Calorimetric fire experiments on electronic cabinets

摘要

Six full-scale fire experiments on two types of electronic cabinets as well as four reduced scale experiments have been carried out. In the experiments one cabinet, the fire cabinet was equipped either with relays, connectors, wiring, cables and circuit boards or cables, circuit boards, circuit board rails and connectors and wiring behind the connectors. A mock-up cabinet made of thin steel sheets was attached to the fire cabinet in order to study the response of an adjoining cabinet to the fire. Another cabinet was placed at a distance of 1 m opposite the fire cabinet to represent a neighbouring row of cabinets. In addition, reduced scale fire experiments on cabinets with well-defined contents and ventilation conditions were carried out. The fire cabinet was ignited with a small propane burner either at the bottom of the cabinet beneath a vertical cable bundle or beneath a wiring bundle. Rate of heat release (RHR) by means of oxygen consumption calorimetry, mass loss, CO_2, CO and smoke production rate and gas and wall temperatures in the fire cabinets were measured as a function of time. The key role of the ventilation conditions in the cabinet when determining the RHR was clearly shown. Ignition power and energy sufficient for sustained burning leading to flashover in the cabinet was determined. The ignition power and energy levels seem to be fairly near the limit ignitiono ignition of the cabinet. The fire growth rates after ignition was estimated to be slow.