snipped-for-privacy@hotmail.com fired this volley in news: snipped-for-privacy@googlegroups.com:
If you even slightly understood the situation you're using as an "example", you'd have never said that. I guess they don't teach the concept of a "Faraday cage" in 'electrical school'.
Lloyd
There's no need to understand or remember EVERY SINGLE THING taught in any school, just to accept advice and get surge arresters for your circuitry like others do to avoid getting blasted. What do you use to think with half of the time, anyway?
USB2 is slow and USB3 is new. Neither can keep up with a good hard disk, let alone the current or next-generation of flash drives.
Rather, if you plan a big bunch of disks connected, you should look at SAS/SATA RAID systems; one card with two connectors can support four to eight SATA(internal) or eSATA (external) drives with good throughput. Don't get the high-price cards with full RAID support, let the pros buy those, and buy their old cards on eBay...
Second-best is to use Firewire, which can daisy-chain dozens of external drives from a single port.
Most of the good used ones will ber SCSI though. Nothing wrong with SCSI - fast and strong, not like in the early days when it was just a short-form for "incompatible"
Current state of the art is 4tb for best price point and reliability. There have been some totall atrocious 2 and 3 tb drives on the market. The 3 terrabyte Seagate garracuda was a terrible drive
- 1 in 4 failure rate under warranty. The 4tb Barracuda appears to be rock solid. The HGST 4 terrabyte appears to be among the best on the market at the present time. (Formerly Hitachi)
walter snipped-for-privacy@post.com fired this volley in news: snipped-for-privacy@googlegroups.com:
Uh, huh! Just "accept advice"... right. Don't remember what they taught you for good reasons... right.
Most guys who are successful at any technical endeavor don't think "half the time", they think "all the time" on the job.
Who said anything about NOT using surge arrestors? You use EVERY tool at your disposal -- including your brain, if you have one. Unfortunately, many don't do that last... they work strictly on 'muscle memory'.
Lloyd
And find a Master Electrician if you want something like that.
Fair enough.
If you had used a suitable surge suppressor and it failed then, causing all that damage, then that should look like a product liability lawsuit. Have you bothered to check into it?
(not that it's even my concern)
walter snipped-for-privacy@post.com fired this volley in news:57840989-9c84-4ab9- snipped-for-privacy@googlegroups.com:
Yes, actually. Since the power mongers expressly exclude "direct lighting strikes to the incoming service" as a covered instance, my attorney said all it would do was "cost me time and money" -- enough of which I'd already spent.
Lightning GROUND rods (never, ever, ever pointy lightning rods on the roof!), arc-gap arrestors, gas discharge arrestors, MOV surge arrestors, &c just are not 'full protection' against a multi-MW bolt directly to the service. It's not the same as when it hits even as little as a block away.
The only way to obtain relatively good protection is with a long-throw knife switch on all three incoming conductors; and even that's not a 'sure bet'. The best protection to your equipment is to make sure that every single item is physically disconnected from power during a weather event, or when you're away. So now, everything we have, including previously hard-wired equipment has a PLUG, not just a 'disconnect'. It's a pain... but it works. Doesn't protect the infrastructure, though. Nothing does.
Lloyd
Gunner Asch on Sun, 08 Mar 2015 11:10:07 -0700 typed in rec.crafts.metalworking the following:
Now now, don't be hard on him. It isn't that he is unlikely to have completed 7th grade, but that his education ceased about then. After all, it is possible for one to "graduate" from college no smarter than when one started - possibly even less so. So he recalls those years he spent as a college sophomore as the best years of his life, at least as far as he can recall.
-- pyotr filipivich "With Age comes Wisdom. Although more often, Age travels alone."
pyotr filipivich fired this volley in news: snipped-for-privacy@4ax.com:
Pyotr, that was good! I had to read it twice to 'get it'!
Lloyd
I guess you never learned that in a lightning prone system always use a DC grounded antenna system a folded dipole for example otherwise the lightning takes a partial path through the center conductor of the coax and travels to the transmitter blowing your relay.
Several of the towers I serviced equipment at were grounded to R56 spec, which was
I got out of the business when Micors came out. I went into aviation electronics. I had worked on many HT 180's, Twin V 44 UHF and all the other stuff Motorola made. I maintained equipment on every tall building in NYC including the Empire state bldg. Chrysler building Pan Am building, and many others as well as many in NJ. so I do have a little experience with lightning hitting antennas.
