Ask me about industrial electricity 2: electric boogaloo

The Something Awful Forums > Discussion > Ask/Tell > Ask me about industrial electricity 2: electric boogaloo

atomicthumbs: Dec 26, 2010; We're in the business of extending man's senses.

I have a three-phase lathe motor. What can I do with it and a 120v single-phase home thing? Preferably, I'd like to use it in something that makes a horrible noise.

# ¿ Sep 30, 2011 19:49

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# ¿ May 3, 2024 09:38

atomicthumbs: Dec 26, 2010; We're in the business of extending man's senses.

I heard y'all like old electrical gear. I went to the historic mining park in Tonopah, NV:

Operations Stopped by atomicthumbs, on Flickr

That red building contains the hoist controls, motors, flat cable winch, and huge air compressors. I took some photos of the electrical bits with this thread in mind.

Motor starter, I think.

Westinghouse motor dataplate. I don't think "Patented '97" means 1997.

Switchgear and back of said switchgear.

Big ol' motors with big ol' windings and big ol' commutators (?)

And, finally, the pinnacle of motor speed control technology ca. late 1800s/early 1900s: a big loving bank of resistors (data plates said "rheostats"). I'd hate to be the one on the winch controls standing right next to them. Note the little control podium with the cables and handle in the last picture.

# ¿ Oct 14, 2013 03:05

atomicthumbs: Dec 26, 2010; We're in the business of extending man's senses.

Last night, around 3:00 AM, my broken UPS/makeshift power conditioner strip thing cut power to my computer and started squealing. Its battery is completely dead, and usually when the power goes out it lets out a brief blip and dies, but apparently this was a pretty severe brownout.

Luckily, this thread taught me that I should go around the house and turn off/unplug motorized stuff to keep it from burning out; the heaters were still heating, but the fans were barely spinning. My laptop and phone kept charging, and the LED light bulbs emitted a normal amount of light just fine, but nothing else worked. When I got up this morning, the power was out entirely.

Apparently there was a tree on fire a few streets away around the same time last night. What's the likely cause and effect here: transformer fails, lighting tree on fire and causing voltage sag, or PG&E's system has a brownout, voltage sag causes increased current draw in various appliances, which causes lines to heat up and sag into a poorly maintained tree?

# ¿ Jan 16, 2014 22:29

atomicthumbs: Dec 26, 2010; We're in the business of extending man's senses.

angryrobots posted:

Lots of possibilities, but my money would be on

1. Tree gets into primary line on 3 phase circuit. It could have fallen from decay, wind, weather, take your pick but it got into one of the phases. Tree catches fire during arc fault.
2. Circuit protection device opens on single affected phase; utility has 3 individual devices that do not operate simultaneously on all phases. Your home is connected to this phase.
3. The newly open phase is backfed from numerous 3 phase banks connected to the affected circuit. This backfeed does not successfully energize the open phase to full line voltage under load, giving you an undervoltage condition at your home.

This is a residential neighborhood; I don't think there's 3-phase running through there (just the standard three line 120/120/ground, whatever you call it).

Found a news article:

quote:

A wayward power line triggered a stubborn tree fire in Woodacre early Thursday.

The downed lined near 15 Maple Road ignited a blaze about 3:45 a.m. that initally was reported as a structure fire.

A county fire crew doused the fire after utility poersonnel cut the power. Three hours later, firefighters were back in action when power was restored � and the tree began burning again.

Damage was limited to the tree.

# ¿ Jan 17, 2014 01:38

atomicthumbs: Dec 26, 2010; We're in the business of extending man's senses.

DaveSauce posted:

Is there an easy way to calculate available fault current in a place where no study has been done?

Place a non-contact ammeter around a spud bar. Place the spud bar across the terminals, bus bars, or cables with the most warnings near them. Document result.

# ¿ Jan 28, 2014 08:24

atomicthumbs: Dec 26, 2010; We're in the business of extending man's senses.

I love the lamps and synchroscope :kimchi:

What's that noise in the background when they try to do the transfer? Generator being loaded down, or something else?

atomicthumbs fucked around with this message at 10:50 on Feb 1, 2014

# ¿ Feb 1, 2014 10:48

atomicthumbs: Dec 26, 2010; We're in the business of extending man's senses.

https://www.youtube.com/watch?v=ow84TU3g9bk

# ¿ Mar 3, 2014 03:22

atomicthumbs: Dec 26, 2010; We're in the business of extending man's senses.

This seems like the right place to ask, so:

I have a laser capacitor. It's 6 capacitors in a welded steel case, sharing a common ground terminal; each one is 225 uf and is rated for 1.5 kv.

