Voltage and current card

Who it’s for

For anyone who thinks in terms of “nominal, plus or minus a tolerance” rather than a raw threshold number — a plant electrician at a switchboard watching for phase imbalance, the classic early sign of a burning three-phase motor; a duty engineer on a UPS deciding whether the input has sagged enough to bring up the generator; a service engineer checking whether a solar inverter’s string voltage has drifted outside its expected range; an operator confirming a diesel generator actually reached nominal in its first thirty seconds after starting; or a mechanic watching a pump’s current creep above normal, the kind of drift that shows up weeks before a bearing fails.

What it does

Reads voltage and/or current for either a single phase or three phases, and renders each live value against a nominal band you define — nominal plus a tolerance percentage, the way an electrician actually thinks about it, rather than a raw threshold number you’d have to reverse-engineer:

• Phase mode (Single-phase or 3-phase) is a setting, and only the key-name fields relevant to that mode are shown — four fields, not eight.
• A position bar under every value — voltage and current alike — shows where the reading sits on a scale twice as wide as the tolerance, so an out-of-range value visibly lands outside the highlighted valid zone instead of just clamping to the edge with no sense of how far out it is.
• In 3-phase mode, a single Phase imbalance figure (the spread between the highest and lowest phase, as a percent of nominal) appears with its own warning threshold, plus a badge in the header when it’s exceeded.
• A phase that’s missing or stale renders as a dash in its own status color — it doesn’t take down the whole card, and doesn’t get silently dropped from the layout either.
• Nobody thinks “alarm at 207 volts” — they think “230 nominal, 10% tolerance.” The settings match that mental model, and every boundary shown on the card is computed from it.

How to set up

1. Add Voltage and Current Card to a dashboard state.
2. Choose Phase mode under Settings → Phase mode — Single-phase or 3-phase.
3. Under Settings → Voltage and Settings → Current, set the key name fields to match whatever telemetry or attribute keys are actually bound on the Data tab.
4. Adjust Nominal and Tolerance (%) for both Voltage and Current to match the real circuit — the defaults (230V, 10A, ±10%) are just a starting point.

How to customize

• To change what counts as in-range — adjust Nominal and Tolerance (%) under Settings → Voltage or Settings → Current.
• To change the imbalance warning level — adjust Warning threshold (%) under Settings → Imbalance; the badge and the imbalance figure’s color both follow this threshold.
• To change status colors — adjust In-range color, Out-of-range color, Missing phase color, and Imbalance color under Settings → Display.
• To hide the imbalance badge — turn off Show imbalance badge under Settings → Header.
• To hide the last-updated time — turn off Show last updated under Settings → Display.
• To restyle the text — adjust Label font and Value font under Settings → Display.

Notes

• Voltage and current keys are matched by literal key name (set once per widget instance under Settings → Voltage/Current), not a per-key Role field — faster to configure across many instances, but it means devices with different underlying key names need their own widget instance settings.
• Phase mode is a manual switch rather than being inferred from which keys are bound, since that’s what makes it possible to show only the four relevant key-name fields instead of eight.
• Phase imbalance is calculated from Voltage only, shown as one figure rather than a separate number for each quantity — the electrical term “phase imbalance” is a voltage concept, and current draw already gets its own visible per-phase reading.
• The last-updated time uses moment.js, already available in the ThingsBoard widget environment.