Transformer Monitoring — Load & Temp

Why It Matters

The Value of Transformer Monitoring

The power transformer is the energy heart of a facility. Overload, harmonic distortion, or cooling system failure can cause permanent damage. Replacement cost is in the hundreds of thousands of TL; delivery time is 8–16 weeks.

Constantly exceeding the critical temperature threshold dramatically shortens lifespan. Every 10% excess temperature halves the service life. Argus continuously reads temperature sensors and alerts before thresholds are crossed.

Transformer Module

Instantaneous load percentage (kVA / nominal kVA)

Primary/secondary voltage and current measurement

Thermometer / PT100 temperature integration

Harmonic distortion (THD) tracking

Night idle-running loss analysis

Temperature-load correlation chart

Critical threshold alarms (email + dashboard)

Load balance — phase symmetry analysis

What Damages a Transformer?

Most transformer faults develop slowly and their first signs are measurable. Argus catches these early signals.

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Overheating

Continuously exceeding the nominal winding and oil temperature limit ages the insulation material. Per the Arrhenius rule, every 6–8°C increase halves the service life. Monitoring the temperature trend detects a cooling fault or overload early.

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Sustained Overload

Exceeding 100% load ratio (kVA / nominal kVA) is not an instant danger; but prolonged operation above 80% creates cumulative thermal stress. Argus reports the load duration distribution, providing data for transformer-upsizing or load-shifting decisions.

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Harmonic Distortion

Variable-frequency drives, UPS units, and LED drivers produce harmonic currents. High THD causes extra heat loss (eddy currents) in the transformer and neutral overloading. THD measurement objectively shows the need for a harmonic filter.

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Phase Imbalance

A current difference between phases overloads a single winding and raises the neutral current. Imbalance exceeding 10% means both loss and wear. Phase symmetry analysis points to the panel where load distribution must be corrected.

Transformer Monitoring Questions

Is an extra sensor needed to read transformer temperature?

Most dry-type transformers ship with a PT100 sensor and a digital thermometer (e.g. a transformer protection relay). Argus reads this relay over Modbus; no extra hardware is required. On older transformers without a sensor, an external PT100 + Modbus temperature transmitter can be added.

What should the load ratio be, and when is an alarm raised?

Below 80% is ideal for continuous operation; above 100% is tolerated briefly but consumes thermal life. In Argus, thresholds are set per project: typically a warning at 85% and an urgent alarm at 100%. The load-temperature correlation also catches an abnormal temperature rise at the same load (a cooling problem).

Which brands of transformer protection relays are supported?

Modbus TCP/RTU register maps of Schneider, ABB, and Siemens energy analyzers and common transformer protection relays are supported. Thanks to the device template system, a new relay model is integrated quickly by defining its register map.

Why is night idle-running loss monitored?

A transformer continuously consumes energy due to iron (core) loss even without load. Higher-than-expected idle consumption during holidays/nights indicates incorrect sizing or a transformer left needlessly energised. In facilities with multiple transformers, consolidating low night load onto a single transformer yields measurable savings.

Detect Transformer Faults Before They Happen