What is ΔT in thermography?

ΔT (delta T) is the temperature difference between the measured component and a reference point (typically a similar component under the same load, or ambient temperature). It is the primary severity indicator in thermographic inspections.

What severity levels are used?

Common severity classification uses four levels: Minor (monitor), Intermediate (plan repair), Serious (repair soon), and Critical (immediate action). The ΔT thresholds vary by component type and industry standards.

What ΔT thresholds apply to electrical panels?

For electrical connections (ΔT over ambient): 1-10°C = Minor, 11-20°C = Intermediate, 21-40°C = Serious, >40°C = Critical. These thresholds are based on NETA MTS standards and are widely used in electrical thermography.

How does load affect thermography readings?

Temperature rise is approximately proportional to the square of the current (I²R heating). When equipment is not at full load, findings may be worse at full load. Always record the load percentage during inspection and extrapolate to full load conditions.

What are the main standards for thermography?

Key standards include ISO 18434 (condition monitoring by thermography), NETA MTS (electrical maintenance testing), ASTM E1934 (IR building surveys), and IEC 62446 (PV systems). ISO 18434 provides the overall framework for machine condition monitoring using IR.

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Límites de temperatura de termografía

Clasifique los hallazgos de inspección infrarroja según la norma ISO 18434. Ingrese el tipo de componente y el ΔT medido por encima de la referencia para obtener la clasificación de severidad y la acción recomendada.

ISO 18434NETA MTSInspección IR

Clasificación

Severidad

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ΔT medido

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Prioridad

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Acción recomendada

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Umbrales de temperatura para este componente

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Indicador de temperatura

Electrical Components (NETA MTS, ΔT over ambient)

ΔT (°C)	Severidad	Prioridad	Acción
1–10	Menor	4	Monitorear, reparar a conveniencia
11–20	Intermedia	3	Planificar reparación en la próxima parada programada
21–40	Grave	2	Reparar lo antes posible
>40	Crítico	1	Acción inmediata — riesgo de falla/incendio

Componentes mecánicos

Componente	Menor	Intermedia	Grave	Crítico
Carcasa del motor	<10°C	10–25°C	25–40°C	>40°C
Soporte del rodamiento	<10°C	10–20°C	20–35°C	>35°C
Acoplamiento	<5°C	5–15°C	15–25°C	>25°C
Trampa de vapor	<20°C	20–40°C	40–60°C	>60°C
Aislamiento	<5°C	5–15°C	15–30°C	>30°C