Equipement design with composite case

The composite housing design saves weight. In aeronautics, this gain is achieved by using less surface area for filtering. With regard to the ever-increasing constraints associated with lightning strikes, the switch to floating electronics eliminates the need for transil diode-type protection to drain the strike current. The constraint becomes an insulation constraint with respect to the voltage with the greatest amplitude.

In telecommunications, insulation is governed by electrical safety standards which, depending on the type of network, impose voltage withstand levels of up to several kilovolts between the part receiving the communication cable and the digital electronics, which are grounded. Composite provides insulation and contributes to the design.

In the world of balneotherapy, the electronics used to manage water pumps for bathtubs are subject to isolations of up to 8 kV between the primary circuit and the electronic control functions. Watertightness requires composite enclosures.

In other environments, such as the electronics installed in a racing car, isolation is more functional: it prevents any pollution caused by currents flowing back to the chassis, and here too, weight is an enemy.

In the field of qualitative measurement and water treatment, equipment is often developed with composite structures that avoid the risk of metal corrosion.

This article explains the problem of electronic systems without metal housings. In fact, the usual best practice of referencing electronics to the chassis becomes impossible. The quality of input/output decoupling is degraded by air coupling. This is followed by a discussion of the devices to be used, based on the rules of the art established by experience.