The capacitor datasheet says it's rated for 4 kiloamps discharge, and 20% voltage reversal.

Working it out, a 250 us pulse would be the fastest I could discharge the thing into something without exceeding the current rating.

I have the dozen IR 50RIA120 SCRs that came with the cap, but they're only rated for 1200v and are thus lame as hell.

Is there a good high-power book I can read that would tell me:

how to switch this poo poo
how to design a pulse-forming network to get my pulse to 250 us (the cap was designed as 6 caps for exactly this purpose)
how to build one hell of a snubber to keep my hard drive crusher coil from ringing and destroying my capacitor with too much reverse voltage
how to determine the characteristics of the high voltage transformer that came with the other stuff; Rowland Precision Machining apparently ceased to exist at some point, so I have no idea what a "T-308" actually is

thanks

atomicthumbs fucked around with this message at 19:14 on May 12, 2015

# ¿ May 12, 2015 06:15

atomicthumbs: Dec 26, 2010; We're in the business of extending man's senses.

SeaBass posted:

I used to work at GA as a technical sales engineer in the capacitor group.

Where did you get the cap and what are you using it for?

I took apart a flashlamp-pumped Nd:YAG medical laser (a New Star Lasers Cooltouch II) that was due for recycling and I'm using it for destruction

# ¿ May 13, 2015 00:06

atomicthumbs: Dec 26, 2010; We're in the business of extending man's senses.

kastein posted:

Start out by using the trigger/switching circuitry off the laser you took this out of, as well as the charging circuitry, if possible.

I'm assuming the laser is xenon tube pumped however, so the output of the cap bank probably just went right to the anode and cathode of the xenon strobe, with a multi kilovolt trigger transformer ionizing the tube gases externally to trigger it, so there may really be no switching circuitry to pillage I guess.

As for actually designing one, I can't help you there, it's been too many years and I tend to shy away from that kind of stuff and leave it for more specialized analog/power engineers to worry about.

e: the SCRs I'm guessing were actually from an active rectifier bridge, probably a 3 phase one, used to charge the capacitor bank.

For switching you could consider something like krytrons (haha, good luck, they're considered a critical part of a nuclear weapon initiator) or a variety of other gas discharge tubes. They tend to be capable of switching extremely high currents economically since they're mostly obsolete, at least compared to kilovolt-plus, kiloamp-plus SCRs, IGBTs, MOSFETs, and similar devices.

Here is a great article on GDTs - http://www.electricstuff.co.uk/pulse.html

Note that they consider 3kA and 5kV "medium" power levels for krytrons. That is a pretty good sign that a device that will do the job is somewhere in this category.

Unfortunately the SCRs were the switching setup; they were set up two to each capacitor, with the whole shebang attached to a controller board (not shown):

They're only rated for 1.3kv surge each, so I won't be able to get the full 6-megawatt pulse this thing is capable of (unless I'm misinterpreting how it's laid out). Solid state is lame anyway :v:

The charge power came from a 1.5kv capacitor charger power supply (quite handy) attached to that board on the capacitor, which handles both charging and bleeding duties (also handy).

The flashlamp itself was connected in a manner I can't quite remember to another board, which has a pair of lower-voltage but still pretty big electrolytic capacitors attached to it, as well as a "simmer converter" box which apparently outputs 1200v at low current to keep the tube ionized. I'm guessing it's a 3-stage simmer > trigger > FLASH triggering process.

There was a huge honking 25-pound toroidial transformer mounted to the bottom of the laser casing, which I discovered was actually very boring when I removed its mounting ring and found out it was a 115-to-115v isolation transformer with a secondary winding that output 24v.

Thanks for the article; looks like I've got some reading to do. (I've got some thyratrons in a bag I should probably look at, but they're mostly lame low-voltage stuff.) It looks like hydrogen thyratrons and ignitrons don't cost too much on eBay, but the latter is mostly meant for switching continuous high-amperage currents.

e:

atomicthumbs fucked around with this message at 07:10 on May 13, 2015

# ¿ May 13, 2015 06:09

atomicthumbs: Dec 26, 2010; We're in the business of extending man's senses.

https://twitter.com/IslesofErin/status/757364207859986432

# ¿ Jul 26, 2016 21:35

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# ¿ May 3, 2024 09:38

atomicthumbs: Dec 26, 2010; We're in the business of extending man's senses.

https://www.youtube.com/watch?v=JeqZL7ZsUt8

# ¿ Apr 7, 2017 08:16

The Something Awful Forums > Discussion > Ask/Tell > Ask me about industrial electricity 2: electric boogaloo