It all comes down to having a place for lightning to go directly to ground so it doesn't take stray paths into the the equipment blowing something out.
John
"Lloyd E. Sponenburgh" on Sun, 08 Mar
2015 20:19:37 -0500 typed in rec.crafts.metalworking the following:Tweren't just the sixties which, if you remember them - you really weren't fully experiencing them.
-- pyotr filipivich "With Age comes Wisdom. Although more often, Age travels alone."
Wow, I see the 7th grade reminded you of something that was probably always on your mind. You are too, too funny. Are you into video games or something?
ARTICLE 280 Surge Arresters
I. General
280.1 Scope. This Article covers the installation and connection requiremen ts for surge arresters that are permanently installed on the line side of s ervice equipment.Author's Comment: According to Article 100, Service Equipment is the necess ary equipment, usually consisting of a circuit breaker(s) or switch(es) and fuse(s), connected to the load end of service conductors, and intended to constitute the main control and cutoff of the supply.
280.2. Definition. Surge Arrester. A protective device for limiting surge voltages by dischar ging or bypassing surge current, and it also prevents continued flow of fol low current while remaining capable of repeating these functions.280.3 Number Required. Where used, a surge arrester shall be connected to each ungrounded conduct or of the system and a single surge arrester shall be permitted to protect all of the line conductors.
280.4 Surge Arrester Selection. (A) Circuits of Less Than 1000 Volts. The rating of the surge arrester sha ll be equal to or greater than the maximum phase-to-ground voltage at the p oint of connection.Surge arresters installed on circuits of less than 1000 volts shall be list ed for the purpose.
FPN No. 2: See the manufacturer's application rules for the selection of an arrester for a particular application.
II. Installation
280.11 Location. Surge arresters shall be permitted to be located indoors or outdoors.280.12 Routing of Connections. The conductors for the surge arresters shall not be longer than necessary, and unnecessary bends should be avoided.
III. Connecting Surge Arresters
280.21 Installed at Service Equipment. The grounding conductor for the arrester shall be connected to one of the following locations: (1) Grounded (neutral) service conductor. (2) Grounding electrode conductor. (3) Grounding electrode for the service. (4) Equipment grounding terminal in the service equipment.280.22 Installed on the Load Side Service Equipment. A surge arrester shall be permitted to be connected between any two conduc tors - ungrounded conductor(s), grounded conductor and grounding conductor.
280.25 Grounding. Grounding conductors for surge arresters shall not be run in metal enclosu res unless the metal raceway is bonded to both ends to the grounding conduc tor.Article 285 - Transient Voltage Surge Suppressors (TVSSs)
I. General
285.1 Scope. This Article covers the installation and connection requiremen ts for TVSSs that are permanently installed on premises wiring systems. Fig ure 285-1 285-01 cc285-01.cdrAuthor's Comment: The scope of Article 285 applies to devices that are list ed as TVSS devices. It does not apply to devices that incorporate a TVSS de vice, such as a cord-and-plug connected TVSS unit, a receptacle, or an appl iance that has integral TVSS protection. For more information about TVSS de vices, visit
285.3 Uses Not Permitted. A TVSS shall not be used for: (1) Circuits exceeding 600 volts (2) Ungrounded electrical systems (3) Where the rating of the TVSS is less than the maximum phase-to-ground voltage at the point of connection.
FPN: For further information on TVSSs, see NEMA LS 1-1992, Standard for Low Voltage Surge Suppression Devices. The selection of a properly rated TVSS is based on criteria such as maximum continuous operating voltage and the m agnitude and duration of overvoltages at the suppressor location.
285.4 Number Required. Where used, a surge arrester shall be connected to each ungrounded conduct or of the system.285.5 Listing. A TVSS shall be a listed device in accordance with UL 1449.
285.6 Short Circuit Current Rating. TVSS devices shall be marked with their short circuit current rating, and they shall not be installed where the available fault current is in excess of that rating.WARNING: TVSS devices of the series type are susceptible to high fault curr ents if located near service equipment, and a hazard would be present if th e device rating is less than the available fault current.
