There have been numeroous white papers published by various academics and by engineers at companies looking at developing powerline products that treated the powerline as a communications medium. I have cited many of them many times in c.h.a. over the past few years.
Most of them dismiss the inductance of the wire itself. They mostly felt the inductance of the terminations and the capacitance of various loads were the important factors.
Agreed, but I'm sure there have been at least a few occasions in the past 30 years with all the many millions of X-10 modules in use when an X-10 signal reaching a dimmer (X-10 or otherwise) was at least as high as the average Insteon signal. Why haven't we heard of flicker before this?
FWIW, my ESM1 measurements around my rather large apartment do not show the degree of attenuation you see. Unfortunately, I'm no longer able to do the amount of walking required to repeat the measurements but as best I recall, using a TM751 as the source, I had at least 2-3V at all outlets after adding one filter on my TV/VCR and associated gear.
Most of the reports of Insteon involved dimmers with 300W or more load, dimmed to about 50%, flickering when an Insteon control signal was present on the powerline. That they had to be dimmed to see the flicker would indicate they were turning on prematurely, flashing to full bright for some half cycles.
There were also reports of non-Insteon dimmers flickering under the same circumstances. I believe Bruce Robin reported that he saw the flicker with a non-Insteon dimmer but I do not recall the details.
The inductor in series with the load is there to limit di/dt. It was probably required by the FCC to reduce EMI.
I think this is all starting to make sense. The highest di/dt transition is when there is a heavy load and the conduction angle for the triac is ~4.16 ms in from the zero crossing (50% dim). This high current pulse must have coupled back into a high impedance node (either the zero crossing detector, or the XTAL input pin on the uP). Either way, the altered timing caused abnormal conduction angles which showed up as flicker.
Increasing the value of the inductor attenuates the signal enough to alleviate the symptom.
The wire manufactures also dismiss the inductance, and at first I didn't think it would be a factor either. I pulled in well over 1000 feet for just the lower level, and some of those runs have to be over 100 feet. The specs I found on some Monster cables indicated about .2uH per foot. So, series inductance in the 5 to 25 uH region is reasonable, and that is the range in my simulation. While distributed capacitance of the wire itself can be neglected, devices plugged in cannot. So I have included capacitance at random locations ranging from .01uF to a signal sucking .1uF. It is interesting to note that 25uH and .1uH is resonant at 100KHz. In my frequency sweep test, the longer runs had peaks and nulls at various frequencies.
I don't expect to see flicker at normal X10 signal levels. I just reported this special case in case anyone else observed something similar. The XTB-II is normally connected at the distribution panel. I measured about
20Vpp on those busses. From there almost 40 circuits branch out throughout the house, and I saw 1Vpp to 5Vpp (ESM1 max) on all circuits I tested with the XTB at that location. Except for the "electronics circuit" and one APC UPS, nothing else is isolated with a filter.
I have been working on the XTB-II firmware, and have it temporarily located on a branch circuit in the family room where the Ocelot lives. Because of the inductance between there and the distribution panel, the X10 signal on that branch circuit is much higher than it would normally be, which is inducing the flicker. I never saw any flicker when testing the XTB at this location, but its output is somewhat lower.
This house is just under 5000 sq. ft. on two levels, and 80 ft. end to end. The TW523 was a little marginal covering that area, so that's why I designed the XTB.
CE has EMI standards but US seem non-existent. Consumer tolerance for dimmer and filament hum and buzz may be the controlling factor. Whatever the reason, the snubber circuit is an LRC network even if the inductance is entirely owing to the load and not part of the device as is the case with a built-in choke.
4.16 ms is indeed 50% into the half-cycle, and so is peak voltage, and, assuming the filament is as at constant temperature during any given cycle and thus R ~ constant, is also peak current. But at the peak, di/dt = 0 , not "highest". Or by "di/dt transition" did you mean the second derivative?
(And FWIW, 4.16 ms is about 71% of RMS voltage and 33% of luminous intensity for typical incandescent lamp and not "50% dim" by those measures of dimming.)
Not to dismiss the possibility, but why "must have" ?
This the fix I mentioned that SmartLabs put in place for INSTEON .
The tendency to flicker with increased load could conceivably be caused by decrease in series inductance (and consequent decreased attenuation) with increased current (load). The inductance of non-gapped inductors like the rods and toroid used in dimmers does decrease with current, but I don't know the magnitude of the decrease or whether it is significant with a negligible DC component.
Except for one thing: The flicker continues, and becomes even more noticeable as the lights are dimmed even more. As they ramped down to max dim, they would flash on every time another dim command was sent. But remember, these X10 signal levels are WAY above those expected in a normal configuration.
I think the bottom line is that there is an acceptable signal level window for these PLC devices. Too low, and control becomes marginal. Too high, and dimmers can start to flicker. The Insteon dimmers apparently misbehaved at normal signal levels. I found X10 dimmers can also misbehave when confronted with signal levels several times higher than normal.
And here are several links to other studies. Some may be out of date. At one time there was a list of 40+ such papers that had been given at one or more of the annual conferences. It's given in the second URL but I don't know how many are still good. See pages 4-5 of the ST7537 appnote.
formatting link
formatting link
formatting link
formatting link
formatting link
formatting link
formatting link
formatting link
formatting link
formatting link
formatting link
It is also worth noting that Europe may have hundreds of residences on a transformer.
Because the Insteon dimmer uses a uP, and its frequency is greater than
9kHz, FCC part 15 regulations will have to be met.
