Enhanced Summon coming (Elon tweet 6 Apr, 2019)

[dgatwood]

Ummmm DC has a VERY high loss rate per foot which is why your cables are so thick. Want to rewire your house in 8 gauge wire? This is why we use AC.

That’s not really true. DC cables are usually thick because DC is typically used at higher current and lower voltage, and loss depends on amperage (current), not wattage (amps x volts).

We use AC because prior to about thirty years ago, it wasn’t practical to do large-scale, high-power buck/boost conversions to change DC from one voltage to another, whereas AC can be stepped up and down with only transformers. And when running a lot of power (wattage) over a long distance, higher voltage with lower current gives you much, much lower losses, but it isn’t practical to use higher voltages in your home, so voltage conversion is unavoidable.

But HVDC has lower losses than AC, at least when run over superconducting cables. So lately, a lot of distribution is DC, too, now that switched-mode conversion has gotten cheap enough.

 

[DrDabbles]

But HVDC has lower losses than AC, at least when run over superconducting cables. So lately, a lot of distribution is DC, too, now that switched-mode conversion has gotten cheap enough.

HVDC links are lower loss compared to AC links always, not just when using superconductive cables (which are crazy rare). But I only know of HVDC facilities being used as large transmission trunks, where it's then converted to AC for distribution. The reason transmission lines and normal wire for DC is smaller gauge than AC is that AC tends to only use the surface of a conductor whereas DC uses the entire conductor.

The problem is that HVDC conversion is SUUUUUUUPER expensive. DC transmission attempts to recoup these costs by using smaller gauge wire and a reduced conductor count. But this only works when distances are extremely long and conductor material is expensive. Also, conversion has become cheaper but not nearly "cheap enough" and it's very failure prone. There are countless conditions that cause converter facilities and circuit breakers to fail catastrophically. And I mean catastrophically. The low availability of components to repair these systems usually means longer down times and higher repair costs, so using HVDC for anything except tying multiple grids together without needing to sync them all is somewhat unheard of these days.

 

[ebmcs03]

Is enhanced summons here yet?

 

[diplomat33]

Is enhanced summons here yet?

No. Relax, you'll know when it is out.

 

[notAnExpert]

Is enhanced summons here yet?

Yes, but only for those who spell it right.

 

[TT97]

Is enhanced summons here yet?

Can you please stay on topic about AC vs DC. Thank you.

 

[Daniel in SD]

Ummmm DC has a VERY high loss rate per foot which is why your cables are so thick. Want to rewire your house in 8 gauge wire? This is why we use AC.

Pacific DC Intertie - Wikipedia
DC is actually superior for long distance transmission because it only requires 2 wires instead of 3 and has no skin effect (limit to how much of a conductor can conduct current as a function of frequency).
However to convert between DC voltages requires conversion to AC and then back to DC whereas AC voltage conversion only requires a simple transformer. I have no idea if we were designing the power grid from scratch today if it would be DC or AC.
Arguably all electric motors are AC since even "DC" motors require switching current (either from brushes or a motor controller). Tesla drivetrains all have motor controllers that generate AC. All Teslas except RWD Model 3 use an AC motor design invented by Nikola Tesla himself!

 

[JulienW]

Pacific DC Intertie - Wikipedia
DC is actually superior for long distance transmission because it only requires 2 wires instead of 3 and has no skin effect (limit to how much of a conductor can conduct current as a function of frequency).
However to convert between DC voltages requires conversion to AC and then back to DC whereas AC voltage conversion only requires a simple transformer. I have no idea if we were designing the power grid from scratch today if it would be DC or AC.
Arguably all electric motors are AC since even "DC" motors require switching current (either from brushes or a motor controller). Tesla drivetrains all have motor controllers that generate AC. All Teslas except RWD Model 3 use an AC motor design invented by Nikola Tesla himself!

It would still be AC because of all the steps up and down in voltage. Here is the process and no way to invert/rectify that many times.

• At 11 kV or more than that up to 25 kV voltage level is maintained at alternator stator terminals to generate electrical power in the generating station.
• This generated power is fed to the generating step up transformer to make this medium voltage level to higher level, i.e. up to 33 kV.
• Power at 33 kV is sent to the generating substation. There the transformer increases the voltage level to 66 kV or 132 kV.
• From this generating substation power is sent to the nearer substation to increase the voltage level higher than previous. This level of voltage is increased at different suitable levels, it may be at 400 kV or 765 kV or 1000 kV. This high voltage or extra high voltage level is maintained to transmit the power to a long distant substation. It is called primary transmission of power.
• At the end point of primary transmission of power, in the substation, the step down transformers are used to step down the voltage level to 132 kV. Secondary transmission of power starts from this substation.
• Power transformer at the end of the secondary transmission, just makes 132 kV voltage level steps down to 33 kv or 11 kV as per requirement. From this point, the primary distribution of power starts to distribute power to different distribution stations.
• At the end of the primary distribution, the distribution stations receive this power and step down this voltage level of 11 kV or 33 kV to 415 V (Line Voltage). From these distribution stations to consumer ends, 415 V is kept to sustain for utilization purpose.

Voltages in Power Transmission Lines or Transmission Voltages | Electrical4U

 

[mazers]

Can you please stay on topic about AC vs DC. Thank you.

Isn't the thread topic about Enhanced Summon? I do

Can you please stay on topic about AC vs DC. Thank you.

ACDC hijacked the Enhanced Summon thread.

 

[NoMoGas]

I stand corrected

 

[hill]

Isn't the thread topic about Enhanced Summon? I do


ACDC hijacked the Enhanced Summon thread.

That was so last ½ a year ago.
.

 

[XHabjab]

...

