# How do I learn to read electrical schematics?



## HMF (Jan 5, 2012)

Here is a schematic of a milling machine wired to a VFD.
Can anyone explain the symbols and exactly which wires are running where for newbies wiring machinery?
What controls (switches) are being used and what do they do?


View attachment 32279


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## Tony Wells (Jan 5, 2012)

That's a broad subject, Nelson. Can you identify anything on that, or are you needing a markup of all the components? That .jpg could be labelled and annotated and returned to you or posted here again.


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## DMS (Jan 5, 2012)

Great work Jim.

To Nelson, Jim did a good job of describing the stuff you have, but if you run across new things, this page may help

http://library.thinkquest.org/10784/circuit_symbols.html


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## HMF (Jan 6, 2012)

Jim-

That is a wonderful guide- thank you!

I am perplexed reading these things.


Nelson


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## 12bolts (Jan 11, 2012)

Jim B. said:


> Here are most...


You missed a couple.

Cheers Phil


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## pdentrem (Jan 11, 2012)

12bolts said:


> You missed a couple.
> 
> Cheers Phil



Actually the electricain that we use, was on another job site and was repairing electrics after a coolant fire caused some damage. His brother had to go to the disconnect and made a remark about finding "3 no blow fuses" installed. The disconnect was for a 600V 3PH CNC milling center.

I asked about what he meant be "no blow" and he pulled out 3 machined pieces of steel that fit the fuse holders just like fuses would of. He stated that the time required to make these was likely as much as buying the right fuses in the first place. The scary part was the next level of protection after the "no blows" was the main fuses for the whole building! If you were hoping that the disconnect would trip to make the equipment safe would of found that it was the 400 amp fuses were the only safety in the building and you were dead and on fire as well. Stupid and very deadly.


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## Tony Wells (Jan 21, 2012)

Nelson, here's one for you to practice on:


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