HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Tool_maker
User Rank
Platinum
Duplicating Problem
Tool_maker   10/24/2012 12:57:38 PM
NO RATINGS
  Your story demonstrates one of the keys to trouble shooting many problems: Being able to duplicate the failure. So many times there is a problem that appears randomly and until I can find out why, I am never totally satisfied with the fix. Even if it is my own error, just correcting it without knowing the thought process that caused the error to begin with drives me crazy.

notarboca
User Rank
Gold
Re: Surge impedance
notarboca   10/17/2012 9:20:46 PM
NO RATINGS
DanSchwartz, you included a lot of knowledge in your post; I learned a lot.  Thanks for the post!

DanSchwartz
User Rank
Gold
Surge impedance
DanSchwartz   10/12/2012 10:40:41 AM
NO RATINGS
It's called surge impedance Zo, which is defined as √(L/C), where L is the inductance in Henrys, and C is the capacitance, which for a coil is the interwinding stray capacitance.

The back EMF V= ZO(∂I/∂T), and it will have an oscillation frequency 1/(2π√LC). When you open up contacts in an inductive load, ∂I/∂T goes to ∞: You see this as an arc when you unplug an iron; and also when relay & motor starter contacts are switching off an inductive load.

This is also why contactors have serious current deratings when switching off DC: Once the arc is established and current flows through the ionized channel, there is no zero crossing to extinguish the arc, as occurs with AC,

When dealing with AC, you design using the peak (not RMS) value of the load current when calculating, because you don't know where in the AC cycle the contacts will open.

Note: Those of you who are RF jocks will quickly recognize ZO = √(L/C) as the equation for the characteristic impedance of a transmission line: Yes, it's the same thing.

Dan Schwartz,
Editor, The Hearing Blog

John E
User Rank
Silver
Re: Old and new
John E   10/11/2012 11:40:55 AM
NO RATINGS
We had changed the output driver from a completely analog design, to one with a digitally controlled output driver.  The new driver would reset occasionally with the noise or the communications to it would get interrupted.

On the old module the noise would pass through to the output, but the frequencies were well above the system response time.

naperlou
User Rank
Blogger
Old and new
naperlou   10/11/2012 10:34:30 AM
NO RATINGS
John, did you guys compare the old and new analog modules that you had designed?  It would be interesting to know what the design engineer changed between the two.



Partner Zone
Latest Analysis
From faux innovations, to fake artificial intelligence, to an Internet-ready Porta-Potty, here's a look at our favorite hoaxes throughout engineering history.
The implementation of a new diesel fuel standard in the US has considerably improved the environmental performance of diesel vehicles. The Environmental Protection Agency (EPA) says that the new ultra-low sulfur diesel (ULSD) fuel has combined with other improved technologies to reduce diesel's particulate matter (PM) emissions by 99%.
A France-based inventor has built drones modeled after i>Star Wars spacecraft. And he's showing everyone else how to do it, too.
Nearly 30 years after its release, 'New Coke' is still a lesson in product failure for engineers.
Transient-voltage-suppression diode technology eliminates surges and enhances vehicle safety.
More:Blogs|News
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
12/10/2014 8:00 a.m. California / 11:00 a.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.
Mar 30 - Apr3, Getting Hands-On with Cypress’ PSoC
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  67


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.
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