushings and transformers…

Expert monitoring support

A dedicated team of HV engineers at OMICRON provides you with expert service and support, such as onsite consulations to evaluate monitoring requirements; system installation, setup and training; as well as assistance with data evaluation and assessment reports.

Factbox – MONTRANO

  • Continuous condition assessment of bushing & transformer insulation
    • Absolute C, DF/PF monitoring for comparison with acknowledged standards
    • Advanced noise suppression for reliable PD source detection
    • HV transient recording at bushings for effective impact correlation
    • Detailed trend data for modern transformer health management.

MONTRANO provides detailed trend charts that show the dielectric state of insulation over time. Early warnings and alarms indicate the severity of negative trends…


The MONTRANO on-line monitoring system is installed at various power utilities around the world. Customer feedback has been positive about this innovative monitoring system for bushings and power transformers.

“The system was able to confirm the existence of Partial Discharge (PD) in one of our transformers. This confirmed earlier DGA results. Many other systems and techniques had been tried previously, but MONTRANO was the only system to successfully prove that the PD was real. The detailed phase resolved analysis of the results carried out by OMICRON has also indicated specific locations which could be the source of the PD.”
– Mr. Colin Feely
Plant Maintenance Engineer
Powercor Australia Ltd.

“Before we started to use MONTRANO, it was not possible for to us to monitor the condition of transformers continuously.
Now with the monitoring system in place, the results that indicate possible defects can be correlated quicker.
The ability to see transient over-voltages at transformer bushings with MONTRANO also offers us new possibilities to assess transformer condition.”
– Erwin Vögel
Voralberg Energienetze GmbH


OMICRON is an international company serving the electrical power industry with innovative testing and diagnostic solutions. The application of OMICRON products allows users to assess the condition of the primary and secondary equipment on their systems with complete confidence. Services offered in the area of consulting, commissioning, testing, diagnosis and training make the product range complete.

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