The aerospace segment has been dealing with questions of high voltage systems for the last decade. Many of these questions revolve around the generation, storage, and use of this power, but what has also been a hindrance for progress is defining how the standards for the wiring system need to be updated to address these high voltage requirements. As should be done when any new technology is being applied to a field, we should first look at other fields which have undergone the implementation of similar technologies. For example, the automotive market has been using high voltage systems for quite some time and the standards committees have produced documents supporting these technologies.
In this article, we review one of these documents on high voltage directed to the automotive market and see how it lines up with the existing aerospace standards.Read more
An area of power transmission that we have not talked about in any Lectromec article thus far is the impact of skin effect. While this is an area that is well documented and understood for signal/data cables, the impacts in the area of power cables have been generally ignored. However, as power systems embrace new power technologies, skin effect starts to creep in to have a noticeable and measurable impact. In this article, we discuss what skin effect is and its impact.Read more
The backshell of a connector is an item that perhaps does not get the attention that it should. Often the discussion of EWIS focuses on the wiring, the connectors, or managing the risk of EWIS failures, but the connector backshell is ignored. The simple connector backshell (that is anything but simple) is designed for support and protection of wires and cables physically and, in the case of signal cables, support and protect electrically too. The following is a brief introduction to backshells, their use, associated standards, and research that has been performed to determine what to look for when performing maintenance.Read more
An area that has been poorly defined until recently has been the potential damage to wire/cable insulation due to wiring installation on aircraft. The latest revision of NEMA 27500 has looked to address this gap in cable assessments. In this article, we review the test requirement, expected performance, and what the results may mean to designers and installers.Read more
PD is not a simple phenomenon to model as there are many environmental factors that have influence. Factors such as heat, humidity, pressure, are some that can change the voltages required to initiate and extinguish PD within a wire/cable’s insulation. This article specifically discusses the influence of altitude on partial discharge events. The consideration of the operational altitude effect on partial discharge is particularly necessary for aerospace applications as aircraft tend to spend a lot of operating time at high altitudes.Read more
Plating materials used on electrical connectors are imperative to the connector maintainability and dependability throughout its service life. In the last article on MIL-STD-1353, we discussed Tin as a plating metal, its restrictions in practical use, and the potential of whisker formation which can lead to destructive arcing or short circuit events. Here, we discuss the use of gold and nickel as plating metals and their effectiveness when used together.Read more
For the last 17 years, Lectromec publications have discussed items related to the aerospace wiring installation standard AS50881. The standard is often referenced in many of our articles, but Lectromec has never really talked about what this standard is, why it should be used, who should use the standard, and what should be considered when the standard is employed.
To remedy this oversight, this article seeks to address the question many come to ask when approaching EWIS: why should I care about AS50881?Read more