There is a reason that old fuse holders used the same screw thread as lightbulbs.
When a fuse blew, you put a high wattage bulb in and then tried plugging in/out until you discovered the appliance or cord that caused the bulb to go from "off" to "full on".
With today's breakers it is not so easy to go through a set of fuses and blow them all, then to stop and consider that maybe the fuse was not the problem.
and listen for the sound. That would identify a short to ground (or shielding if shielded cable, which would then be terminated to ground at the source point.)
I like to use the diode check, as do not have to look at the screen. Using this and the "bundling" technique, and you can soon locate the short. Have done this in many control cabinets.
Can use Ohm mode to see level of resistance as you described. The light bulb check does help to identify a short as opposed to a flow to ground through another component, but I have seen where using the bulb actually created enough working load that it burned the few wire strands that were contacting the ground, and then went out. Now you measure to ground, and the wires that had shown a short do not, and you have still identified the faulty wire.
Of course, back in the old days, many of us did not have multimeters and it was standard practice to use bulbs for testing, including to trace wires, etc. on our automobiles.
I agree. It's nice to see an example of a well run and methodical investigation into a failure. So often, someone goes charging off towards a fix without proper information: an approach I've often heard described as "ready"-"shoot"-"aim". Well done and well described.
putting a higher wattage lightbulb is a trick that I was taught way back in the 1950's, when we had fuses at home and it was a great saver. I used that exact technique just this past Monday for servicing a house-wiring compaint that the circuit breaker would not stay reset.
The faster way to find the short would have been using the "divide and conquer" approach, which would be to split the hundred terminals into two groups and check each for shorts, then split the shorted group in half and check again. Just two checks and disconnecting three places cuts the number of suspects down to 25 from 100.
Of course, in some machines the switches circuit feed wire is daisy-chained through the remote wiring, which can make it a bit more work because of needing to open remote boxes.
The one other technique that I have seen is to use a hundred watt lamp with a flasher and a clampon ammeter to determine which wire is drawing the current. That method allows for checking groups of wires without any unhooking, which sometimes reconnecting wires can be a pain.
Of course, good controls design would always separate output device power feeds from sensor switch feeds. That way the E-Stop could switch off all the motion drive functions.
Some of the power wires went to operator panels, some to sensors, some to solenoid valves. Some proxi sensors have an LED indicating the sensor has power, and some others have an LED to indicate it is detecting the target. Any section of the machine that had LED's on had to be okay. When I noticed sensors without LED's on, I just had to look more closely at that area. It just happened that the sensor had obvious damage from weld expulsions, and was in a location where it was readily visible. If the sensor had been hidden, or there had been another sensor that was also shorted, the story would have been longer.
Sounds like you have some great instructors, Gsmith120. This is a consistent theme in the Sherlock Ohms blogs. Logic used with discipline and thoroughness seems to be the specical sauce for solving engineering problems.
By experimenting with the photovoltaic reaction in solar cells, researchers at MIT have made a breakthrough in energy efficiency that significantly pushes the boundaries of current commercial cells on the market.
In a world that's going green, industrial operations have a problem: Their processes involve materials that are potentially toxic, flammable, corrosive, or reactive. If improperly managed, this can precipitate dangerous health and environmental consequences.
With LEDs dropping in price virtually every year, automakers have begun employing them, not only on luxury vehicles, but on entry-level models, as well.
From Dell / Intel® New Paradigms in Design Work Scott Hamilton, vertical market strategist for Dell Precision workstations, 5/2/2013 5
Early in my career, I worked as a draftsman and remember the days of drawing on vellum with numbered pencils and Mylar with plastic lead. This was a fun experience in the sense that I ...
I've been using workstations for more than 10 years and love finding ways to get more performance from my system. With demanding professional applications that require more power each ...
A lasting memory from my first job as an engineer in an auto assembly plant is standing on hard concrete at six in the morning, vending-machine coffee clutched in hand, listening to ...
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
To save this item to your list of favorite Design News content so you can find it later in your Profile page, click the "Save It" button next to the item.
If you found this interesting or useful, please use the links to the services below to share it with other readers. You will need a free account with each service to share an item via that service.
Tweet This
3 
