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Can't use a clamp meter on DC wiring because: loving electromagnetism, how does it work?
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Sep 17, 2013 21:24
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kastein posted:Can't use a clamp meter on DC wiring because: loving electromagnetism, how does it work? grover fucked around with this message at 22:03 on Sep 17, 2013 |
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Sep 17, 2013 22:00
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DC clamp meters are indeed a thing
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Sep 17, 2013 22:06
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The Proc posted:DC clamp meters are indeed a thing  I completely forgot about that... and go figure, I was designing something that uses a related effect (anisotropic magnetoresistance, using the Honeywell HMC1512 sensor) loving yesterday.
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Sep 17, 2013 22:21
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Fluke 27/28 are pretty good meters too, especially if you have a rough environment. My 3000A DRANFLEX rings won't work on DC.  Anyone have good/bad experience with Gossen-Metrawatt products? I think they just bought out Dranetz. Three-Phase fucked around with this message at 23:37 on Sep 17, 2013 |
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Sep 17, 2013 23:32
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M_Gargantua posted:I have a personal love of the 289. Every feature I've ever needed. Welp, just did some research and I'm minutes away from calling my distributor and dropping a wad of cash on one of those. That's a seriously impressive meter. I think the logging capability is what grabs me. Seems really useful for the many times where I've needed an extra set of hands to watch a signal while I try to replicate a problem. That said, what do you guys recommend for a cheap back-up meter? Something small and simple for basic measurements for when I don't want to haul my expensive rear end meter to somewhere it might get busted (e.g. top of a silo), but at the same time something that won't explode in my hands in the event of a transient.
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Sep 18, 2013 14:50
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DaveSauce posted:That said, what do you guys recommend for a cheap back-up meter? Something small and simple for basic measurements for when I don't want to haul my expensive rear end meter to somewhere it might get busted (e.g. top of a silo), but at the same time something that won't explode in my hands in the event of a transient. Fluke has a smaller meter that has a built-in current clamp that I see a lot of electricians using.
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Sep 19, 2013 11:04
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Three-Phase posted:Fluke has a smaller meter that has a built-in current clamp that I see a lot of electricians using. And it sucks! If you want a multimeter with less features, get a 175, 177 or 179, they are great for general electric and automation uses. I use a 177 in my daily work, it has all the features I need. They're sturdy too! I also have a neat Fluke 771 mA clamp ammeter. Measures 0-20mA, great for faultfinding!
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Sep 21, 2013 17:06
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Yeah, the one particular issue I've had with that cheaper meter is that the Ohm readings on that device are accurate to only one point, no decimal points. With their other meters you can zero out the lead resistance and take fairly decent measurements to the tenths of an Ohm. I am hoping that Dranetz will eventually ditch those stupid CF cards on their power quality devices (Power Visa, Guide, and Explorer series) for more modern (and faster) SD cards. You would think a higher-class rated SD card would have no problem recording four voltage (A-N, B-N, C-N, N-G) and four current waveforms (A, B, C, N) at a 2500 samples/sec or so resolution. I really want to just call their New Jersey office and flat-out say "Hey, 1995 called, they want their CF cards back." It's frustrating. Three-Phase fucked around with this message at 02:18 on Sep 22, 2013 |
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Sep 22, 2013 02:11
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CF isn't so bad, at least card readers are still readily available. One of our IR cameras uses a PCMCIA memory card. 
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Sep 22, 2013 02:27
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They make CF cards that are at faster than SD.  It isn't a media bandwidth issue. It could be a interface bandwidth issue, or they just want you to buy a more expensive product to get more features. I tried to find out what speed they supported on the Power Visa, but it doesn't say. I did notice they tried to say you could use only Dranetz brand CF cards. Yeah, right. Bosch-Rexroth tries to do the same thing, and even uses a messed up partitioning scheme to force you into it. I fixed that with dd. No more $1500 replacement CF cards.
