Account for an accumulator's rollover

At a certain point, the accumulator device used to gather the information that the metering device is reporting will reach its maximum value and reset to zero. The maximum value at which it resets to zero or "rolls over" is defined in the Accumulator Rollover property.

Meters that are configured as accumulator meters calculate change by subtracting the previous volume from the current volume.

If you have reached the point at which it is time for the accumulator to roll over, the resulting value will be negative.

Consider the following example:

Accumulator Rollover: 16,000,000

Current volume accumulation: 1,284

Previous volume accumulation:15,983,717

In this case:

Current volume accumulation (1,284) - Previous volume accumulation (15,983,717) = -15,982,433

The system accounts for the rollover by adding the Accumulator Rollover value + 1 to the current volume accumulation.

In the example given, the current volume accumulation would be calculated as follows:

Current volume accumulation (-15,982,433) + Accumulator Rollover (16,000,000) + 1 = 17,568

If your data does not arrive in chronological order

In the event that your data does not arrive in chronological order, you may be in a position where more than one row needs to be accounted for.

Consider the following:

Data arrives at 10 AM as expected. However, the 11 AM data does not arrive until shortly after the 12 PM data. Because the system has already had time to process the information from 10 AM and 12 PM, the arrival of the 11 AM data may trigger a recalculation of the 12 PM row.

10 AM - Volume that was previously processed, in the position of "Previous Row"

11 AM - Volume that is currently being processed, in the position of "Current Row"

12 PM - Volume that was previously processed, in the position of "Next Row"

The value in the position of Next Row is calculated as follows: Next Row - Current Row. If there is a rollover at that time, resulting in a negative value, the Accumulator Rollover value + 1 will be added in order to account for the rollover.

Consider the following example:

Accumulator Rollover: 16,000,000

Next Row: 1,284

Current Row: 15,983,717

Next Row (1,284) - Current Row (15,983,717) = -15,982,433

-15,982,433 + Accumulator Rollover (16,000,000) + 1 = 17,568

Unit conversion consideration

The values the accumulator reports need to be interpreted in light of the units of measure being used. Measurement assumes that the Accumulator Rollover reflects the maximum value that all of the accumulators within the device can report. The rollover value plus the extra count will be converted to the appropriate units for calculating the value from each accumulation value provided in the data.

This means that, for each value reported by the accumulator, the rollover will be converted to the appropriate units to properly interpret the meaning of the accumulator reading. For example, if your accumulator is intended to supply a volume reading, the system would perform the following correction on the data.The rollover value + 1 would be converted from the Input Unit Profile volume units to the volume units that are used internally to calculate the data before it is added to the volume value.