Connectors: for space, medicine and test and measurement applications

Paul Boughton

Serge Buechli looks at how connectors are used for high-tech applications in markets such as medicine, test and measurement and broadcast.

Connectors are used in markets such as the medical, test and measurement instruments and broadcast, among many others.

Some of Lemo's standard products are specially adapted for space applications. For example, Lemo's connectors are used on communication systems within the International Space Station.

In this instance, special lightweight connectors were developed. The connector shells are made of special nickel-plated aluminium to meet the weight, strength and Electromagnetic Compatibility requirements.

The plastic range of Lemo connectors are also used in space for astronaut health diagnostic systems. Lemo has been incorporated into dozens of other ISS systems, such as power supply, heater units, various sensors, probes and video camera systems.

For space applications, the characteristics of the connector require special material properties in order to prevent outgassing.

For instance, a geostationary satellite is placed on orbital track at an altitude of 35786km. To reach this altitude the satellite and equipment must go through the launch phase and must withstand reduced low pressure conditions.

Plastics and sealants are the most common source of impurities and contaminants in a high vacuum environment. The evaporation of these components releases light weight molecules that eventually contaminate the surface of the connector and favours the appearance of electrical arcs at lower voltages. This phenomenon is well described by Paschen's law (breakdown voltage as function of pressure and gap distance). The voltage necessary for an arc to develop is reduced as the contaminants create an ionized path between the electrical contacts.

Lemo is now proposing a connector that uses material with low outgassing properties. These materials and the connector design prevent voltage creeping on the surface of the insulator for space flight applications. Lemo's altitude connector will operate correctly during pressure drop and temperature cycle. Before installing such a connector, the user must make sure that the connector is exempt of impurities; the connector can be cleaned with alcohol or with an ultrasound bath. Once cleaned, connectors should not be manipulated with bare hands. Before using other cleaning agents or solvents please make sure that the solution is compatible with the plastic and rubber parts of the connector.

Lemo also offers a range of high voltage connectors with 5kV to 70 kV test voltage used in testing facilities and laboratories (not specifically designed for high vacuum). Most of these connectors have been developed to meet the needs of the CERN (European Organization for Nuclear Research) in Geneva.

Production and technology capacity

Lemo's R&D department is represented by engineers, designers and technicians that make a total of over 30 people working on the design and conception of custom connector solutions. Drawings are made on 2D and 3D design software and transferred to production plants for automatic CNC machining.

Lemo has three very well equipped manufacturing centres in Switzerland where production takes place allowing Lemo to draw on the local wealth of expertise in precision machining and assembly. Production lines are equipped with lathing machines for machining larger pieces, while Lemo uses specific machines for manufacturing small complex parts.

Independence treasured by Lemo is largely guaranteed by the 93 per cent added value to its products, as raw material passes through the various processing stages to become part of connecting systems. By manufacturing virtually all its own parts on in-house designed production equipment, Lemo is able to ensure that quality is scrupulously met in all manufacturing phases. Products are continuously controlled in accordance with the ISO 9001 standards. Lemo's commitment to quality has gained official recognition in the shape of the SQS certificate and EQNet.

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Serge Buechli is Product manager, LEMO S A, Ecublens, Switzerland.