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.
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.
Government regulations, coupled with growing consumer sensitivity about data and identity theft, require that data storage organizations demonstrate proper protection and due diligence in protecting sensitive information stored inside datacenter enclosures.
When a crane doesn't have a monitoring system, crane owners schedule service every six months and simply scrap the parts they replace, even if a part has had little use and doesn't need replacing. This can cost thousands.
A quick look into the merger of two powerhouse 3D printing OEMs and the new leader in rapid prototyping solutions, Stratasys. The industrial revolution is now led by 3D printing and engineers are given the opportunity to fully maximize their design capabilities, reduce their time-to-market and functionally test prototypes cheaper, faster and easier. Bruce Bradshaw, Director of Marketing in North America, will explore the large product offering and variety of materials that will help CAD designers articulate their product design with actual, physical prototypes. This broadcast will dive deep into technical information including application specific stories from real world customers and their experiences with 3D printing. 3D Printing is