BPL (Broadband over Power Lines)

[paulengr 44]

Anyone have any experience doing this? Details of the specific scenario: I work for a large mine in the U.S. (roughly 7 miles long by about the same width). Our power comes in at 230 kV, stepped down to 23 kV, and then dsitributed over open ACSR from there. At point of use, we usually step down to 4160 or 2300, rarely going directly to 480 V because of the large frame motors that are in common use at the point of use. The area that it is in is flat as a pancake except for the "canyons" that we build ourselves. We do about 60% of our power generation ourselves (cogen). All of the equipment including substations is mobile and constantly gets rearranged as the mine advances. Trying to run a wired network in the mine is traditionally futile. About 20 years ago they went down the wireless route. Needless to say this by itself is slowly becoming more and more difficult to maintain as the mine grows ever larger. Granted there's technically no difference between running power lines and communication lines but for whatever reason, the mine production folks will destroy control power without hesitation compared to power distribution lines. Probably has something to do with the fact that one causes downtime and the other can also kill you. I've used powerline communication before. Years ago, I handled a college radio station (FM carrier current box). My house still has powerline modems in it to eliminate the wiring and hassle of trying to find a decent wireless bridge back to the wireless router from fixed equipment (TV, game machines). And I've used the pilot carrier utility stuff on occasion. I'm aware of the big "ARRL vs. everyone else" fight. The ARRL hasn't made a technically solid case (and I've run into far too many HAM operators myself that were bleeding all over an adjacent site and claiming that they were "within FCC rules" despite running such high power that they blasted their way through a 10.7 MHz crystal IF filter with harmonics from their transmitters). Fortunately because of geography the site is so isolated that from a practical point of view we don't have to deal with this. I'm also aware that the way the FCC rules are currently written, you sort of have to be a "utility" though I'm not sure if the site qualifies. Regardless because of geography, the site won't have a chance of causing interference in the first place. I've done some searching and it's hard to find manufacturers/distributers because it seems like everyone is scurrying for cover from the ARRL and similar law suit nazis. Does anyone have experience with this stuff? Any information where I can pursue looking at whether it's a viable option.

[BobB 58]

My only experience with this stuff was at an air force base in Ozz. 415V generation, step up to 22kV, undergroiund cables so capacitance was high and power factor leading, generators do not generally like leading power factor and so there was an inductive load bank to pull the power factor down - half worked. The powerline switching system signal was injected into the 415V and then stepped up to 22kV. At the other end there was a step down transfomer to 415V and the receivers were connected to this. Worked properly for a short time and then started to cause trouble - sometimes worked - did not work. Lightning strike and blew most of it up and had to be replaced - also blew up all the surge protection, control cables and most comms things around the base. I guess I could not recommend it based on my only experience but this may have been an isolated case and may have had something to do with the brand we had to use - I do not know. I hope you do not mind warts and all. Good luck and talk to your suppliers - throw this one at them if you like - and make sure you get all their assurances (there will probably be plenty) in writing so you can kick them later if you have problems. Good luck and investigate properly.