To live up to the customers' expectations today's standard 19" subracks have to be modular, flexible and economic and above all for the use in numerous application areas. However, occasionally it is more sensible not to use standard subracks, but to construct and individually configure a subrack.

The integration of electronic components into a complex medical appliance is such an example. Here individuality relating to installation areas and location possibilities are particularly relevant.

One platform for all anaesthesia technologies

Dräger Medical AG & Co. is a world leading manufacturer of medical equipment who offer integrated system solutions and services in line with the patient process chain in the CareArea™, Emergency Medicine, OP and Anaesthesia, Intensive Care and Perinatal Medicine as well as Home Care.

The innovative concepts of Dräger Medical are the result of years and years of experience, in particular for the anaesthesia system Zeus®.

Through data connection and the integration with the haemodynamic monitoring and in future also the hospital information system, the user obtains comprehensive information about the status of his patient.

The anaesthesia system integrates all types of anaesthesia, patient monitoring and documentation. Apart from the manually directed gas dosage, for instance automatic administration of oxygen, carrier gas and volatile anaethetics can be carried out.

The Heart of the System, the Control Unit

During the manufacture of a core component part of the system, Dräger Medical worked in cooperation with MSC Freiburg GmbH, a developer and manufacturer of electronic components, systems and equipment. Following on from a previous work for medical equipment, MSC have experience in this field for manufacturing and the required certifications.

A core part of the systems electronics is manufactured in Freiburg, the central control unit of the anesthesia workstation, consisting of several electronics modules. For the housing of the MSC produced modules corresponding subracks were required. Very soon it became clear that a standard 19" subrack, available on the market from different manufacturers, could not be used. Even modular and flexibly assembled products could not do justice to the degree of individuality required. Especially the specified installations areas and fixing possibilities of the end product made unique construction necessary.

MSC relied on the know-how and many years of experience of the packaging specialist Schroff for the development and manufacture of this subrack.

Despite Schroff's very flexible 19" subrack range europacPRO, only a few standard components such as horizontal rails and guide rails could be utilised from this range.

Approx. 80 % of the subrack had to be constructed from customised parts. The subracks mainly consist of a bevelled Aluminium-Zinc sheet, with a special cover.

On the side of the subrack, outside the chassis, is space for interconnections and at the rear a backplane and cabling is integrated.

The frame for the assembly into the end unit consists of one continuous part.

EMC requirements, which are a must for applications in medical technology, could be achieved easily. The front panels used by Schroff are equipped with textile EMC seals, through which the connection between the chassis and the modules is guaranteed. The modular construction was one of the prerequisites determined by Dräger, so that components can be exchanged quickly if need be. In addition to this all electronic components manufactured by MSC are shielded from each other by dividing plastic walls, in order to achieve electrical safety.

For the cooling of the electronic component no special measures were required, outlets and perforations allow heat dissipation via natural convection. What had to be taken into consideration was the exact interaction between EMC shielding and air flow.

The entire mechanical construction was developed in close cooperation between Dräger, MSC and Schroff, so that all experiences and technical manufacturing possibilities could be utilised.

Schroff supplies a 6 U high subrack ready assembled with a separated interior for four 3 U plug-in units and a 6 U plug-in unit. This division is comparable with the standard range of the subrack range europacPRO.

At MSC the backplane is integrated and the module with the electronic components is plugged-in and tested.

As a rule five modules are installed, but further extension possibilities, which are closed off with blank panels, are available.