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Sep 22, 2013 14:44
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Guy Axlerod posted:They make CF cards that are at faster than SD. Wow, I had no clue that they made CF cards that were that fast. Yeah, the card branding did bug me. However if you have a 4GB card you can store a lot of data on it. I think that the individual log files are limited, and it really depends on both your intervals for recording RMS data as well as your triggering parameters to record RMS and waveform data.
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Sep 23, 2013 00:21
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Three-Phase posted:Wow, I had no clue that they made CF cards that were that fast. They’re still common in professional camera, where high write speed matters. CF cards are slowly on their way out. It’s a petty reason, but I’m going to miss them because I like their size. They’re easier to handle than SD cards, but they’re still small enough that they take up an negligible amount of space compared to the equipment with which I use them.
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Sep 23, 2013 01:47
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What kind of education goes in to becoming an industrial electrician? Is it guild\union based, or usually college? This stuff is absolutely fascinating.
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Sep 24, 2013 04:32
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CF is also pin compatible with IDE, i imagine that keeps them around for some reasons (like as replacement parts of ancient computers still running somewhere in some factory).
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Sep 24, 2013 09:06
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SSH IT ZOMBIE posted:What kind of education goes in to becoming an industrial electrician? I've worked with industrial electricians, but I am not sure about this. I'll ask some of them if I get a chance! They're an interesting and diverse group of people. There are technical school courses that cover this.
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Sep 26, 2013 23:14
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I was tipped off about some job openings at my company by some family that already worked there. I went to a 2 week unpaid tryout to evaluate basic mechanical/mental skill, and to weed out people who cant follow directions or work under pressure, or those who can't handle claustrophobic conditions or climbing 40' structures. They picked a handful out of ~500 off-the-street applicants and sent us to college, which was both classroom study and real world experience.
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Sep 27, 2013 20:22
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SSH IT ZOMBIE posted:What kind of education goes in to becoming an industrial electrician? Technicians typically have some formal college education, and get to do a lot the more technically challenging jobs, like setting up or troubleshooting complex industrial power systems, controls, etc. The engineers who design those complex industrial power systems have at least a 4-year degree. The engineer knows what to do; the electrician knows how to do it. The engineer might want a 1200A feeder cable; the drawing might specify a certain number, type and diameter of conduit and number & type of wire, and show how it's to be connected; or it may just draw a line and say "1200A". It's up to the electrician to figure out how to route that conduit, what fittings to use and where, how to support it, where to put the knock-outs for the equipment, how to pull the cable in, and so on. So the electrician has to be up on code as well as knowing the techniques for doing things like pulling in large industrial cables, and other incidentals like how to order cable, how to know how much to order, what the best cable lube is, and so on. Then the technician will come in and throw a hi-pot on it and bitch about how you did it wrong and exceeded the tensile limits of the cabling, and the engineer will look up and say you routed the conduit where the HVAC guy needs to run his duct and you have to move it and OBTW you used the wrong fittings... and the project manager makes you do it all again. Because that's the life of the industrial electrician 
grover fucked around with this message at 00:42 on Sep 28, 2013 |
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Sep 28, 2013 00:26
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It's also very important for engineers to talk to and listen to their electricians and technicians. I've seen some infallible engineers who arrogantly considered these people to be in a "class below them", while others had an excellent working relationship with them. The best situations are where people in different parts of the work look out for one another. I had a memorable situation where I was working with a small crew putting in HV terminations. Nobody had a lot of experience in this, but we all worked together to make sure we did everything correctly. I took the time to go over what we had to to, and why we had to do it. (It ultimately wasn't that hard, but we were all extra careful.) On the other side, I've seen situations, particularly if you're an engineer troubleshooting, the electricians and technicians may see you as an unwelcome interloper. I've had situations where I had to clearly tell the electrician "I'm not trying to be a hardass, but to do this safely, we must perform steps A, B, and C, in this order, because I don't want to damage the equipment or worse risk injury to anybody. I know it'll take an extra three minutes." Come on guys, I'm here to help fix your stuff! Also, I am extremely thankful that I haven't really run into this, but being an engineer, technician, or an electrician and having a substance abuse problem do not mix. If you have a hangover call in sick, don't show up in a daze. Three-Phase fucked around with this message at 03:24 on Sep 28, 2013 |
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Sep 28, 2013 03:19
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https://www.google.com/maps/preview...i955!4f35&fid=7 I saw the "what is this" chat earlier. I'm curios as to what type of plant this is. They're also building a bunch of stuff in that empty field south of the round. They've been updating/maintenence on the giant towers SW of it—you can see near the plant they've been bulldozing through farmer's fields.
