This report discusses the development of a cost effective communications system with electronic metering and examines the costs and benefits of Australia's largest remote metering installation to date.
Admiralty Towers Building Two, a residential complex located in Brisbane's central business district overlooking the Brisbane River, was selected for the site of the trial. This 36 storey tower contains a total of 216 luxury apartments on a combination of single and three phase electricity supplies.
MeterNet, the communications system used in the project, was developed by Nilsen Industrial Electronics Ltd of Melbourne. It is a remote meter reading and control system for their EMS2600 series of electronic single phase electricity energy meters. The Admiralty Towers installation consists of 375 EMS2600 meters with 20mA series current loop communications options. Four MeterNet servers located on the fifth, fourteenth, twenty-third and thirty-second floors connect the 375 meters. A fifth MeterNet controller is located in the basement, connecting the MeterNet servers through a modem to the Public Switched Telephone Network (PSTN).
Before MeterNet development began, the design philosophy and objectives were established. The basis of the design philosophy was to develop a system based on standard products and proven technology. We wanted smart meters and meter communications infrastructure that are cost effective and presently available, rather than `dumb' meters and smart communication networks that could become stranded assets in future.
We identified the need for a simple and robust NC4000 server which would be easy to install and test and would not require special setup or configuration at the site. We wanted to avoid using an intelligent concentrator that requires configuration and parameters to be set, many of which are site specific and must be mapped in the server and modified as changes occur.
In addition the design had to be flexible, to allow systems to be sold and installed in small and large installations to suit customer requirements.
A further requirement was that existing utility staff had to be able to install, service and operate the system with minimum training and with a high level of success. Special skills and training should not be required.
The software had to run on existing standard utility PCs, running under Windows 3.11. Special computer hardware equipment or software should not be required. In addition the software should be easy to customise, modify, test and maintain, scalable for small or large systems, and portable to large multi-user database systems.
The design objectives of MeterNet were to;
- Provide remote reading of meters (AMR).
- Improve the accuracy of reading compared to manual reading.
- Provide a low cost interface for MeterNet, i.e. <$20 per meter.
- Allow a single point of access for ease of communication, either local or remote.
- Provide for networking of meters.
- Ensure security for owners and for utility personnel - a selling feature for developers.
- Allow stand-alone meter operation and administration. The PC should contain a database of meters with customer account numbers, error status of meters and operation parameters.
- Reduce operating costs of the electricity utility retailing arm. Opening new accounts and closing accounts should be performed remotely. First reading or last reading, connect or disconnect, new tariff entries, clearing tamper indication and meter diagnostics should all be able to be carried out to a high level of confidence without requiring a special site visit.
The three components of the MeterNet system are meters (single and 3 phase), NC4000 servers and MeterSoft).
The NC4000 server supports 12 down-stream ports. Each port can communicate over a distance of 1000 metres with up to 12 meters, providing a capability of 144 meters per NC4000. For applications where more than 144 meters are required, the controllers are cascaded to allow a virtually unlimited number of meters.
The NC4000 is designed to provide a low cost unit with high reliability - for example, it can withstand mains voltages on the loop. Protection against overvoltage and cable reversals has been provided, along with local access to allow testing of the networking environment. Access is available at the NC4000 via a local optical port, or remote via a modem and PSTN line.
The ideal site
MeterNet features and possible application will be shown to best advantage where a site meets at least some of the following criteria.
Size: A minimum of 20 units, not necessarily restricted to residential units.
Early introduction: MeterNet systems are easier to introduce at the early planning stage, so the developer and contractor can obtain all the benefits at the least cost, rather than as a retrofit operation when access is difficult.
Multi-storey developments: MeterNet is easier to install in high rise multi-storey complexes, as meters are more likely to be grouped together on meter panels where wiring is easy and simple to install. Also meter access for the utility is more likely to be an issue for building owners and occupiers of high rise buildings.
Affluent consumers: Affluent consumers in high rise apartments are more likely to require security, which provides a reason to install MeterNet. These consumers are likely to be future contestable customers, requiring frequent reading and other services provided by the system.
