Testing & Assessment

New Means to Assess Corrosion Susceptibility

November 2, 2020 Michael Traskos

Low outgassing materials are critical for space applications. As one might imagine, a small, enclosed space with outgassing materials is not an ideal environment. To that end, space system developers have always sought insulation constructions with low outgassing properties. In past articles, Lectromec has covered the developments of the methods and materials used to reduce outgassing. Here, we examine the latest testing techniques for these materials. Read more

Conductor Resistance ASTM B193

August 13, 2020 Michael Traskos

The measurement of resistance seems to be a trivial task. Hook up a standard handheld multimeter with two probes and attach the probes to either side of the device or component that you want to measure. For the most part, this process works well. More correctly, for devices with resistances between 2 Ohms and 1M Ohm, this is a good technique, however, once the resistance values get really high or really low, the process becomes a little more complicated. While the basic physics remains the same (Voltage = Current * Resistance), getting the setup to correctly measure the component requires attention to detail. Read more

Solder Sleeves and Splicing in Shields

May 15, 2020 Michael Traskos

Shielded cables are necessary. They provide necessary EMI protection to ensure signal fidelity, and in some cables, such as coaxial cables, the shield is integral for signal transmission. Trying to use only non-shielded cables in any modern design would encounter such a significant impact on performance, it may not be possible except for a limited number of applications.

Because of this need for shielded cables, there is a wide range of components and supporting technologies to ensure proper use and reliable transmission of data. One of these technologies is a device to help with shield termination.

Dielectric Constant

April 22, 2020 Chris Wollbrink

There are some properties that are taken for granted with wires and cables until they are needed for precision applications. A conductor’s conductivity is assumed until the impact of a voltage drop or heating must be determined. In the same way, a cable’s dielectric constant is uninteresting until the integrity of high-frequency signals becomes critical.

This last property (dielectric constant), is important not only for cable insulations but also for a wide range of applications.

Light Weight and Normal Weight Wire Constructions

April 10, 2020 Michael Traskos

Saving weight is a large part of any aircraft design. Naturally, the electrical system is not exempt from the goal of shaving off a couple of pounds. This often comes in the form of looking for lighter connectors, lighter clamps, and also lighter wire constructions. Those that have done this have undoubtedly come across two classifications of wire construction: “Normal weight” and “light weight”. Of course, if the EWIS has to go on a diet, then the “light weight” construction looks like a good substitute for the “normal weight”… after all, why would the wire be called “light weight” if not for satisfying weight requirements. Read more

The Impact of a Short Circuit on Conductor Performance

March 17, 2020 Laura Wishart

Over-current and shorting are an ever-present risk to power wires and cables. The hope is that circuit protection can quickly respond to over-current conditions fast enough to prevent any damage to the circuit components. Wire conductors have a temperature rating, limited by the plating, because that is the established temperature for long-term reliability. But what happens when a single wire is exposed to repeat over-current conditions? Does the latest generation of circuit protection sufficiently protect the wiring? Read more

Notch Testing and the Impact of 1000 Cuts

March 4, 2020 Michael Traskos

How much damage can a single wire take? Does the failure of a wire’s insulation require one large trauma (think of dropping a hammer on it), or is it possible for the insulation to fail due to 1,000 small cuts? That has been a question plaguing wire system sustainment for decades. Identifying one large trauma can be easy, but to catalog all the minor traumas is impossible. Read more

Non-Standard Standard Part Performance

November 11, 2019 Michael Traskos

Standardized products made by different manufacturers through different processes will undoubtedly yield variable product performance. The expectation is that each ‘qualified’ product should perform comparatively well, but anecdotal evidence suggests that this is not the case. This paper reviews recent work performed by Lectromec investigating the qualified wire/cable performance variability in both qualification tests as […] Read more

Determining Voltage Drop

October 11, 2019 Michael Traskos

If voltage is applied to a circuit and the attached equipment does not turn on, then there is an issue with either the circuit or the applied voltage (assuming the device is fully functioning). Sometimes glossed over in circuit design, the length and gauge of a wire can impact the voltage to the load; this is known as “voltage drop”. Just as the current carrying capacity of a wire/wire harness is impacted by the system and environment, so too is the voltage drop.

In this article, we go over the idea of voltage drop, guidance on its application in design, and an example of quantifying the voltage drop on a wire/cable.

Impact of Wires Used as Ladders

May 22, 2019 Devon Gonteski

Ideally, an aircraft’s EWIS aging is considered and monitored over time, but something as simple as gripping and pulling a wire or cable can change its electrical performance, specifically conductivity and resistance. Read more