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Sep 29, 2013 02:43
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thylacine posted:https://www.google.com/maps/preview...i955!4f35&fid=7
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Sep 29, 2013 03:10
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Thanks. Interesting. I bet a lot of these gas fields go there: https://www.google.com/maps/preview...68!4f13.1&fid=7
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Sep 29, 2013 03:14
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grover posted:I was hoping someone would pipe up with actual specific knowledge about this, but a high school diploma is all you really need. Most of the industrial electricians I know have had some type of formal trade school (vo-tech or comparable) supplemented with a period of apprenticeship, either as a formal apprentice or as an electrician's helper. While you're doing this, work on your licensing requirements and study up for the journeyman's exam. Once you pass the journeyman exam and get licensed, you're officially (and legally) an electrician. Most people in Canada will go to College for electrical which helps them with landing co-ops and gives them some apprenticeship hours. Although the state of the industry is very weird, I'm always reading and hearing that there is a shortage of tradespeople in the industry, when the reality is that no-one wants to hire apprentices. My father just retired from being an industrial electrician about 6 months ago and he's been called to come back on contract 6 times. He just tells them to hire some young guys. I always find designs can go either way, sometimes I'll spend the time (or rather the project requires me to) to specify connectors, conduits, etc. Then when it's all said and done the electrician will just install what he wants because I on't know what I'm talking about when it comes down the the knitty gritty details (which is partially true). I've been toying with the idea of doing an apprenticeship (if i can find one) to get my industrial electrician's ticket once I get my professional designation as an engineer. I've heard that an engineer with a trade license is pretty valuable, does anyone have any experience doing something like this? Plus it would be nice not to have to sit at a desk for most of the day.
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Sep 29, 2013 15:53
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Found a video of these guys showing us a really old , fairly huge breaker. I need to get in touch with these guys in Cleveland sometime.
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Oct 2, 2013 02:24
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Liberty ships had some crazy scary switchgear. 120VDC, 20kW. Click for bigger:    this ship (SS Jeremiah O'Brien) still goes to sea, and still uses this switchboard for main power
grover fucked around with this message at 11:30 on Oct 2, 2013 |
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Oct 2, 2013 03:05
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Every time I hear anything about liberty ships, it's  in nautical form.I guess that's what happen when you design something quickly with the only consideration being how quickly they could be mass produced.
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Oct 2, 2013 03:16
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Speaking of circuit breakers, here is a 345kV CB I took a picture next to at work. If you hold your hands up you can almost feel it tingle.  If anyone is interested I can post some other photos I grabbed of the substation.
freezepops fucked around with this message at 04:23 on Oct 2, 2013 |
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Oct 2, 2013 04:20
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That's every day of my life, freezepops!
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Oct 2, 2013 12:52
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freezepops posted:
Please do, I find substations to be oddly facinating.
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Oct 3, 2013 03:55
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 ~400MVA 138kV transformer. The trucks give you a good idea of the size.  138kV control house.  345kV breakers again, and off to the left you can see some air core reactors (soon to be replaced).  Here you can see all the 345kV lines in the substation.  A ~650MVA transformer, you can see oil retention pool in case of a leak. The rusted can at the bottom is a 1 gallon paint can. Sorry for the bad crop job, my finger got in the way.
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Oct 4, 2013 04:18
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Wow, 650MVA is pretty much a behemoth transformer. I see a lot of the blue SEL (Schweitzer Engineering Laboratories) relays. The SEL relays have a pretty impressive warranty on them and are way more "robust" than their GE counterparts. I've had issues in the past with GE's relaying, they are pretty easy to install/use but they are not as customizable and I have reliability concerns.
