Cars can be either way. My brother's 1941 Plymouth is nominally positive to chassis (and 6V). Actually it does not care. Lights and field-coil motors work either way. Older batteries could be charged either way. Sometimes a car would become reversed after a careless jump-start. The sparks work slightly better one way (I think so electrons jump off the hot side-electrode?); there is a trick with a graphite pencil to check this. System polarity can actually be uncertain until you "flash the generator": set strong residual magnetism in the core so it comes up the same polarity every time.
There is a theory about galvanic corrosion being less-bad one way than the other but I forget how that goes.
OK, but positive grounded cars almost dissapeared in the earth.
I knew that telephone systems were 48V positive ground because of corrosion in lead protected underground cables. I don't know if it actually keeps the same as wire telephones also are extinguishing (an error imo).
I knew that telephone systems were 48V positive ground because of corrosion in lead protected underground cables. I don't know if it actually keeps the same as wire telephones also are extinguishing (an error imo).
That's it!! IIRC the thought was carried into electric trains and into automobiles.
Brother's driveway showing one positive-ground car still above the earth.
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my brother in law was working in his garage during a lightning storm. he touched something, i think pipe, and felt a jolt of electricity. The emergency room confirmed it by the damaged it caused his heart, among other organs. he got lucky obviously, it wasnt the full force of a lightning bolt. but he had to see a cardiologist every few months.
so the pipe wasn't grounded or done properly. my guess is that the lightning struck something nearby, the electricity flowed through the ground to the pipe, and found a lower potential touching his body to complete the circuit. Calling "ground" or "earth" 0V is just a convenient convention. it's the potential difference between 2 points that matter or even mean anything.
after many years, he's fine now.
Well, if we are telling lightning stories ... when I was a kid, lightning blew up the neighbor's toilet bowl. Apparently it hit the out in the yard and ran up the pipes (I didn't see that part, just helped fix the bathroom). I always thought it was the well/pump, but apparently it was more likely the septic/drain field.
I had received almost two times, not directly a bolt, but some of the spayed energy; through the power line. One blow the SMPS of one of my 486's PC only damaging the diode bridge and the fuse. The other inside the volume control in a Regen between the switch contact and the box of the pot. The damage were not so serious because the differential switch opened the line immediately. In a third event didn't actually destroyed nothing but reseted the wearher station although it is energized from my 12V system from solar energy completely isolated from line.
IMO the problem with storm discharges, isn't the resistance, is the inductance ofereded by lightning bolts and its wires to Earth. As a bolt is a quasi Dirac Delta function (tremendous energy discharge in few milliseconds), the voltage drop in its inductances are giants. So no matter how good a grounded can be done, it will requiere low inductance wiring, not always possible in larger buildings.
IMO the problem with storm discharges, isn't the resistance, is the inductance ofereded by lightning bolts and its wires to Earth. As a bolt is a quasi Dirac Delta function (tremendous energy discharge in few milliseconds), the voltage drop in its inductances are giants. So no matter how good a grounded can be done, it will requiere low inductance wiring, not always possible in larger buildings.
Most solar gear is available in either pos or neg ground, but it has to be consistant throughout the entire circuit. All components need to be either pos or neg ground even if its isolated. I think if its just the panels that dont match this can be achieved simply by relabeling the pos and neg on the panels, but not recommended due to potential confusion scenarios.
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i am trying to build a music recording setup, including electric guitar, on an isolated floating solar circuit, are you suggesting that an inverter with grid tie capabilities (but not tied in to grid) would be more compatible in such a system?
No need for inverter, use DC from a battery...most equipment steps it down and back to DC anyway.
Charge battery from solar panels.
Less interference issues.
Charge battery from solar panels.
Less interference issues.
Positive ground in telecom is (still common!) because the + attracts the dust an dirt so not the equipment but the rack/casings/frames/cabinets will attract the dust.
So your saying use buck/boosts on everything instead? Getting a seperate DC buck/boost converter for each piece of gear and finding where to bypass the internal 120v conversion i'd probably want to switch it so it could go either way DC or AC. Thats a lot of work so if an inverter designed for grid tie in (even tho. I dont plan to use it that way) would also provide a solution it would also have other benefits. Mainly just interested in what was said about grid tie inverters having reverse flow capabilities.
Build or find amps that use what is available as DC from the solar panels, that is what my meaning was.
Buck / boost are high frequency switchers, not fully efficient, and are noisy at times.
Buck / boost are high frequency switchers, not fully efficient, and are noisy at times.