Power Cable Protection & Sag Detector
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Lack of maintenance causes the belt to cut through cables under the machine
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Safety issue: 480 Volt cable runs under the machine
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Solution: developed mechanical guard for cables and worn belt reporting system
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Results: $200 per unit COTS solution with a total cost of $32,000 nationally
Power Cable Project Scope
The induction lines of one of the machines belt would sag over time causing it to drag across a cable trough and some of the cables would be sticking out,causing it to be worn down over time. Sometimes the first sign a belt needed to be replaced was a signal cable failing. One of the other cables in the trough was a 480 volt power cable that if severed could cause death, which has not happened yet but needed to be prevented from happening.
To prevent this from happening and also alert operations when the belt had worn out so that it could be replaced without interfering with the machine's operation, I looked at possible solutions to safeguard the cable by making it impossible for the belting to slide across the cable trough. For this I settled on a flow roller as in the image above, the next issue was figuring out how to mount it so that it would not interfere with the belt as well as how to detect when the belt had worn out enough to warrant it being replaced.
For mounting I had a flow roller ordered to our site. I then went and mocked up a prototype on the induction so that I could figure out the spacing needed between the flow roller and the support brackets that held the cable trough on the machine. To do this, I used a shimming method to get the spacing correct so that the entire cable trough was protected and the rollers didn't interfere with the belt.
I then created a BoM using COTS parts that had the correct height requirements c-channels specifically, for mounting the flow rollers. I modeled this in Inventor-Pro so that the stack mock-up could be repeated easily by anybody when given a picture of the design.
The next issue was developing a way to detect when the belt had degraded to the point that it was rubbing on the flow rollers and needed to be replaced. To accomplish this I looked at a series of whisker switches and settled on a wire version due to its resistance to vibrational energy and being a sealed System since that is a requirement that comes up often with the post office. The system required 2 of these switches due to the belt being partially by frame cross members. The switches were located at the middle point between cross members since that is where the sag would be most evident.
I then pitched the design to the postal customer and showed them the documentation. The overall cost of the system was about $200 per induction line. The whisker switches were incorporated directly into the machine software that would send out a signal when it was time to replace the belts. The project was then rolled up into a package for updating that particular machine family nationally that was led by one of our external suppliers. The total cost of deploying the project was $32,000.
