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Results for: high voltage

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

IEEE 1584-Arc Standard

September 16, 2020 Michael Traskos

Key Takeaways IEEE 1584 provides a basis and a model for arc flash protection and necessary safe separation distance. The standard targeted the necessary calculations for power distribution. While there is some overlap with the aerospace industry wiring system requirements, the model’s range inhibits its use for aircraft. Research down an unfamiliar path often includes […] 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

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

Checking a Coaxial Cable for Damage with a Multimeter – Part II

September 11, 2019 Michael Traskos

In the last article, Lectromec introduced a damaged coaxial cable and tried three techniques to distinguish it from an undamaged cable. The standard multimeter tests (capacitance, inductance, and resistance measurements) found no appreciable difference.

The idea of this evaluation was to demonstrate that the classic multimeter, while a great tool, is not suitable for detecting damage to coaxial cables.

But we cannot run an article and leave it without a solution. In this article, we continue the testing of a damaged coax cable to see what technology, if any, can identify and perhaps locate the damaged section of cable.

Checking a Coaxial Cable for Damage with a Multimeter

August 23, 2019 Michael Traskos

The electronic multimeter is a great tool; invented in the 1920s, the multimeter has been used by millions of technicians and engineers seeking to measure circuits and troubleshoot electrical issues. So common are these tools now that it is almost impossible to consider a toolbox complete without one.

While these are great tools and can be employed in a million situations, they are not the magic tool that can diagnose every circuit. If only one thing is remembered from this article: multimeters are not the tool to use for coaxial cables

EWIS Physical Hazard Assessment

August 14, 2019 Michael Traskos

Aircraft system safety assessments are not a new concept. These safety assessments have a defined process for evaluating an aircraft which involve identifying its failure modes, top-level events, and eventual means to achieve an unsafe condition. Documents such as the SAE ARP4761 provide guidelines and methods for conducting the safety assessment process on civil airborne systems and equipment.

To follow the typical development cycle, the aircraft failure hazard assessment (FHA) is followed by the system failure hazard assessment and performed in parallel with the preliminary system safety assessments (PSSAs). This then evolves into the system safety assessments (SSA) and common cause analyses (CCAs). For those with a systems reliability background, this should all be second nature. For the rest of the community, these are often terms that we come across because of our work in this field.