Precision resistors serve on space lab

It is by no means easy to fulfil the stringent requirements set by aerospace and space organisations.

Components must function reliably even when subjected to extreme influences.

For example, the SMx series resistors for use in space can endure the vibrations which occur when the shuttle lifts off, remain undamaged in conditions of ultra high vacuum and at high levels of radiation and still perform consistently at a temperature of -50C.

To ensure this degree of reliability in such extreme surroundings a large number of tests is performed on individual components taken from normal production lots.

The rigorous testing includes ageing tests, detailed visual inspections and vibration tests.

Most of the resistors deployed in space are manufactured using ISA-Plan technology.

This process ensures a high continuous load capacity (3W) as well as a high pulse power rating.

Also, the temperature increase is low, leading to a correspondingly low resistance drift.

In comparison with copper the electromagnetic force (EMF) of the resistor material manganin is extremely small (less than 1uV/K) and it has a very good long-term stability rating (better than 0.5% at full load).

Isabellenhutte's resistors have already been used in satellites for 12 years.

Its adoption into the space technology authorities' official supplier list for certified components, the European preferred parts list (EPPL) has been announced and is expected shortly.