Surge / Ground / Lightning
in [Home Built PC]
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From: w_tom on 6 May 2008 21:34 On May 6, 10:54 am, Jitt <tser...(a)yahoo.com> wrote: > I suppose I phrased the question badly. I wonder why a surge > would wander around looking for ground, when its available > in the box! If all grounds are same, then connect lightning rods into a motherboard ground. That would be perfect building protection because a lightning rod is grounded? Ground inside a stereo is different from ground inside a TV is different from ground on the computer case is different from ground on a wall receptacle is different from ground inside a cell phone is different from a ground inside a breaker box is different from ground in earth. Most all those grounds are interconnected and are still not the same ground. Electricity is different at both ends of a wire. That 100 amp surge seeking earth from a wall receptacle may leave the wall receptacles at 12,000 volts - again, due to wire impedance. That plug-in protector on Page 42 Figure 8 was so far from earth ground (via AC electric wire) as to be >8000 volts - a destructive path via an adjacent TV to earth. The EE Times article entitled "Protecting Electrical Devices from Lightning Transients" defines why a ground in a box is not a ground to surges. Why electricity at both ends of a wire is always different. Why that difference during a surge is so important that an effective protection makes a 'less than 10 foot' connection to earth. Only relevant 'ground' is the one that is ground to a surge. That is not an 'inside the box' ground. Typically destructive surges are an electrical connection from a cloud to earthborne charges maybe miles away - the relevant ground. If any part of that connection is via an appliance, then the appliance may be damaged. Surge protection has always been about diverting a connection from cloud to earthborne charges so that current need not pass inside the building. A protector is only as effective as its earth ground so that surges need not enter a building. No earth ground means no effective protection; means a surge creates connections to earth destructively inside a building. Any facility that installs effective protection does earthing connected, very short, via a 'whole house' type protector. Polyphaser makes a protector that has NO earth ground connection. Earthing is so critical that their protector mounts directly ON the earthing electrode - zero feet from earth ground. Distance to earth ground is critical for effective protection. Which ground? Earth ground is not found and not provide in three wire AC wall receptacles. That is a safety ground.
From: Tantalust on 4 May 2008 13:24 "w_tom" <w_tom1(a)usa.net> wrote in message news:131decf4-6a8d-42e8-a973-b71a30a7f862(a)b1g2000hsg.googlegroups.com... > On May 1, 12:21 pm, trad...(a)optonline.net wrote: >> He says appliance/ electronics manufacturers put surge >> protection inside the appliance and that is peachy keen >> and appropriate. Yet he can't explain how it is that an >> MOV inside the electronics actually protects, while an >> MOV located in a plug-in is useless. > > If trader read what was posted rather than entertain his > assumptions, then trader would understand appliances contain internal > protection. When trader misread, then trader reclessly invented MOVs > to provide internal protection. What w_tom posted is not found in > trader's wild speculation. > > With a grasp of technology, then trader would have known industry > standard numbers that defined internal electronics protection even 35 > years ago. Trader does not know these numbers. Trader then assumed > that protection must be provided by MOVs. Trader - learn technology > BEFORE knowing everything. You have no idea of protection inside all > appliances. By reading reclessly and by using wild speculation and > ignorance, trader assumes protection must be provided by MOVs. > > Protection inside appliances is integrated within appliance > design. Internal appliance protection that may be overwhelmed if a > 'whole house' protector is not installed and properly earthed. > Nothing in that paragraph discusses MOVs. MOVs inside appliances is > another trader 'wild speculation' due to knowledge without first > learning the technology. > > We earth a 'whole house' protector AND connect all protectors short > (ie 'less than 10 feet') to single point earth ground so that > protection inside all appliances is not overwhelmed. Simple stuff > that so confused trader. trader *assumed* MOVs rather than read what > was posted. trader again demonstrates insufficient technical > kowledge justifies his mockery and insult. Mythical MOV inside > appliances demonstrate that trader only reads what he wants to see; > not what is posted. > > MOVs inside appliances is another trader myth. Had trader read what > was posted or learned technology, then trader would not invent > fictional MOVs inside appliances. Why do you have this pompous attitude; constantly sermonizing down to people as if they're your little, personal kindergarten class? You read sometimes like one of those old children's "Golden Books".
From: Timothy Daniels on 4 May 2008 13:43 "Michael A. Terrell" wrote: > > All I know is that I finally kill filed him on this computer after I got > tired of reading his 'twilight zone' electrical & electronics babble. > I am a former radio & TV broadcast engineer, and if I followed > his or _wacko_tom's warped ideas, I would have had millions of > dollars worth of damage. I had a studio building and STL tower > in Leesburg Florida hit by a direct strike. It blew chunks of concrete > from the building where the rebar and threaded rods ran vertical. > It WAS an excellent example of _wacko_tom's UFER ground, > before the steel vaporized inside damp concrete. 95% of the damage > was caused by the EMP. [ElectoMagnetic Pulse] > I lost the 11 GHz Cars band STL, the 1A2 type phone system, > all the computer terminals, and had some minor problems with > other electronics. It turned out that the dead terminals all had high > ESR electrolytics, [Equivalent Series Resistance - the total of all internal resistances of a capacitor measured in Ohms.] > and that they were working because they were all on UPS [Uninterruptible Power Supply] > before the strike took out all the electricity. The power 1A2 supply > needed some of the weird WE fuses, one KTU card and was back > in service. The STL [Studio-to-Transmitter Link (see http://www.fmamtv.com/rdstl.html)] > was mounted on the tower in a steel NEMA box, and lost the LO [Local Oscillator] > module. It was 20 years old, and at least 10 years obsolete, so it > needed that module updated, anyway. > > I started with the phones, then arranged a twice a day courier form > the studio to the transmitter site with U-matic tapes. We rented a > STL transmitter and shipped the damaged system to the OEM for > repair & upgrading. The terminals were down for a day, while I > waited for the new electrolytics. Or viewers didn't even know we > had been hit. Then I moved the microwave racks to a closet in the > corner of the building, and used 4" EMT [Electrical Metallic Tubing, i.e. metal conduit] > between the rack and the tower. That was 20 years ago. They > have had strikes since then, but no problems. Would you please sum up what you believe to be prudent protection (for electronic equipment) from nearby lightning strikes? I'm thinking of both in single-family homes and in condo/apartment buildings. What would you do to protect from in-house (or in-building) surges, such as elevator motors suddenly shorting out, or welding equipment in use? *TimDaniels*
From: Timothy Daniels on 4 May 2008 13:47 "Tony Hwang" wrote: > You seem to be confused between current flow(energy) and voltage(poential) > Nothing flows in an open circuit. If not we > have to rewrite Ohm's law. Show your credential to make a > stamement like that. You're forgetting RF frequencies - which can flow (back and forth) quite readily in an open circuit such as a transmitter tower, whip antenna, or transmission line, or building power wiring, steel frame, etc. *TimDaniels*
From: Don Kelly on 4 May 2008 22:05
---------------------------- "Tony Hwang" <dragon40(a)shaw.ca> wrote in message news:dncTj.112858$rd2.31639(a)pd7urf3no... > phil-news-nospam(a)ipal.net wrote: >> In alt.tv.tech.hdtv Michael A. Terrell <mike.terrell(a)earthlink.net> >> wrote: >> >> | Bullshit. Like ALL charges, it simply seeks a complete circuit to >> | flow. You have absolutely no grasp of the basic concepts, yet you >> | continue to spout your ignorance and lies. >> >> Not true. >> >> When you close a switch between a power source and a pair of wires that >> go >> out yonder, the electrical energy does not "know" whether the circuit is >> complete or not. If it refused to flow, it would not be able to find >> out. >> It will flow, whether the circuit is complete or not. What happens after >> that depends on what is at the other end, which could be an open >> condition, >> a short circuit, or some kind of resistive or reactive load. >> >> You've claimed to have worked in broadcasting in an engineering role. So >> you should understand what happens at the end of an open transmission >> line. >> The electricity flows to get to the open end. Yet it is not a "complete >> circuit". >> > Hmmm, > You seem to be confused between current flow(energy) and voltage(poential) > Nothing flows in an open circuit. If not we have to rewrite Ohm's law. > Show your credential to make a stamement like that. > Shameful. ------------------------ Actually, you are showing some confusion. Phil is right in that he is bringing out a point that normal lumped RLC circuit theory doesn't handle because it essentially treats the speed of propagation of electrical signals as if it were infinite- which isn't true. 1)Current (not current flow which is meaningless) is NOT energy. Current*voltage*time IS energy- .. 2)Also, on energizing a line whether it is open or closed, there is a current flow as the applied voltage "sees" the characteristic impedance of the line (wire or whatever) so a current will flow-even on an open circuit- until there is a modifying reflection from the termination. For a house the distances are such that this may be of the order of 0.1-0.2 microsecond. After all such reflections at terminations have ceased or are negligable, conventional circuit theory is applicable. In these situations, you are dealing with wave propagation rather than conventional circuit theory. This is the regime that is of interest in considering "surge protectors" As to the advantage of "whole house" vs local surge protection, "whole house protection depends on distances to all "protected" items being small. Local protection doesn't but is simply that- local. The effectiveness of either depends considerably on grounding and other factors. The spate of name calling doesn't do anything of use to anybody. -- Don Kelly dhky(a)shawcross.ca remove the X to answer |