Meter Register Content Codes

Author: Malcolm Souness, Director, 221b Ltd
Originally published 29 October, 2019, updated January 2020

The source data used for this analysis are taken from the Electricity Authority of New Zealand EMI website. The R statistical analysis package is used to transform and present the data in a more useable form, source code available from the 221b Data Refinery Github Repository. The key constraint on this dataset is the exclusion of de-energised sites (ICP Status 001).

The NZ electricity industry uses a specific set of "content codes" and "period of availability" to describe the period of availability and flow of energy to customers. Whilst these include half-hour based total registers, such as 7304 for energy and 7306 for reactive energy, we will consider only the non half hour (NHH) register content codes. The aggregate of these with the "period of availability" inform the electricity retailer's billing system of what tariff rates should be applied to each register of the customer's meter, which in-turn defines the price paid by the customer for the energy recorded. To complicate this further, advanced meters can record voltage, current, outage and tamper events. These will be the subject of future discussion.

A meter register is a discrete counter that records the volume of energy passed through the meter to a specific supply at the customer site. The number of meter registers can impact the cost of metering for the customer site, and add to the complexity of data management downstream from the meter (at the electricity registry, the meter owner, the electricity retailer and the electricity network owner).

For example an "uncontrolled" supply delivers electricity 24 hours per day without interruption, whereas a controlled supply has constraints on the availability of supply.

"Controlled" supply is provided (in addition to uncontrolled supply) at the discretion of the electricity network company. The network offers a discounted rate in return for the guarantee of reduced energy use on the network during times of peak demand.

Whilst peak periods may occur during cold winter nights, controlled supply is generally automated to limit availability on a diurnal basis (time of day). The use of "day/night" supply combinations can also incentivise the customer to use energy outside of peak times. Other combinations exist, such as "peak/off peak/shoulder" supply, where the day is split into multiple time zones.

The use of "all inclusive" supply is a combination of uncontrolled and controlled supply, all supplied by a single channel meter, recording the blend of uncontrolled and controlled energy use at the customer site. This requires less complexity in meter configuration and installation, and lower cost of meter lease paid by the electricity retailer to the metering equipment owner (MEP).

Where on-site generation is deployed, with an expectation of energy flowing into the electricity network from the customer site, an "embedded generation" register content code is employed. This advises the electricity retailer of the meter register that should receive a credit, rather than a debit tariff for energy recorded.

Registers per Electricity Network

The number of meter register content codes is presented, with the number of registers broken down by each major electricity network region. The majority are uncontrolled (UN), inclusive (IN) and controlled (CN).

NHH Electricity Meter Register Content Codes per Electricity Supply Network Across NZ.

Interesting Details

Generation ("I" flow) registers without EG coding - the customer can be charged for electricity generated, rather than credited.

Generation registers without 24 hours availability - generation is expected to be EG24, less hours available indicates generation disconnection during part of day.

Where the direction of load flow is indicated as "generation", but the register content code indicates load, does the customer get credited for energy use, does the market credit volume consumed to the Retailer?

Uncontrolled ("UN" code) registers without 24 hour availability - the customer should be eligible for discounted controlled supply if the period of availability is less than 24 hours per day.

The use of 24 hours availability for register content codes other than uncontrolled, all day or generation indicates incorrect use of 24 hour supply availability.

Wide range of controlled ("CN" code) registers of varying period of availability, adds to the complexity of configuring and billing customers accurately.

There are other issues with electricity meter registers, however those warrant investigation for each individual network.