Understanding time current curves: Part 1

Posted by David Paul on January 28, 2014 @ 2:36 pm

The first installment of a three-part series about time current curves (TCCs) provides a quick overview of item identification and how to read TCC plots.

A time current curve (TCC) plots the interrupting time of an overcurrent device based on a given current level. These curves are provided by the manufacturers of electrical overcurrent interrupting devices, such as fuses and circuit breakers. These curves are part of the product acceptance testing required by Underwriters Laboratories (UL) and other rating agencies. The shape of the curves is dictated by both the physical construction of the device as well as the settings selected in the case of adjustable circuit breakers. The time current curves of a device are important for engineers to understand because they graphically show the response of the device to various levels overcurrent. The curves allow the power systems engin... Continue Reading

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Configuring control systems through wireless devices, remote I/O: With great power comes great responsibility

Posted by Bruce Brandt on January 23, 2014 @ 4:18 pm

In the new world of wireless devices and remote I/O we have the power to create control configurations that use I/O and that are not physically connected to the controller running the control loops.

In the new world of wireless devices and remote I/O we have the power to create control configurations that use I/O and that are not physically connected to the controller running the control loops. In the case of at least one distributed control system (DCS), the I/O attached to its gateway can be assigned to different controllers on a per I/O point basis. Within the confines of the configuration application there are pointers to where these live, but in the context of project documentation the world becomes a bit blurry. Wireless I/O is another story all together. Even if the technician trying to troubleshoot the loop knows which wireless gateway the device is talking to, that ... Continue Reading

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Microsoft Windows: The evolution and where MS operating systems stand today

Posted by Art Howell on January 10, 2014 @ 10:22 am

Since the 1980s Microsoft has been a leader in operating systems, but these days the competition with Android and Apple devices has them struggling to keep up.

My recent posts have entertained the subjects of PCs in the workplace and virtual machines and how they fit into the workplace. Following suit, I’d like to touch on some Microsoft (MS) Windows history and what possible role the operating system (OS) might play in the future of computing. I have always liked staying on top of the latest technologies; I purchased the MS Windows 95 upgrade as soon as it was available from MS; Windows 95 was the primary predecessor of modern-day Windows and a major upgrade from version 3.1.1. I bought one of the first marketed PCs that ran the Pentium chip. As a matter o... Continue Reading

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Good vs. poor documentation: Don’t be ‘that guy’

Posted by Jeff Monforton on December 17, 2013 @ 2:20 pm

A well organized and well documented system, complete with commentary within your code, can only help you and your fellow developers and programmers.

Over the years we have all had to modify, repair, debug, and otherwise live with someone else’s code. The platforms vary, but the challenges remain the same—the biggest of which is, “What in #@$! was this guy thinking?!” Looking at that single—sometimes painful and often confusing—question leaves us wondering how it happened in the first place. More often than not, we find ourselves in this perplexing situation because the documentation has become separated from the program. This can happen for various reasons: - The equipment has changed hands several times, misplacing information - Someone saw this as an opportunity to insure continued employment by being the ‘go to’ guy - The dog ate it - It was never ... Continue Reading

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Some perspectives on MES implementations: Part 1

Posted by John Clemons on December 17, 2013 @ 2:19 pm

A lack of understanding or definition of MES within a company can lead to the same mistakes being made on project after project.

I think everyone knows by now that I’m a manufacturing execution systems (MES) guy from way back. I’ve been doing MES since way before they even called it MES. In fact, when I started doing it we didn’t even have a name for it. MES is one of the names for a class of computer-based systems that are focused on the execution side of manufacturing. Another common name for these systems is manufacturing operations management (MOM). I’ve seen more MES implementations than I can count, and I’ve seen so many of them that I’m seeing the same mistakes being repeated. It’s interesting in that the industries might change, the software might change, but the mistakes that are being made are the same. An entire class of mistakes can boil down to ... Continue Reading

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