How NULL values are handled for Electricity
Missing values in Power and Power Quality data can result from bridge/gateway disconnections, device disconnections, unsupported metrics, or devices returning NULL values. Handling depends on the device type: devices that cannot distinguish between NULL and 0 convert missing values to 0, while devices that can distinguish between them show NULL as missing data (Power Quality Dashboard) or convert it to 0 (Power Dashboard).
Missing value handling for Power & Power Quality
When Can Missing Values Occur?
Missing values can occur in the following situations:
1. Bridge/Gateway Disconnection
If the bridge or gateway that transmits data from the device disconnects, no data is received by the platform.
To verify this:
- Open the Status page via the button in the top-right corner of the Sensorfact web app.
- Navigate to the Bridge/Gateways tab.
- Check the Last seen timestamp to see when the latest update was received.
If an individual sensor or device disconnects, it will stop sending data.
To verify this:
- Open the Status page.
- Navigate to the Sensors tab.
- Check the connectivity status of the device.
3. Device Returns NULL or Unknown Values
A device may remain connected but return NULL or unknown values.
In this case, the platform continues receiving data, but some measurements contain NULL values.
4. Metric Not Supported by the Device
Some devices measure only a subset of available power quality metrics.
For example:
If a device measures voltage, current, and power, but not power factor, the power factor field will contain missing values.
How Are Missing Values Handled?
Handling of missing values depends on the device type and whether the system can distinguish between NULL and zero (0) values.
Devices That Cannot Distinguish Between NULL and 0
Example: Current clamps
Current clamps rely on measured current to operate.
If no current is measured, the device cannot send data.
In this case:
- NULL or missing values are transformed into 0 in the platform.
- No distinction is made between NULL and zero.
Devices That Can Distinguish Between NULL and 0
Example: Power meters
Power meters can transmit explicit 0 values because they do not depend on measured current to operate.
Handling differs per dashboard:
Power Dashboard
- All NULL values are transformed into 0.
Power Quality Dashboard
- A distinction is made between NULL and 0:
- NULL values are displayed as missing data (trend lines are broken).
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- 0 values are displayed as 0.
If for the selected devices there is only missing data for the selected timeframe, the platform provides a general no data statement as follows: