4 ms·

There is a good Volts[1] episode[2] on it. TL;DR the thing that limits how much power a line can carry is heat dissipation, which depends on weather. We used si

There is a good Volts[1] episode[2] on it. TL;DR the thing that limits how much power a line can carry is heat dissipation, which depends on weather. We used simple heuristic models to back out what we considered safe operating currents historically, but if you use sensors to enable a more data-intensive approach, you can operate closer to full capacity. [1] https://www.volts.wtf/ https://www.volts.wtf/ [2] https://open.spotify.com/episode/4sqNcVcXdLF3QFDR6f5Vgd https://open.spotify.com/episode/4sqNcVcXdLF3QFDR6f5Vgd

tuatoru 3y ago
So an alternative title is " ... is reducing safety margins by 50%". (Sensors sense what they are designed to sense, not other things, and sometimes lose calibration.)
- toomuchtodo 3y ago
  Operating with unnecessary margin is wasteful and does not necessarily increase safety.
  - gtvwill 3y ago
    Said no ohs advisor ever. Engineering in buffer for safety is one of the most common practices. I mean hey if you wanna roll the dice standing up next to some high pressure hydraulic gear on machinery that's running a few psi away from failure because it's super efficient be my guest. But I'm not gonna enjoy the one day in 10000 when something goes a Lil awry and you get cut in half because old mate ordered hoses without steel sheathing because the unsheathed ones were rated for the same pressure but were cheaper and more cost efficient. That's some 1950s old world business ideology there. Also another example. All lifting straps for cranes and lifting hardware is generally capable of 3x to 4x its safe working load. Buffers are everywhere and they save lives.
    - AnthonyMouse 3y ago
      Accuracy and safety margins are two different things. Suppose you have to spec the capacity of a line regardless of what temperature it is, because you're not going to measure it in realtime at all. You estimate the highest temperature will be 105 degrees F, calculate the capacity at that temperature, add e.g. a 20% safety margin, and call that the capacity of the line. That means when it's 40 degrees F, you could be operating with a 200% safety margin, which is unnecessarily conservative and wasteful. Conversely, because you're not measuring the temperature at all, your high temperature estimate could be wrong and there could be a day that it's 115 degrees F, your safety margin is completely gone and the line burns out. Whereas if you were monitoring the temperature, you'd lower the capacity of the line that day to still have a 20% safety margin and not have problems.
    - fastneutron 3y ago
      This is a timely debate in engineering. Historically, it would be customary do the most conservative reliability analysis possible, right up to the point of accounting for physically impossible parameter combinations, just to ensure enough margin to trade at some point in the future when things inevitably don’t go as planned. Now, technology has advanced to the point where all the low hanging fruit are gone in terms of performance optimization, and we’re better able to determine how close to the “cliff” we are, with tighter uncertainty bounds, than ever before with probabilistic design methods. By this logic, we should be able to squeeze out margin that was never needed (or never there) in the first place. No safety professional would trade away margin you say, but the engineer is often between a rock and a hard place when a few percent traded away in margin translates to multiple millions of dollars in cost reduction or profit. Is it unethical to remove margin if your Bayesian UQ calculations are saying you’re still safe, if not safer than you were under the other methodology? This tension is going to keep on building as AI-enabled solutions start penetrating more and more into traditional engineering fields, with as-yet unknown consequences.
      - slt2021 3y ago
        trading margin is perfectly fine if there are compensating mechanisms. for example automatic circuit breakers and other sensors and actuators that can reliably respond to the critical conditions if we can double the line current by trading margin, and only need to add few sensors and automatic breakers here and there - thats perfectly fine. You will double your current without building a new line basically
- xnzakg 3y ago
  > So an alternative title is " ... is reducing safety margins by 50%". Not necessarily. The _actual_ current limit depends on the climate conditions, and with static line rating the safety margin actually varies. So while dynamic line rating might reduce the safety margins when the conditions allow running more current, it can also increase the safety margin in case of a particularly hot summer.
- outside1234 3y ago
  The safety margins are still the same -- just using a lookup table based on temperature vs. assuming worst case.
  - deleted 3y ago
    [deleted]

tuatoru 3y ago

So an alternative title is " ... is reducing safety margins by 50%". (Sensors sense what they are designed to sense, not other things, and sometimes lose calibration.)

toomuchtodo 3y ago
Operating with unnecessary margin is wasteful and does not necessarily increase safety.
- gtvwill 3y ago
  Said no ohs advisor ever. Engineering in buffer for safety is one of the most common practices. I mean hey if you wanna roll the dice standing up next to some high pressure hydraulic gear on machinery that's running a few psi away from failure because it's super efficient be my guest. But I'm not gonna enjoy the one day in 10000 when something goes a Lil awry and you get cut in half because old mate ordered hoses without steel sheathing because the unsheathed ones were rated for the same pressure but were cheaper and more cost efficient. That's some 1950s old world business ideology there. Also another example. All lifting straps for cranes and lifting hardware is generally capable of 3x to 4x its safe working load. Buffers are everywhere and they save lives.
  - AnthonyMouse 3y ago
    Accuracy and safety margins are two different things. Suppose you have to spec the capacity of a line regardless of what temperature it is, because you're not going to measure it in realtime at all. You estimate the highest temperature will be 105 degrees F, calculate the capacity at that temperature, add e.g. a 20% safety margin, and call that the capacity of the line. That means when it's 40 degrees F, you could be operating with a 200% safety margin, which is unnecessarily conservative and wasteful. Conversely, because you're not measuring the temperature at all, your high temperature estimate could be wrong and there could be a day that it's 115 degrees F, your safety margin is completely gone and the line burns out. Whereas if you were monitoring the temperature, you'd lower the capacity of the line that day to still have a 20% safety margin and not have problems.
  - fastneutron 3y ago
    This is a timely debate in engineering. Historically, it would be customary do the most conservative reliability analysis possible, right up to the point of accounting for physically impossible parameter combinations, just to ensure enough margin to trade at some point in the future when things inevitably don’t go as planned. Now, technology has advanced to the point where all the low hanging fruit are gone in terms of performance optimization, and we’re better able to determine how close to the “cliff” we are, with tighter uncertainty bounds, than ever before with probabilistic design methods. By this logic, we should be able to squeeze out margin that was never needed (or never there) in the first place. No safety professional would trade away margin you say, but the engineer is often between a rock and a hard place when a few percent traded away in margin translates to multiple millions of dollars in cost reduction or profit. Is it unethical to remove margin if your Bayesian UQ calculations are saying you’re still safe, if not safer than you were under the other methodology? This tension is going to keep on building as AI-enabled solutions start penetrating more and more into traditional engineering fields, with as-yet unknown consequences.
    - slt2021 3y ago
      trading margin is perfectly fine if there are compensating mechanisms. for example automatic circuit breakers and other sensors and actuators that can reliably respond to the critical conditions if we can double the line current by trading margin, and only need to add few sensors and automatic breakers here and there - thats perfectly fine. You will double your current without building a new line basically
xnzakg 3y ago
> So an alternative title is " ... is reducing safety margins by 50%". Not necessarily. The _actual_ current limit depends on the climate conditions, and with static line rating the safety margin actually varies. So while dynamic line rating might reduce the safety margins when the conditions allow running more current, it can also increase the safety margin in case of a particularly hot summer.
outside1234 3y ago
The safety margins are still the same -- just using a lookup table based on temperature vs. assuming worst case.
- deleted 3y ago
  [deleted]