Adam,Yes, I agree. Any kind of outdoor electrical equipment that the power company utilizes that is designed to be subjected to literally decades of round-the-clock operation and abuse in some of the harshest of ambient conditions absolutely must be very robustly built, as opposed to the 'most economical' construction that is typically utilized for the components of most consumer end products.
David----- Original Message ----- From: "Yurtle Turtle via Tesla" <tesla@xxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx> Sent: Monday, April 23, 2018 3:17 PM Subject: Re: [TCML] Finally Fired off Green Monster With New Caps.
And don't forget, we live in the South. Pigs were designed to work in Death Valley, where AC runs wide open when it's hottest, with a HUGE factor of safety. After all, they ain't cheap for the power company to replace by scimpimg on construction.Adam - 25 kVA 14.4 kV pig, built in the 70s.On Sunday, April 22, 2018, 5:43:21 PM EDT, David Rieben <drieben@xxxxxxx> wrote:Steve, Well, I wouldn't go as far as to say completely "abandon" my Maxwells(catalog # 31885). Heck, I have four of them that I picked years ago on oneof those real eBay deals. Of course the Maxwell units are of the white PVC containment system, with the both terminals on the same end, and with theinsulator barrier between the terminals. The GE caps, at about 33 lbs. each, are of the welded metal can containment, with a single standoff bushing for one terminal and the external case itself as the other terminal. I see thatBert Hickman has already sent you a link to some of the spaecs of these GE caps, although I do not see any of the more detailed spec ratings that youwere likely thinking of (peak and RMS current rating, dV/dT derivative, and such), as this may be proprietary info. Since these caps are indeed desinged to be placed continuously across 13.8 kVAC and can be operated at up to 15.2kVAC, they must obviously be designed for 100% V-reversals, at least at 60 hz. I do know that these caps do encorporate the PP "hazy film" dielectric system as well as extended endfoil connections, and are also designed mechanically very robust. They are so well packed internally that I cannot detect ANY oil 'slosh' sound while moving them about. Your adjusatable air gap spacing of your inductive ballast for current control is a really neat idea. I simply adjusted my original air gap for aspacing that allowed me to draw about 100 amps from the 240 volt mains when seriesed with a dead short, then fixed the gap permanently at this setting.I simply use the main power control variac to vary the voltage at a fixed inductive ballast.You've really done well to keep all electronic interferance out of your homewhile running you coil, although operating 75 ft. away in a seperate shop building is probably helpful in this aspect, too. Since I have to store mybig coil inside of my attached two-car garage and, due to vertical clearanceissues, "decapitate" its topload donut to roll it out from underneath the overhead door and then reassemble once outside, and run it outside (and reverse the process to put it back inside), I am not as blessed with operational space as you (and I am at the mercy of whatever Mother Nature has in mind as to whether or nor I can operate it). I have driven three interconnected grounding rods inconspicuously next to my driveway and thecentral grounding rod only allows about 35 ft. distance from ground zero tomy home structure. Unfortunately, the wife still complains about the TVscreen going completely black while I am firing my coil (we have a satellite dish as opposed to cable) and one of the florescent lights in my shop shuts down while the sparks are spewing. Fortunately, the ill-effects immediatelydisappear and everything seems to return to normal once the coil is shut down. Since I reside in a suburban environment on a mere 1/3 acre lot and surrounded by neighbors, a seperate shop pole barn is still a future dreamfor me, once we can relocate to and build on our 40 acres of open property.Yes, I have also employed just about every conceivable filtering device thatcan be assembled for coil operation. MOVs on both the LV input and the HV output (distribution arresters), and multiple EMI line filters. Seems like sufficient distance (and possibly Faraday shielding by operation inside a metal pole barn building) is still the operative word for keeping the generated interferance to sensitive electronics to a minimum. Although I'm sure that some others may disagree with me, I personally feel that 'Terry filters' are really not really necessary for protection of non-current limited power transformers, especially those that are designed for the extreme rigors of line transients caused by switching surges and lightning strikes in a 24/7 exposure to the iutdoor elements (pole pigs or PTs designed for outdoor operation). The Terry filter was originally designed to address the issue of run-away resonance when inexperienced coilers ran their coils with a primary C that was near resonance with themains frequency, while opening their stationary gaps ever wider and wider to get longer sparks when powered by the very fragile, current limited NSTs or OBITs. Since pole pigs are electrically (and mechanically) MUCH MORE robustin relation to their voltage/current ratings, and since most coils of this magnitude are driven by a high break rate rotary gap when ASYNC, and the primary cap is usually considerably smaller than resonant (STR) with the mains frequency, I feel that this level of 'protection' is reallyunnecessary in this situation. To me, at least, it's kind of like building a picket fence to protect a stone wall. ;^) Of course, it certainly can't hurt and if it gives you more 'peace of mind', then by all means, go for it. I do utilize properly rated distribution arreser MOVs that the power company used on their primary diostribution lines for some level of protection on the HVside of my coil as well, though, although I did not always do it and still never had a pole pig die in Tesla coil duty. David----- Original Message ----- From: "Steve White" <steve.white1@xxxxxxxxx>To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx> Sent: Saturday, April 21, 2018 10:24 PM Subject: Re: [TCML] Finally Fired off Green Monster With New Caps.Just curious. Are you abandoning the Maxwell for the GEs or was this just an experiment to see how the GE caps work? Do you have a data sheet for the GE caps? If so I would like to take a look. My pole pig powered coil uses a bank of 6 Maxwells in a series-parallel configuration to get 45 nF of capacitance at a 70 KV rating. It also has an adjustable air gap ballast that I built. I am not using any resistive ballast, although like you, I have wondered if I should be using some. Also, like you, I can't stand the thought of wasting precious power as heat. That is why I built the adjustable air gap ballast in the first place! I currently have it set for 20 amps although I designed it tohandle up to 50 amps. My control cabinet is closed so I can't see if there are any unwanted sparks anywhere. Maybe I should look in the back while itis operating. I do have numerous protective features such as line filtersand big MOVs in the cabinet. I haven't noticed any ill effects on anythingin my house. I have seen my wife watching TV while the coil was in operation. The computers in the house are also on during operation. I do turn all electronics off in my workshop before opera tion. My workshop, where I operate the coil, is about 75 feet away from the house and I imagine that I may be getting some kind of additional filtering effect from the 75 feet of buried power line between the house and workshop.I am currently in the process of adding a low pass filter ("Terry" filter)to the HV output of my pole pig for some additional protection for it. I deleted the MOVs. Steve ----- Original Message ----- From: "David Rieben" <drieben@xxxxxxx> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx> Sent: Saturday, April 21, 2018 9:31:22 PM Subject: [TCML] Finally Fired off Green Monster With New Caps. Some of you may remeber that I posted to the list an enquiry about the suitability of GE protective power caps (2X 0.25 uFd @ 13.8 kVAC in series) for Tesla coil operation, probably several months ago now. Bert Hickman thought that they would be quite suitable for Tesla coil duty, so that was good enough for me to give 'em a try. ;^) Well, between being back to working 40 hours a week and what seems like a life time of miserable, rainy weekends, I finally got a good day to try out those caps in my coil. Since I was replacing a 0.1 uFd Maxwell pulse cap (measured Cabout 0.114 uFd) with a measured C of 0.135 uFd, the coil obviously needed retuning for optimal operation. Since I am forced to run it outdoors in mydriveway and the primary tap takes several minutes to loosen and reattach each time I change it, I was really only able to get a preliminary tuning down to the nearest whole turn, but still good enough for a test run. I have also added 0.33 ohms worth of power resistors on one of the 'hot'240 volt input legs, in combination with my inductive ballast on the other'hot' input to my pole pig since the last time I fired it (probably at least a year by now!) I was trying to further 'smooth' the operation of the coil and further suppress any nasty kickbacks that may find their way back to my control panel or even my home's wiring. Well, she did run fairly well, although it seemed like the added resistance throttled it back a bit. I noticed that even with the variacwheel turned up to around 80, the coil was still only drawing around 60 to65 amps and it seemd that this was about the 'limit' - (it was drawing around 85 to 90 amps before without the added resistive ballasting and with the original 0.1 uFd Maxwell cap with the variac wheel at this samesetting). Of course, even with only 0.33 ohms of added resistance, per theI2R law of joule heating, at 65 amps, thats still about 1400 watts of wasted energy that does NOT make it to those beautiful streamers! Also, there seemed to be more 'wah-wah' beating of the output with my typical 300 to 350 bps roary gap setting - (noticed this more from observing my panel ammeter flactuate than from the actual tone of the sparks). Never-the-less, the output (and current draw) was definitelysmoother and more steady with my original setup. I tried varying the speed of the rotary gap drive to see if I could get out of the beat fluctuationsand find a 'sweet spot', but that didn't really seem to make much difference. So it seems that the added resistance gave me the opposite affect than the 'smoothing' that I was looking for. Anywho, I will probably have an audience next time I run it and the firstthing that I will likely do is try bypassing those power resistors. I havenever really liked the idea of resistive ballasting wasting power in heatanyway, but I have read that a small resistive component in the ballastingdoes tend to smooth out and knock the tops off of some of the nasty kickback transients. I have still occasionally observed an occasional spark inside my control panel where you DON'T want to see sparks! That's the only reason that I was trying the resistive ballasting approach. Those GE protective capacitors DO seem VERY robust, though and never evenbroke a sweat - can you say 27,600 volts AC rating with never more than 17kVAC input??!! (plus they have internal bleeder resistors, making them safer than the typical pulse cap) so at least for now, I'm leaning more toward staying with them and working out the few preliminary kinks that I am having with their operation than changing back to my original 0.1 uFd, 75 kV Maxwell pulse cap.Any comments or suggestions from any of the resident geniuses and/or otherexperienced pole piggy coilers? David _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxxxxxx https://www.pupman.com/mailman/listinfo/tesla _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxxxxxx https://www.pupman.com/mailman/listinfo/tesla_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxxxxxx https://www.pupman.com/mailman/listinfo/tesla _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxxxxxx https://www.pupman.com/mailman/listinfo/tesla
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