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Oct 4, 2013 11:09
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I love SELs. Those and Form 4Cs are my favorite to work on, especially next to the dinosaur relics I usually see.
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Oct 4, 2013 14:20
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I've never seen them, do they sell in the US only? How do they compare to European ones like ABB / Siemens /
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Oct 4, 2013 15:52
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Just a quick question - am I correct in assuming if you own a residence, in an area that is zoned for standard houses, no matter how much money you offer the power company they cannot/will not do something like installing a separate three phase transformer (120/208, 277/480, or 347/600) into your home to supplement your existing Edison 120/240? The only exemption I could see for this is if someone was way out in the country on a farm and they needed more power for equipment. But not in a suburb.
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Oct 8, 2013 21:09
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grover posted:I've got an amprobe AC50A AC leakage clamp-meter I use for grounds and other low current stuff (the small clamp makes it nice for small circuits in tight panels, too). Works pretty good on AC; not sure how it would be on DC controls. It's also conveniently small, though it just feels cheaply made. Runs about $300, though; if you don't need to go down to 0.1mA, you can probably find something cheaper. Grover you get a lot of poo poo and undeservedly so sometimes, but aren't you a loving electrical engineer? Come the gently caress on, man. EDIT: Oh great, now I look like an rear end in a top hat. Carry on grover, this was one of the undeserved times. For content, would there be interest in seeing the rotor out of a 8MW generator out? Comrade Blyatlov fucked around with this message at 01:07 on Oct 9, 2013 |
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Oct 9, 2013 01:01
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Nah, the datasheet lists no AC, not a hall-effect CT. 0.1mA isn't bad though. Two Finger posted:For content, would there be interest in seeing the rotor out of a 8MW generator out? Yes. Very yes.
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Oct 9, 2013 01:22
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Three-Phase posted:Just a quick question - am I correct in assuming if you own a residence, in an area that is zoned for standard houses, no matter how much money you offer the power company they cannot/will not do something like installing a separate three phase transformer (120/208, 277/480, or 347/600) into your home to supplement your existing Edison 120/240? In most suburbs, there's only one phase per street. The subdivision will have 3-phase run by it, and only one phase will go down each street. It's not unheard of for people to find property where a couple of the single-phase lines get close and get an open delta. I saw one not too far from my house recently. Looked like a standard property, but with two transformers on the pole and four buried lines going down. I'll try to get a picture at some point. Two odd-sized transformers up there really caught my eye. He probably just bribed someone at the utility, or he or his cousin works there.
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Oct 9, 2013 01:49
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So, the NSA is having a bad time with electricity:quote:The first arc fault failure at the Utah plant was on Aug. 9, 2012, according to project documents. Since then, the center has had nine more failures, most recently on Sept. 25. Each incident caused as much as $100,000 in damage, according to a project official. I was under the impression arc faults were rather uncommon and real day-ruiner, not something that happens nearly once a month in a single facility. What might be going on over there?
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Oct 9, 2013 01:53
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That sucks and should be investigated, but that equipment can be repaired or replaced. Was anyone injured? I'll take a million dollars in facility damage with no injuries over one worker getting debilitating arc flash injuries any day of the week. Whenever I hear anything in the news about "third degree burns over 50% of their body" I then think of "skin debridement tanks" and it makes me cringe more than anything else I can possibly imagine.
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Oct 9, 2013 02:04
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Unfortunately the article Ars is citing at the Wall St Journal is paywalled, so its not clear if anyone was injured. Say what you will about the NSA, but I also hope no one got injured. I just wonder if they are using tons of completely custom equipment, or if there is just terrible contracting going on. Seems like arc faults are the sort of thing that shouldn't happen, but really shouldn't happen 10 times in a year at a single facility. 50,000 manhours tracking down the problem(s) at least shows they are trying to resolve whatever issues there may be. Are arc faults usually an equipment or a personnel problem?
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Oct 9, 2013 02:16
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