A Method for Determining the Impact of Ambient Temperature on an Electrical Cable during a Fire

Abstract

Evaluating environmental conditions that trigger fire-fighting equipment is one of the primary design tasks that have to be taken into account when engineering electrical systems supplying such devices. All of the solutions are aimed at, among others, preserving environmental parameters in a building being on fire for an assumed time and at a level enabling safe evacuation. These parameters include temperature, thermal radiation, visibility range, oxygen concentration, and environmental toxicity. This article presents a new mathematical model for heat exchange between the environment and an electric cable under thermal conditions exceeding permissible values for commonly used non-flammable installation cables. The method of analogy between thermal and electrical systems was adopted for modelling heat flow. Determining how the thermal conductivity of the cable and the thermal capacity of a conductor-insulation system can be applied to calculate the wire temperature depending on the heating time t and distance x from the heat source is discussed. Thermal conductivity and capacity were determined based on experimental tests for halogen-free flame-retardant (HFFR) cables with wire cross-sections of 2.5, 4.0, and 6.0 mm2. The conducted experimental tests enable verifying the results calculated by the mathematical model.

Determining the thermal-physical characteristics of a coke foam layer in the fire protection of cable articles with foaming coating

“…Assessment of environmental conditions under which fire-fighting equipment is triggered is one of the main design tasks that must be taken into account when developing electrical systems that supply such devices [11]. All solutions are aimed, among other things, at preserving the environmental parameters in the building that burns for the estimated time and at a level that ensures safe evacuation.…”

“…Given that the function erfc X is unambiguous [18] we equate equations (11) and (12) to derive the dependence:…”

Special Issue: “The Design and Optimization of Fire Protection Processes”

“…In fire testing, fire characteristics are parameters that can help to evaluate the behaviour of the materials in a fire [13]. The parameters listed in fire tests are specific to each phase of a fire [14].…”

Ampacity Decrease in a Three-phase Power Cable Fed by an Uncontrolled Rectifier and Finding a Lower Limit for the Power Cable Loss

“…The effects of harmonics on underground power cables are examined by considering a real system and using experimental data and shown to result in an excessive temperature rise due to the power losses in the cable [7]. Aging processes such as water treeing, electrical treeing, and dielectric breakdown can be observed in polymeric insulators of cables [8] and the high-temperature operation of cables also contributes to their early aging [9][10][11]. Cable failures and degradations that may occur directly or indirectly in the cable due to harmonics should be prevented [11,12].…”