Wallpapers from The Verge | Lrd12 Overload Relay

They all have a ceramic rod or coil wrapped with nichrome wire that turn red hot. A vaccum forming table design I looked at used ceramic rods made the same way with reflectors to evenly distribute the heat. I believe all of the above (I did not verify if the table was) were UL marked.

Most people posting seem to have three stories, I only have two. Hard to believe I learn faster than you all; I must have just forgotten the other times.

As an example, I went to my mom’s place in the mountains, plugged in my Clarity PHEV using a 100 foot 12 gauge extension cord to an outdoor outlet that looked corroded. After an hour I checked the plug and it was hot of course, so I stopped charging, cleaned the outlet thoroughly, plugged it back in and it was cool (or just slightly warm) to the touch along the entire cord and outlet through the charging process. Using the extension cord is dangerous as there is no thermal sensor in the extension cord at the outlet or could be damaged internally. The corroded outlet was dangerous (and could have very likely melted out had I not checked it). The cord can get easily damage.

Earthing is thus a vital part of power distribution safety. The only snag with open equipment on your bench is that any earth connection becomes a valid part of the return circuit for the power, and since that earth connection can come through you, that’s dangerous. The isolating transformer breaks that earth circuit for your bench, thus removing that particular hazard. The upshot of this is that you can safely touch either one of the two wires and because there’s no path to ground, you won’t get zapped. (Touching two wires completes the circuit. You still have to be careful!) Isolation transformers are also used to lift the ground so that you can connect mains circuitry up to your oscilloscope, even though the black probe clip is connected to earth ground.

Heat damage from increased resistance is pernicious. P = I^2 * R. At 24 amps, a resistance of a mere tenth of an ohm is 57 watts – almost twice as much as a pencil soldering iron! That’s why it’s important to get those crimps done right and inspect them frequently for signs of degradation. I will readily concede that I am not equal to a manufacturer in terms of consistency and reliability of crimps, even with a ratcheting tool. The only way I can make up for that is keeping an eye on things to catch early degenerative changes before things get out of hand. Part and parcel of building high powered electrical equipment by hand is being ever vigilant when using it.

i have 300w 12v silicon heat bed i just use a 700w pc power supply and 70A relay it heats bed over 100 oC in about a minute no problem

Voltage TransientsVaristors feature high durability, which is essential for withstanding repeated high-peak pulse currents and high-energy surge transients. They also offer a wide voltage range, high energy absorption, and fast response to voltage transients. Peak current ratings range from 20 to 70,000 A, while peak energy ratings range from 0.01 to 10, 000 J.

Wikipedia states most of mainland europe is on TN−S. “This arrangement is a current standard for most residential and industrial electric systems particularly in Europe”, if thats wrong, someone should fix it, preferably someone who has a authoritive position and can quote standards https://en.wikipedia.org/wiki/Earthing_system

Also I have seen opto-couples where the pins have been spayed out to gain an extra 0.1″ between the rows of pins.

Using SO for internal wiring is something that I have often done — it is resilent, flexible, and high temperature. Also a joy to strip.

The third incident was also while I was working for the welding repair company. I had a previously perfectly working high-pot tester and needed to test the insulation on a transformer. The tester itself failed and shorted to the case – and I took 11kv AC to the fingers just by turning the power on. That stung a bit, but I got a new high-pot out of the deal, so a net positive.

Just make sure everything is safe and properly grounded any time you’re using electrical equipment and everything should be great. No more reaching behind the Christmas tree to unplug the lights at bedtime!