II. Installation
285.11 Location. TVSSs shall be permitted to be located indoors or outdoors.285.12 Routing of Connections. The conductors for the TVSS shall not be any longer than necessary and unnecessary bends shall be avoided.
III. Connecting Transient Voltage Surge Suppressors
285.21 Connection. Where a TVSS is installed, it shall be connected as foll ows: (A) Location. (1) Service Supplied Building or Structure. A TVSS can be connected anywhe re on the premises wiring system, but not on the line side of the service d isconnect overcurrent device. Figure 285-2 285-21A1 cc285-02.cdrAuthor's Comment: Care must be taken to ensure that no more than one conduc tor terminates on a terminal, unless the terminal is identified otherwise [
110.14(A)].Exception: A TVSS device listed as a surge arrester in accordance with 280.
4(A) can be connected to the line side of the service overcurrent device.Author's Comment: TVSSs are listed to be located only on the load side of s ervice equipment. TVSS devices cannot be installed on the line side of the building or structure overcurrent device because of the concern that they m ight be exposed to lightning-induced surges.
(2) Feeder Supplied Building or Structure. A TVSS can be connected anywhere on the premises wiring system, but not on the line side of the building or structure disconnect overcurrent device.
(3) Separately Derived System. A TVSS can be connected anywhere on the prem ises wiring of the separately derived system, but not on the line side of t he separately derived system overcurrent device.
(B) Conductor Size. Line and ground connecting conductors shall not be smal ler than 14 AWG copper.
(C) Connection Between Conductors. A TVSS shall be permitted to be connecte d between any two conductors - ungrounded conductor(s), grounded conductor and grounding conductor.
285.25 Grounding. Grounding conductors for surge arresters shall not be run in metal enclosu res unless the metal raceway is bonded to both ends to the grounding conduc tor.
Motor-generator. End of discussion.
rangerssuck fired this volley in news:e8c42951- snipped-for-privacy@googlegroups.com:
How does that protect infrastructure -- or the motor?
It does narrow your losses to only the motor, but it would take one HOG of an M/G set to run my shop, and cost me yet another 30-40% in power.
LLoyd
The real isolation method is the flywheel method. Electrical to mechanical that doesn't change with fluctuations.
AC mains drive massive multi-ton rock that spins. On that shaft is a AC (generator) alternator. It generates the AC in single or three phase. If the external AC shuts down, the rock keeps turning. It turns for a long time without input power. So brown outs and twinkles are never seen on the real load because the rock absorbs small and large changes.
Cray Research used them for their buildings. Massive spinning disks of rock.
Mart> rangerssuck fired this volley in news:e8c42951-
Well ... our lab had something similar to make sure that the fume hoods would not suddenly stop when some rather toxic gasses were in use there. It also protected the rest of the building, too.
But -- it was not a separate motor and generator. Instead, a
*big* permanent magnet rotor three-phase motor kept the flywheel (steel, not rock in this case) spinning. About 4' diameter by about 8" thick, IIRC.On the other side of the flywheel was a flexible coupling, an electro-magnetic clutch (brake assembly from a B-58 I believe) and a big Detroit Diesel.
A cabinet of electronics monitored the power. If the frequency or voltage drifted out of spec, the clutch was allowed to transmit torque, and the flywheel started the Diesel *right* *now*. In the meanswhile, the permanent magnet rotor three phase motor became a generator, and kept the building going. The flywheel for a little while, and then the Diesel
Now there were three *big* breakers on a panel. One from line to the motor, one from the motor to the load, and one from line to the load. Once, someone switched off the line to motor breaker, and then switched it back on -- without the benefit of the electronics in the cabinet. Thus it connected about the time the phase had drifted 180 degrees. It drew a *lot* of current, and blew out the fuse on the pole pig, and another closer to the substation on post. :-)
Enjoy, DoN.
And at demo time, those breakers and that 500 wire and bus bars aren't bad for spending change.
The object of the Cray way was smooth power all of the time. If there was time to power down ok. But spikes and sags were not wanted when measuring signals and building monster machines.
Yours was a UPS of sorts as long as the 'oil' was flowing.
Mart> >> The real isolation method is the flywheel method. Electrical to
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