Stability factor is the difference between the percentage power factor at 80 volts per mil and at 40 volts per mil, measured on wire immersed in water at 75 degrees C.
Stability factor is a measure of how stable an insulation's dielectric behavior is under electrical stress. It is defined as the difference between the percentage power factor measured at a higher voltage stress, such as 80 volts per mil, and at a lower stress, such as 40 volts per mil, with the wire immersed in water at 75 degrees C for a specified period. A small stability factor indicates that the insulation's dielectric losses change little with voltage, which reflects a stable, high-quality dielectric.
Because changes in power factor with voltage can indicate degradation or absorption of moisture in the insulation, the stability factor is used to assess insulation quality, particularly in cable for demanding applications. A stable insulation maintains consistent electrical behavior across voltage stresses.
In commercial and industrial cable, the stability factor reflects the quality and consistency of the dielectric. Recognizing the measure helps in understanding how insulation performance is evaluated.
Because changes in power factor with voltage can indicate degradation or moisture absorption in the insulation, the stability factor is used to assess insulation quality, particularly in cable for demanding applications, with a stable insulation maintaining consistent behavior across voltage stresses.
At Windy City Wire, an understanding of insulation quality measures, including the stability factor, reflects a focus on dependable dielectric performance in low-voltage cable. Recognizing how dielectric stability is assessed helps illustrate the considerations behind quality insulation.