Countermeasures for Influencing Factors of Two‑Color Infrared Thermometers
In electrical equipment faults, thermal defects caused by current effects (conductive circuit faults) feature a heating power proportional to the square of the load current. For heating faults induced by voltage effects (insulation medium faults), the heating power is proportional to the square of the operating voltage. Accordingly, the operating voltage and load current of equipment directly determine the effectiveness of infrared inspection and fault diagnosis.
An increase in leakage current may lead to uneven partial voltage distribution on high‑voltage equipment. If the equipment operates with no load or an extremely low load, fault‑related heating will be insignificant. Even severe hidden faults cannot manifest as characteristic thermal anomalies. Only when the equipment operates at rated voltage with a higher load will heat generation and temperature rise become more prominent, and the thermal abnormal features of fault points be fully revealed.
To obtain reliable infrared detection results, equipment shall be operated at rated voltage and full load as far as possible. Where continuous full‑load operation is unavailable, a targeted operation plan should be formulated. Before and during inspection, the equipment shall run under full load for a certain period (e.g., 4 to 6 hours), allowing faulty components sufficient heating time to reach a stable surface temperature rise.
Since the criteria for infrared fault diagnosis of electrical equipment are generally formulated based on the temperature rise under rated current, the actually measured temperature rise of fault points at the site shall be converted to the equivalent temperature rise under rated current when the actual operating current is lower than the rated value.
