Maximum Harness Ampacity
The fundamental concept here is harness ampacity: the maximum amount of current transferred down a wire harness without exceeding the temperature rating for any component. Read more
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Ampacity Improvements
When electrical current flows down a conductor, it gets warm due to resistive heating. The more current that flows, the warmer the conductor gets. Depending on the wire gauge, conductor conductivity, and ambient temperature of the wire location, the conductor temperature reaches the maximum certified temperature. This maximum electrical current is where the outward heat […] Read more
Skin Effect
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 moreAn Introduction to AS50881
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 moreConductor Resistance ASTM B193
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
Impact of Secondary Wire Harness Protection on Heating
If you are standing outside on a cold winter day, would you be warmer in a T-shirt or in a jacket? The answer is obvious, but somehow that ‘obvious answer’ is obscured when thinking of aircraft wire harness design. A common question of OEMs and aftermarket modifiers is: how much of an impact (if any) does secondary harness protection have on wire harness heating?
Lectromec took time this last week to put together a representative harness and run tests to generate data on the thermal impact of three secondary wire harness protection schemes. While this data is not representative of every wire harness configuration, it does provide a basis for determining if additional testing (or simulation) are needed for your application.
Read moreSAE Wire and Cable Committee Meeting Update – Fall 2019
The SAE wire and cable committee held their fall 2019 meeting in San Diego this year. As with every committee meeting, a lot of technical areas were discussed, progress was made, and some new ideas/problems are emerged. As we do after all these meetings, we put together a highlight of some of the talking points from the meeting.
Read moreDetermining Voltage Drop
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.
Read moreTop 5 Articles from 2018
At the end of every year, Lectromec rummages through that year’s publications and articles to find the most popular ones. In 2018, this required going through 32 articles (7 were picked up by publications), revisiting two webinars, and 12 podcasts. Here are the top 5 Lectromec publications of 2018. Read more
Have we Reached the End of Aging Aircraft Wiring Systems?
The way some in the aerospace industry maintain their aircraft wiring system can only lead an external observer to reason that aircraft wiring is impervious to damage with a life-span greater than the sun. When considering this thought, the question arose, “It is possible that aircraft wiring reached a point where aging/degradation is a thing of the past?” Read more