Yup, I'm questioning AC (Alternating Current) for the solar home. Does it still make sense? The sun, batteries, lights, all DC oriented! And get this from Google search... "the DC motor is 30% more efficient than AC motors due to the secondary magnetic field being generated from the permanent magnets rather than copper windings." Last I checked, my car also uses a DC motor for these reasons. And gee, the battery is DC too.

I believe all drive motors in Teslas are 3 phase with switched DC on each winding. So there is indeed DC input, but an expensive and proprietary bunch of electronics driving the 3 phase (ie. not DC) motor.

...
The switch-over would be painful at first - not many DC refrigerators out there but they are available so I'm thinking long here. For a random example: Appliances | Off-Grid | Solar Appliances | Backwoods Solar

Kinda crazy we take solar, charge batteries, then convert to AC for the car which turns it back to DC. Energy lost at every conversion.

Converting your house from 120VAC to ???VDC is not a good idea. You would be able to use existing wiring but switching would be different. A DC switch is much larger, needs maintenance and fails more frequently, and fails in a most spectacular fashion.

 

[SOULPEDL]

Ummmm DC has a VERY high loss rate per foot which is why your cables are so thick. Want to rewire your house in 8 gauge wire? This is why we use AC.

Ummmmm, OK.

I believe all drive motors in Teslas are 3 phase with switched DC on each winding. So there is indeed DC input, but an expensive and proprietary bunch of electronics driving the 3 phase (ie. not DC) motor.

Converting your house from 120VAC to ???VDC is not a good idea. You would be able to use existing wiring but switching would be different. A DC switch is much larger, needs maintenance and fails more frequently, and fails in a most spectacular fashion.

The switch problem can be managed by taking care of arcing. This is done by constantly breaking the voltage very quickly to lose the spark (AC does this by nature). I read last night about the voltage and people think 36V or maybe 48Vdc will be the final standard. It didn't sound like an if thing from what I'm reading, but more of a when. There is a lot out there on this topic. FYI, I'm not seriously considering, more of a wonder why not.

Meanwhile, I had a visit today from Tesla and SRP management for my solar layout conundrum. Talk about complicated!

 

[XHabjab]

HVDC links are lower loss compared to AC links always, not just when using superconductive cables (which are crazy rare). But I only know of HVDC facilities being used as large transmission trunks, where it's then converted to AC for distribution. The reason transmission lines and normal wire for DC is smaller gauge than AC is that AC tends to only use the surface of a conductor whereas DC uses the entire conductor.

The problem is that HVDC conversion is SUUUUUUUPER expensive. DC transmission attempts to recoup these costs by using smaller gauge wire and a reduced conductor count. But this only works when distances are extremely long and conductor material is expensive. Also, conversion has become cheaper but not nearly "cheap enough" and it's very failure prone. There are countless conditions that cause converter facilities and circuit breakers to fail catastrophically. And I mean catastrophically. The low availability of components to repair these systems usually means longer down times and higher repair costs, so using HVDC for anything except tying multiple grids together without needing to sync them all is somewhat unheard of these days.

Sorry we're still way off topic here, but there are 3 main reasons for using an HVDC transmission line:

1. Lower loss as you state here, although this is a minor reason.
2. The Ferranti effect, described here. As a transmission line gets longer and longer, the load side will see extremely large voltages when the line is energized ("brought online"). This was the reason that the New York power failure (in the 1970s?) took a week to turn back on. The power lines feeding the city had never been shut down and they had to develop a plan to turn everything back on again without overvoltage problems and tripped breakers.
   
3. Stability of the transmission line and related control systems. When a power line gets longer, it is harder to control. The speed of light on a 60 Hz transmission line means that actual and observed voltage will be about one cycle off between both ends at about 500km. If a short circuit or overload occurs, it takes several cycles for the fault to be detected and breaker tripped and the line shut down. This can be catastrophic to the generation equipment, the line and possibly the load (that's you and me).

HVDC transmission lines that I am aware of:

• Pacific DC Intertie in California. It seems to be about 850 miles in length.
• Nelson River DC Lines (3) in Manitoba Canada. Three lines that are 556 miles, 582 miles and 852 miles in length.
• Something in Russia (?)
• Something in Sweden (?)

So, is enhanced summon here yet?

 

[john85775]

Enhanced Summon will be a massive let down and we all know it. Hell even summon fails a good amount of the time with interrupted connections or some other fail when I’m standing right next to the damn thing.

 

[cucubits]

Enhanced Summon will be a massive let down and we all know it. Hell even summon fails a good amount of the time with interrupted connections or some other fail when I’m standing right next to the damn thing.

Psst, duuude, come on man, don't spoil it

 

[ebmcs03]

Enhanced Summon will be a massive let down and we all know it. Hell even summon fails a good amount of the time with interrupted connections or some other fail when I’m standing right next to the damn thing.

Mine won’t go straight in my driveway. There’s a bush on the right and nothing on the left. So it won’t go straight. It always turns left and tries to run itself off the driveway and into the dirt road.

 

[cgiGuy]

No. Relax, you'll know when it is out.

 

[kavyboy]

No. Relax, you'll know when it is out.

Yes. Look for the thread "Who is really at fault if nobody's driving" or "Parking lot traffic jam".

 

[Nocturnal]

Enhanced Summon will be a massive let down and we all know it. Hell even summon fails a good amount of the time with interrupted connections or some other fail when I’m standing right next to the damn thing.

Mine has improved a crazy amount since I've had the car. I don't think this follows though. Summon fails when it loses connection to the phone, I'm not thinking enhanced summon will have this issue.

If enhanced summon sucks then we should wrap up any ideas about FSD and should all dump our stock.