Estimated Usage and Metered Usage

Estimated usage

Estimated usage is based on order data and is calculated by determining how much flow has been delivered to an outlet since the last meter reading and up to the effective date of the new meter reading.

Metered usage

Metered usage is calculated in three ways:

• If meter readings are entered manually, the metered usage is calculated by determining the difference between two sequential meter readings. If the metered value is negative, the value is re-calculated by assuming that the meter was reset at its standard maximum setting.

  Note

  The maximum setting is set in the Max Meter Reading attribute for the service point.

• If the readings are manually read from remote meters, the reading is read from the host accumulator count tag (the current volume for the season) and the volume is calculated as the difference from the previous reading as for a manually entered reading. See the DMS Accumulator module documentation for more information about accumulators.
• If meter readings are read automatically by TCC, the meter is read as soon as the flow has stabilised at zero after the order is completed. The reading is read from the host accumulator count tag, and the usage is calculated by summing the accumulator increment tag values since the last reading. See the DMS Accumulator module documentation for more information about accumulators.

Automatic adjustments

These two adjustments may be performed automatically. The Meter Reading Adjustment screen opens to display the results of any automatic adjustments.

• Small wheel adjustment - water usages calculated for meters with small wheels must be adjusted. A standard small wheel adjustment can be specified for the system using the Small Meter Adjustment Percentage attribute.
• Low flow adjustment - where the flow rate is below the low-flow threshold for all or part of an order, a low-flow adjustment is automatically applied to the calculated usage. This calculated usage is displayed in the Meter Reading Adjustment screen where you can accept the calculated usage or make changes.

Resolving conflicts

When metered usage is significantly different from estimated usage, you are prompted to either adjust the meter reading, or confirm that it is correct. In either case you must provide a reason for your choice.

To determine whether the difference is significant, the system checks two parameters:

• Meter Read Variation Ranges - this parameter sets up usage ranges. Different tolerance threshold s can be applied to each range.
• Meter Read Variation limits - this parameter sets the tolerance thresholds for each range.

A third parameter, Meter Read Variation No Flow limit, sets a maximum metered usage for outlets where the estimated usage was zero.

Allowing for meter creep

You can use the Meter Reading Usage Threshold parameter to suppress frequent small readings caused by meter creep. This parameter sets a lower limit for recording meter readings.

See Metering Parameters for more details.