BigDaddyI thought surge suppressors "burned out" with surges. Am I wrong?
In practice, as noted the 'surge suppression' in the cheap devices is done with a single MOV, likely physically resembling a large disc capacitor. This is connected as a 'short' between the hot and neutral, or from a protected line to ground, and it works by promptly dropping resistance when subjected to overvoltage. Since many forms of spike that are lethal to tiny semiconductor architecture are of relatively short duration, the 'short' to any part of the AC waveform potential during the time the MOV is conducting is relatively brief also; when the voltage comes down, the MOV goes back to high resistance, and all is well.
The problem comes in when the surge has current as well as voltage behind it, like a nearby lightning strike (or some types of EMP). Now when the MOV conducts, a high transient current goes through it ... and while the resistance is small compared with impedance of the connected equipment, it is still large enough for P=I2R to rise up and bite. This likely causes permanent cumulative damage to a MOV even if it does not fail. I would frequently find the two sides of the 'disc' of a MOV completely blown off in a failure -- little matter to fix; you unsolder the legs and solder in a replacement. But until you do, the protection is, well, at a permanent very high resistance and no longer effective at surge suppression... and you may not have any warning the "protection" has not failed safe. [As a note: you can design surge protectors to 'fail safe' but this involves them ceasing to provide power to their outlet(s) permanently, without warning, and many consumers rise up in rage at discovering their $20 or more power strip is suddenly and forever 'no good'...]
A better class of surge protection would use something like Zener diodes, or some variety of gas tube, that conducts large currents to effective ground within a few nanoseconds of overvoltage rise time. And then just as quickly shuts off when the overvoltage goes back down. It is possible to design these to survive larger peak voltages and currents without potential (no pun intended) damage to connected equipment. In some cases it is necessary to provide 'charge storage' for the electrons transferred in a pulse event, where it is impossible to 'dump' them to an external conductor or ground that has a lower potential; this can be difficult to arrange in the necessary short time imposed by, say, electron-displacement EMP.
Nothing will save you if the strke is on or near your house - even unplugged stuff can be damaged in that case. But cheap surge supressors can be worse than none - if only because they give a false sense of security.
The MOVs do degrade over tiem depending on the level of surge they see. Even if you never get a big enough hit to destroy it outright, they do degrade over time. The better ones will tell you to replace them every so many years, even if you've never taken a major hit. Some do have circuitry to induicate the effectiveness of the protection, or at least indicate that the protection has fallen below the rated value and it's time to get a new one.
For my test gear, I have a surge porotector and filter, not only does it have surge protection across all legs, it also has EMI filters to keep electrical noise out of the plugged in equipment. Overkill? Maybe, but they aren't any more expensive than a good quality surge protector, plus these have a remote on/off switch which I mounted in the corner of the bench so it is easily reachable while the base with the outlets sits in the back.
I had one of these for my layout 2 layouts ago, put the switch ina convenient position and mounted the base up under the benchwork - single switch (which has a pilot light in it) turned the whole layout on and off.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
New surge protector ordered this morning: Tripp-Lite Isobar Ultrablok. I have been using one of these for my music studio gear for several years with satisfactory results.
Started using the multimeter to do continuity testing. I ran tests on all the freight cars that were on the layout at the time of the incident and all of them checked out ok, no short circuiting of the metal wheelsets. Progress....
The PowerCab is finally on it's way back to NCE. The USPS screwed up and picked up the package two days late. Sigh...
Bill
"Never try to teach a pig to sing. It wastes your time and annoys the pig"
alfadawg01 The PowerCab is finally on it's way back to NCE. The USPS screwed up and picked up the package two days late. Sigh...
Rich
Alton Junction
richhotrain alfadawg01 The PowerCab is finally on it's way back to NCE. The USPS screwed up and picked up the package two days late. Sigh... Nah, no screw up, that is standard USPS procedure. Rich
Nah, no screw up, that is standard USPS procedure.
Of course.....the new normal. Silly me, why didn't I think of that?
I have conducted the first phase of testing by setting the multimeter to test conductivity and running it over every inch of track on the layout, all 24' or so of it. The buzzer was quiet so it appears there are no short circuits.
One question however. When I touch both probes to the same rail, the buzzer sounds, as expected. However, when I touch the probes to the same rail with an insulated rail joiner between the probes, the buzzer still sounds. Is that supposed to happen?
Bill,
What is your trackwork insulated from at that spot? Are you running feeders to both sections of track from a power bus? If it is insulated then you should NOT be seeing continuity between the two sections of rail.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
edit-delete if I didn't open my mouth so much, I would think I was a lot smarter.
Henry
COB Potomac & Northern
Shenandoah Valley
alfadawg01when I touch the probes to the same rail with an insulated rail joiner between the probes, the buzzer still sounds. Is that supposed to happen?
