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Author Topic: Power line communication anyone?  (Read 8911 times)

Offline Geezer

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Power line communication anyone?
« Reply #25 on: 14/10/2011 17:47:21 »
If the poles are all "line of sight", could you use IR communication (although it can be influenced by weather).
 

Offline Soul Surfer

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Power line communication anyone?
« Reply #26 on: 14/10/2011 18:35:47 »
Almost human.  For a one off  there are probably lots of basic digital communication chips that can be used to implement your system as you suggest simple microcontrollers or PGA can be used to do the logic.  Any single cable has a reasonable characteristic impedence and a simple capacitance resistance circuit can be used to isolate the high voltage and protect the input.  you might need a slightly more poweful driver than a simple communications line but they are available.

When I did the mainsborne telecontrol project we had only just started to use the simplest microprocessors. and the range of chips was very limited an mostly basic logic so you had to design most of it yourself!
« Last Edit: 14/10/2011 18:39:34 by Soul Surfer »
 

Offline CliffordK

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Power line communication anyone?
« Reply #27 on: 14/10/2011 19:11:09 »
At this point the networking would be nice.  However, I think I would avoid the temptation to do networking to every individual lamp.

If several lamps are wired together, then just treat the cluster as a single lamp, and design a dimming approach that can turn the string on and off, as well as dim them.  The Cold Cathode Compact Florescent Lamps are low power, and dimmable, so you would just set the desired voltage at the source.  I know the street lamps are bright...  can the CCFL lamps put out enough light on high power?  Mercury might be an issue, but the lamps should be able to be recycled, especially if you have a lot of them.

It is a bit confusing, but there are both PLC (programmable logic controllers), and PIC Controllers which are essentially a PLC on a single chip.  You should be able to program a PIC to run independently based on the specified algorithm.  It would take the inputs from a photo sensor to determine dawn and dusk.  I would calculate noon and midnight based on halfway between dawn and dusk (good enough for the purposes of the system) to prevent time-drift.  Then program each controller with the desired schedule for the individual lamp.  If necessary, it should be able to guess within a week of the date based on the length of day.

Maintenance would have to be done at each lamp, or each PIC.  However, it should have relatively lower power requirements, and would be unaffected by systemic issues.  Did someone suggest that Fog & rain would interrupt IR?  Is it possible to at least mount your control box at ground level?  Anyway, if you create a good algorithm, then systemic upgrades should be rare.  Keep in mind that with a networking approach, there are still needs for the initial installs, and periodic network repairs and upgrades.
« Last Edit: 14/10/2011 19:15:56 by CliffordK »
 

Offline SeanB

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Power line communication anyone?
« Reply #28 on: 14/10/2011 20:31:30 »
The dimming photocell has already been invented, and is quite common in Switzerland AFAIK, where you find a lot of fixtures that have 2 lamps, one high power and one low power. Both lamps are switched on at sunset, and at midnight the high power one is switched off, only coming on 2 hours before sunrise. The low power lamp is on all night. Generally implemented as a mercury lamp and a LPS lamp, as both have the distinct advantage of a lifetime measured in decades ( not like the current lighting that might make 5 years at best, more like 2 in most cases) and giving a good quality light when people are around ( MV lighted) and a lot of light the rest of the time ( LPS is really efficient at making light, though it is red) when there are not many people around. Otherwise 2 HPS lamps of different power in more recent installations.

They compensate for day length, and set themselves up automatically to switch at midnight.

Dimming is really only going to be feasable if you have high power LED lamp units, and you can integrate the controller into the power supply for the unit, along with the power line interface. Do not forget to make the power supply capable of surviving 5 years at 125C, and to be able to survive multiple simulated lightning spikes applied to the power supply terminals, along with being able to survive prolonged overvoltage ( at least capable to survive lost neutral on a 3 phase system without blowing up or popping a fuse) along with reliable startup at any point from -55 to 125C and any input voltage in the range at the same time. Self resetting thermal protection would also be good.

MV lamps are dimmable, simply by using a multitap ballast and dropping the current of the lit lamp to a lower level. Not going to give a big dimming range, but will offer savings without causing problems for the lamp in terms of life and poor operation. Most sodium and metal halide lamps are not dimmable, unless you use an electronic ballast to run them, and these are not going to survive in street lamp use.
 

Offline Geezer

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Power line communication anyone?
« Reply #29 on: 14/10/2011 20:39:42 »
....and LED lights might not be such a good idea as someone is likely to purloin them :D
 

Offline CliffordK

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Power line communication anyone?
« Reply #30 on: 14/10/2011 22:39:51 »
I did look up LED street lights, and found some 100% LED street light bulbs, as well as complete lamp units with lower overall power consumption than the low-light versions of the standard bulbs.  Since the LEDs use multiple bulbs, it should be easy to shut off 50% or more to run at half power.
 

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Power line communication anyone?
« Reply #30 on: 14/10/2011 22:39:51 »

 

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