A combination of GlobeCore TOR-series devices is recommended, with TOR-80 used for dielectric strength testing. These instruments provide accurate and repeatable measurements, helping assess oil condition and detect early signs of degradation. When combined with GlobeCore purification systems, they allow a full maintenance cycle: diagnostics, analysis, and corrective treatment. This integrated approach significantly improves reliability and extends equipment lifespan.

An important addition to this approach is that truly effective transformer diagnostics should combine both periodic testing and continuous monitoring. While portable devices such as TOR-80 provide accurate on-site measurements, they still reflect the oil condition only at a specific point in time. In practice, many critical faults (such as moisture ingress or early-stage thermal degradation) develop dynamically and may not be captured during scheduled inspections.
For this reason, integrating an online monitoring system can significantly enhance the overall diagnostic strategy. For example, systems such as TOR-5 continuously track key parameters, including moisture, temperature, and even gas formation, allowing operators to detect abnormal trends in real time and respond before they escalate into failures. This shift from reactive to predictive maintenance ultimately ensures higher reliability and better asset management.
If you would like to better understand how such integrated diagnostic systems work and the advantages they offer in real operating conditions, I recommend reviewing this article: https://globecore.com/oil-processing/advanced-transformer-diagnostics-with-globecores-tor-5-system/.

Exactly — the most reliable transformer oil diagnostic strategy couples continuous online monitoring with targeted periodic testing. An online system that tracks oil moisture, temperature profiles, and early gas generation in real time moves you from reactive to predictive maintenance: it catches evolving moisture ingress, hot spots and incipient thermal faults by trend analysis and can trigger corrective action (filtration, drying or deeper degassing) before insulation or winding damage occurs. Portable testers remain essential because they provide spot-check verification (tan delta, breakdown voltage, detailed dissolved gas or hydrogen checks) and cover transient events or sensor drift that an online node might miss.

For practical deployment, fit critical or high‑risk transformers with an online monitor to capture moisture, oil temperature and hydrogen/gas trends and integrate its alarms with your asset management system so processing equipment can be started automatically or technicians dispatched. Complement that with scheduled spot checks using portable oil moisture, hydrogen/DGA and tan‑delta/BDV testers (frequency based on asset criticality: event-driven plus quarterly or annual baseline campaigns). Tie online alarms and periodic test results into your maintenance workflow, keep sensors and portable instruments calibrated, and use vacuum/thermal degassing or CMM purification systems when trends or tests indicate contamination. If you want, I can suggest a sample monitoring and sampling cadence for low-, medium- and high-risk transformers or help map specific devices and integration options for your fleet.