HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Blogs
Guest Blogs

Design Decisions: Choosing the Right Resistor for Energy Metering

Page 1 / 3 Next >
View Comments: Newest First|Oldest First|Threaded View
tekochip
User Rank
Platinum
Excellent Article
tekochip   8/30/2012 1:47:21 PM
NO RATINGS
Excellent article, very thorough and detailed.  Few people realize how difficult it can be to specify a simple resistor.  It's also quite common to use two resistors in series to satisfy redundant failure analysis.


tedtw
User Rank
Iron
Electric meter current measurement
tedtw   8/30/2012 1:12:51 PM
NO RATINGS
Resistor consideration is related to instantaneous or repeated peak MOV power dissipation, too. Few engineers realize that a lightning stroke does not consist of just one pulse, but five or more together. I proved this years ago with a camcorder, and viewing a lightning strike frame by frame I saw separate bolts of lightning in every other video frame.Our eyes perceive a lightning strike as flickering, but in reality each strike is a series of discharges until the cloud voltage drops low enough to stop altogether.

Consider each meter is also sealed environment with a glass cover, much like a greenhouse but without ventilation. Now consider a typical meter sitting on a outside, south-facing wall on a home in the deep south. Internal temperatures can easily rise up near the upper operating limits for most electronic components.

Both MOV and resistor power ratings must be greatly de-rated to insure long term reliablility of both. De-rating is also required for other electronic components. Proper testing of components requires both good equipment and use of an environmental chamber during testing. This type of testing reveals flaws and design issues with components not previously apparent or even considered as a problem.

With record-breaking temperatures around the country, it's hard to find a more punishing environment for electronic components. Perhaps a oil well probe lowered down to the botton of an oil to make temperature and resistance measurements might be a worse environment, but that's just a temporary high temperature environment, while a electric meter is on-going day after day A wall ona building is even worse than the passenger compartment in most vehicles. At least in the case of vehicles, electronics can be located under car seats or behind the dashboard, away from direct sun exposure.

Partner Zone
More Blogs from Guest Blogs
The Internet of Things (IoT) is frequently defined by consumer or healthcare applications. It’s important to remember, however, that IoT offers at least as much potential to industry. One of the most promising subsets of industrial IoT is embedded vision -- or machinery that can see, interpret data, and act accordingly.
Going back to older application notes or archived CEC courses remind us of some of the most useful tricks and techniques we can use to reduce the power dissipation in an MCU-based design.
The Internet of Things is bringing smarter production processes to the factory floor and simultaneously driving data volume and diversity up -- quickly.
New flash welding innovation uses hydraulic motion control, and enables patented welding process for as much as 50% less cost.
Transient-voltage-suppression diode technology eliminates surges and enhances vehicle safety.
Design News Webinar Series
3/31/2015 11:00 a.m. California / 2:00 p.m. New York
2/25/2015 11:00 a.m. California / 2:00 p.m. New York
12/11/2014 8:00 a.m. California / 11:00 a.m. New York
5/7/2015 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Apr 20 - 24, Taking the Internet of Things to the Cloud
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6 |  7


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Last Archived Class
Sponsored by Proto Labs
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2015 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service