The immediate thing I'd do is to switch to the ohm setting and make the same measurement. If the meter shows the equivalent of a short (like an L or -1 depending on meter type) then your "insulated" rail joiner may not be working as designed... if the number of ohms is finite, the joiner may be compromised in some way. Report the number you get when you measure.
alfadawg01However, when I touch the probes to the same rail with an insulated rail joiner between the probes, the buzzer still sounds.
why is the insulated rail joiner there? what is it's purpose?
is there another gap on that rail?
greg - Philadelphia & Reading / Reading
I have insulated joiners at the frog ends of my turnouts on each rail of the through route and the diverging route. There are feeders near the point end of the turnout and beyond the insulated joiner. Is that easy to visualize? I can provide a sketch if it helps.
I set the meter for ohms and set the probes on either side of the joiner. Reading was 0.
Turnouts are code 100 Peco Insulfrog.
This wiring diagram may help:
You need to use a photo hosting service to post pics - on the main forum there is a sticky with instructions.
If there is a feeder to the rails from a bus, then an insulated joiner, then another feeder fromt he same bus, all on the same rail - you will get contnuity across the gap, because both sides are linked by the wire. That's not necessarily a problem, and Insulfrogs don;t really need gaps or insulated joiners on the frog rails anyway. Electrofrogs do, if there are any feeders past the frog (which there will be on all but the most trivial of track arrangements).
Randy,
So the way I've wired things, while probably being a bit of overkill, is not a problem?
Didn't notice the OP used google photos because I could see it. I don't always see google photos, but that is another discussion. I pirated his photo
Thanks, Henry, whatever works.
It's better to ask for forgiveness than permission And don't all great stories involve pirates?
I see someone else watches The History Guy
rrinker I see someone else watches The History Guy
Who?
alfadawg01Does anyone see any problems with the wiring plan?
it explains the above.
alfadawg01This was a functioning layout with a DC power pack. I wired track power from the DC power pack and the PowerCab through a DPDT center-off toggle switch so I could use either one (but not both simultaneously!) to power the layout.
i still don't understand what damaged the PowerCab. i would suggest disconnecting the DC controller from the layout when connecting the PowerCab.
could you post a diagram of how the DPDT switch is wired to the DC PowerPack, PowerCab and layout
Here's a sketch of the wiring at the base of the DPDT center-off switch.
for the click impaired
Removed at OP's request.
Overmod I protest the unnecessary political slant of that drawing as provided, particularly the kokkinoerythrophobia implied by its orientation. Surely we are above preferring one color over another in our modern societal preferences! Simply rotating the drawing 90 degrees would address the implied privilege issue... although then the primacy of Western-centric reading/scanning preference comes into play. Perhaps using non-politically-charged wire descriptions, like 'hot' and 'ground' (terms chosen themselves to remove the taint associated with terms like 'positive' or 'negative' and their potentially-racist color implications) should have been used.
I protest the unnecessary political slant of that drawing as provided, particularly the kokkinoerythrophobia implied by its orientation. Surely we are above preferring one color over another in our modern societal preferences!
Simply rotating the drawing 90 degrees would address the implied privilege issue... although then the primacy of Western-centric reading/scanning preference comes into play.
Perhaps using non-politically-charged wire descriptions, like 'hot' and 'ground' (terms chosen themselves to remove the taint associated with terms like 'positive' or 'negative' and their potentially-racist color implications) should have been used.
Well, if it is to be assessed as such, I do sympathize a bit with our friend Overmod. Truth is, I pulled a similar stunt on another forum two months ago with largely the same theme, and I was immediately, and firmly, spanked by the administrator. Chastened, I apologized for my hubris, and have sat on my hands ever since.
We are bombarded by political correctness, and it gets to all of us at times. Overmod gets a pass from me for a joke that perhaps needed a better foil to b funny.
Seems like this thread has exceeded it's shelf life. I will entertain useful comments if there are any left to be made, otherwise I will make the upgrades to my layout that i've planned on and await NCE's repairs to my PowerCab. Thanks to all who have provided valuable suggestions and insights, I know more now than when I started.
I see no reason for alfadawg01 to get piled on. After all, it is his thread. So, I will side with him. The offensive post can easily be deleted by either its author or the moderator.
I have often thought that it would be a good addition to the software to give an OP the ability to delete posts from his own thread for whatever the reason.
alfadawg01Seems like this thread has exceeded it's shelf life.
Hijacking of threads happens in every forum on the Internet. Don't leave us without a final answer to your problems.
I started a thread that veered to hockey, hockey pucks, people wanting to give me hockey pucks. I don't remember what even the thread was about, but I know a lot about hockey pucks now.
I didn't see anything wrong with his wiring, but I already had one response that was wrong and I deleted.