Sustained maximum current Goals

This topic

and many others like it regarding 400A or multi-panel support point to the benefit from an addition to the Goals features. Namely:

To add the ability to alert for short sustained current and not simply “at any point” usage.

Unlike this request/answer:

Potentially, this feature could be hidden by Sense and simply a default “approaching 80% sustained current limit” for the CTs or somesuch default for 200A service.

Strictly speaking this would be an alert for current rather than watts.

Ideally some user-accessible stats would be presented in the Goals UI or Signals.

The primary motivation behind this feature would be safety and failure prevention but the added benefit would be in assessing a system over time … warning users not that they are using lots of watts over long periods of time but that they are experiencing high loads for short periods. This slots into general Device-failure detection but is more of a house-wide failure detection (potential) separate from device detection.

I’m not completely understanding. When you mention this for “current”, then that is amperage, not wattage.
What would be high for 120v would not be for 240v. I do t think differentiates between 120 and 240 devices as it see everything as 120.
How would that work in a situation like where I live? The voltage on one leg is 125 most of the time.

Remembering that the aim would be to preempt (alert for the potential of) breaker tripping or wire overload, i.e. avoid sustained high current situations that are close-to but not sufficiently high to trip a breaker or overload a wire.

The Current Transducers (CTs) are just that: current sensors.
The mains voltage in detected by the Sense wired inputs.
The combination of those two inputs yields a power measurement (watts) but that is not needed for over-current (or under-current for that matter) measurement … the voltage (on the mains) only matters in so far as if it fluctuates the current will likewise fluctuate. Because of the relatively stable mains voltage, one can infer the current from the power but Sense is monitoring current and voltage to infer power so with access to that instantaneous current measurement there is no hardware impediment (other than implementation – maybe processor load?) to measuring (integrating) short-period sustained current. I assume to a certain extent this is already done.

There are several implementations that could work.

  1. Sense could set a hard current limit (alert) for sustained load that approaches >80% or whatever of the CTs rated maximum. [This could be invisible to the user and simply a known feature. It may well exist already!?]

  2. Sense could allow for user-input limits to match, say, lower main breaker and/or wiring. e.g. If you have a 100A panel and mains breaker you would want a lower limit that Sense cannot auto-magically detect. This would imply some UI mods.

  3. Same as above but add the ability to arbitrarily define limits regardless of the mains limits. e.g. You have an EV fast-charger with it’s associated high current draw that you worry might push the limits of your supply.
    BTW: This could also be relevant to the solar CTs; here is also where an under-current limit becomes interesting to ponder.

Sustained current can be inferred from the “Usage” (and existing Goals) but the time periods for pre-empting breaker tripping are potentially much shorter than these settings allow. Beyond that, as with the first implementation above, this is not something that necessarily needs a UI.

Here’s a 100/125A main breaker trip curve to ponder. e.g It will take perhaps almost an hour for one of these 100A main breakers to trip at near the rated max.; at 200A, about 60s; at 600A about 10 sec. In the meantime, you gotta wonder what’s happening. More here:

https://www.schneider-electric.us/en/download/doc-type/1555860-Tripping+curves/.

736-05

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