Intermittent Fault

An intermittent fault is a phenomenon common to all branches of engineering and also in computer software. It is defined as a malfunction of a device or system that occurs periodically, either at regular intervals or more commonly at irregular intervals. Outside of these periods, the device or system functions normally. The cause of an intermittent fault is several contributing factors occurring simultaneously. The more complex and sophisticated the system or mechanism involved, the greater becomes the risk of an intermittent fault occurring.

Intermittent faults are notoriously difficult to fix because the individual factors do not create the problem on their own and are therefore impossible to identify as causes without prior experience or identifying them while the malfunction is actually occurring. In addition, the engineer capable of identifying and solving the problem is seldom the usual operator. Because the malfunction is unpredictable in terms of timescale, and both the downtime of the device/system and time available to the engineer are limited by economics, the fault is often simply tolerated unless it becomes progressively more frequent or poses a serious threat. For example, in a machine associated with life-support such as an anesthetic machine, the presence of an intermittent fault carries a risk of death to the patient.

The best way of fixing an intermittent fault is for an engineer to observe the fault and measure the all variable conditions at the time, or for these conditions to be automatically logged and then scrutinised over the period of a malfunction. Once all the causing factors have been identified, action can be taken to ensure that they do not occur simultaneously.

External links

* [http://www.chiark.greenend.org.uk/~sgtatham/bugs.html A discussion of software debugging ]
* [http://www.riserbond.com/Ext/uf/ifd.html a discussion on intermittent faults in cables]