For dimming, the triac is abrubtly turned on mid-cycle, so di/dt is high. The triac turns off at the next zero crossing. The uP repeats this process for a set dim level.
Yes, this is the RMS value. But 33% dim as measured by RMS may appear to be brighter to the viewer. Doesn't the eye work more as a peak detector than an RMS detector? Isn't this why multiplexed LED displays appear brighter than they otherwise should?
Okay, maybe my wording was too strong here.
Yes. This is the subject that I was talking about.
A powdered toroid core can have a distributed air-gap.
I was talking to the Insteon module flicker issue in my last post. The XTB-II large output flicker problem could be resolved with a better dV/dt snubber circuit in the module.
I read that section and scanned a few other papers. Nothing I read disagreed with what the simulation showed.
From the Thompson reference: "For typical resistive loads, signal attenuation is expected to be 2 to 40dB at 150KHz".
In both the simulation and measured here, the signals fall off as the distance from the distribution panel increases. I note again that I did not unplug any potential problem loads when I did this testing. I wanted to see how the XTB-II would do driving a typical household distribution system. So there were probably a few signal suckers thrown into the mix. The goal of the XTB is to provide enough signal so it isn't essential to identify and isolate every problem load.
Hmm. Seems like fish-brain still hasn't comprehended how Z-Wave works. The Z-Wave RF signal hops from one node to another SEQUENTIALLY until it has used up its 4 hops. The Z-Wave RF signal is not ubiquitous. It goes from node A to node B, then it goes from node B to node C, then it goes from node C to node D, and then it goes from node D to node E. It cannot go to another node after E as it has used up all its hops. Each sequential hop takes about
60mS or 250mS for A>B>C>D>E. Sending an ACK back from node E to node A takes the same number of hops and time. This is the best case scenario - things deteriorate if there are any problems along the way, like Bobby Green's stealthy spouse blocking a signal sequence.
Lutron's RadioRA has repeaters every 25' which repeat in real-time. That RF signal IS ubiquitous.
The Insteon signal is semi-sequential and has a limited number of hops but it tends to become more ubiquitous as more nodes receive and repeat the signal (simultaneously) but I suspect this is all beyond the comprehension of a tiny fish-brain.
I'm not trying to educate him. I'm merely leading him along very gently by the nose allowing him to expose his cluelessness and nastiness in his own words for all to see. He's been very obliging. ;)
For any PETA members, I always practice "catch and release".
Hopefully, any lurkers will be educated both about Z-Wave and about this rare species of bottom feeding bass.
Hmm. Sounds like Mr. Houston still can't disagree without resorting to childish taunts. Most people stop making fun of other folks' names when they reach middle school.
[sigh] Let me try to explain this in simpler terms. Imagine for a moment that Mr Houston's suggestion (made without benefit of ever having seen, let alone tested Z-Wave) that this system can only travel 25 feet per hop. If the controller is in the middle of the home that's 100 feet in each direction. You now have a maximum coverage of
200' in any direction.
Houston's idea that 217 additional nodes would all be unable to reach the controller assumes that al;l of them would be placed beyond the 4-hop limit. This would be true if they were all installed in a line. Perhaps Mr Houston is accustomed to homes that are ver-r-r-r-ry long and narrow. :^)
Mr Houston is trying to force an erroneous conclusion by assuming that all nodes in a system are located in a straight line, separated at 30' intervals. The typical installation has nodes scattered throughout the home, each taking whatever is the optimum rout from its location.
Actually, it is a for all intents and purposes a non-existant worst case scenario based on a layout that would almost never exist in a real world app. I suspect Mr Houston knows this but he's so hell-bent on villifying Z-Wave that he insists it is normal.
Radio RA's repeaters repeat the signal after they receive it, just as all receivers do. Nothing is truly instantaneous.
Interestingly, the makers of Insteon came out with this after Z-Wave did the exact same thing. The difference is Insteon suffers from lots of problems which have been enumerated here and on various message boards. Z-Wave is more robust than Insteon, has better support (well, if we don't count Dave Houston) and is more likely to still exist
10 years from now.
Schoolyard insults stop bothering most people me around age 13. Come to think of it, most people stop making schoolyard insults at about age 13.
I can't. I need it every time Mr. Houston posts. :^)
Some confusion here. We were talking about different devices. I was responding to Jeff's post which involved x-10 lamp modules from various eras. I doubt that early x-10 modules (pre-1991) met current FCC part 15. You were referring to INSTEON where it does pertain.
Right. I think I understand what you mean now, namely, that the _longest_ period of _time_ from ON to 0 volts occurs at Vpeak = Ipeak = 4.16 ms past zero-xing. I was referring to the fact that di/dt during turn on -- the derivative, 'instantaneous' -- is similar regardless of what part of the cycle (delay in ms) the TRIAC turns on. And it is the slew rate which is the instantaneous change in voltage wrt t and so is dv/dt. (leastwise that's how I've construed for years ;-)
brighter to the viewer. Doesn't the eye work more as a peak detector >than an RMS detector? Isn't this why multiplexed LED displays appear >brighter than they otherwise should?
"Luminous intensity" is physical property and is not measured with respect to human perception. The cited 33% (of the undimmed output) is a calculated value based on typical incandescent lamp properties. See my spreadsheet at
formatting link
for relevant equations, tables and graphs.
[snip]
And I was coming _back_ to the topic you were already on -- we were out of phase as it were ;-)
Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.