Cressall engineers can select expanded mesh with any configuration of element length, cross-section, material thickness, banking arrangement and cooling method to suit the requirements of the application.
Expanded mesh resistors can be made from any suitable resistance material. As standard Nickel chrome and iron-chrome-aluminium alloys are used. The selection is based upon cost, temperature coefficient of resistance and magnetic properties.
Excellent heat dissipation
Expanded mesh elements provide a very large surface area relative to mass, giving excellent heat transfer capabilities and making them ideal for continuous duties.
The active material, insulators and mountings on expanded mesh resistor elements are designed to maximise the use of convecting air for ventilation. An unrestricted path through the active material avoids ‘hot spots’ and local overheating.
Expanded mesh resistor elements cool from 600°C to almost ambient temperature in approximately one-eighth of the time taken by an average grid. This means that expanded mesh resistors are also suitable for continual ‘on/off ’ cycles, making full use of the ‘off ’ periods for rapid cooling.
Expanded mesh elements and their mountings are lighter in weight per kilowatt than any other known type.
In tests up to 1MHz, expanded mesh resistor elements have been demonstrated as non-inductive for all normal practical purposes.
Expanded mesh elements are robust and capable of withstanding vibration, yet sufficiently flexible for shock absorption.
Elements have the advantage of fixed mountings: movement due to thermal expansion is absorbed within the mesh structure itself.
Although the heated part of the element and the metal supporting it are formed from a single sheet, heat is kept out of the mountings, terminations and supporting insulators to a much greater extent than with other designs.
Primary insulation consists of micanite tubes and mica washers. Secondary insulation consisting of ceramic insulators may be added to permit operation at any required voltage level.