Load control: Load control necessitates a two element meter such as the EMS2600. The incremental cost of MeterNet meters is low compared to two single element meters and a ripple receiver (which may not function due to poor signal) or a time switch.
High consumer turnover: Residential units with a high turnover of consumers require unscheduled meter reads which are expensive. MeterNet lowers cost by pro-viding an alternative remote reading method.
Location constraints: With access regularly required by meter readers and utility personnel, the location of meters in groups on meter panels with easy access creates demands on the developers and builders. Installing a MeterNet system may ease some of these constraints.
Sub-metering: The need for sub-metering of a complex such as a shopping centre or industrial site, in order to provide energy consumption information so that internal costs can be allocated or individual loads monitored, assists in the justification of a MeterNet installation.
The Admiralty Tower installation
At Admiralty Towers all system operations are performed from PC based software (MeterSoft) using a standard PSTN modem to establish communications to the meters. The system requires the operator in the utility's offices to initiate all operations. There is scope in the future to develop a fully automated reading system, but additional mainframe billing interfaces will be required.
Admiralty Towers consists of three customer categories - 192 domestic customers, two commercial whole current customers and one body corporate CT metering for the community services.
There are 102 single phase domestic customers, each with one two element electronic meter fitted with disconnect relay and serial current loop communications option, and 90 three phase domestic customers, each with two single element meters and one two element meter. All three meters are fitted with disconnect relays and serial current loop communications option.
The building services are metered by one electronic polyphase meter fitted with remote RS232 communications connected to 800/5 metering CTs. Two other commercial metering positions are on site, supplying a coffee shop and public lighting for the broad walk and nearby park. This metering is whole current via single element meters fitted with disconnect relays and a serial current loop communications option.
All the metering, with the exception of the one electronic polyphase meter, is remotely interrogated by the MeterNet communications system.
MeterNet uses a 20mA serial current loop communications system as set out in draft IEC specification IEC1307. Between 8 and 12 meters are connected in series using telephone type cable terminated via KRONE quick connect connector blocks. Each group of 8 to 12 meters is connected to an NC4000 server which acts as a data concentrator.
Four servers are used, one located every ninth floor. These in turn are connected to a server located in the basement, which acts as a master server. The server is connected via an RS232 connection to a DataGate multi-port modem, allowing dial-in access from the PSTN. System security is provided by the security features of the DataGate and by the internal password of each meter.
The electronic polyphase meter metering the community load is connected directly to DataGate via RS232, allowing it to be read and interrogated by the MV90 system.
The NC4000 servers are basically data concentrators which provide the distribution of communications traffic around the communications network. Each server contains one upstream port and 12 downstream ports. The upstream port receives communications packets from the computer for distribution to the downstream ports.
The downstream ports echo out communication commands that have been received from the upstream port. Communication commands received from any one of the 12 downstream ports is then echoed through to the upstream port. Each of the 12 downstream ports can have up to 12 meters in series.
MeterNet servers are used on every 9th floor, located behind the meter panels on the 5th, 14th, 23rd and 32nd floors.
Now that the system is up and running, the following benefits have been identified.
Reduced meter reading costs. Meter reading costs are reduced as all the meters are read remotely within 30 minutes, and all the billing data is transferred electronically to the billing database.
Increased safety of SEQEB and contract staff. The danger of dogs and irate customers (on disconnect for debt) is substantially reduced, as most on-site service visits are eliminated. The only visits required are to perform reconnections, which is done by pressing a button on the front of the meter once the meter has been activated remotely for reconnection.
Fast resolution of account queries. As there can be no meter reading transcription errors, customer complaints are lower. On-line resolution of account queries is available to resolve customer complaints.
Improvement in revenue protection. The system enhances revenue protection by providing tamper flags and the ability to offer total metering system audits. It also reports situations of reverse energy, which indicate that a customer may be using a Black Box in an attempt to reduce energy consumption. In addition, bulk metering on the main supply to the building allows reconciliation between the total metering and all the individual domestic meters.
Reduced costs for tariff change. The system allows the customer's tariff to be changed on-line in seconds, thus eliminating visits by service personnel. This results in cost reductions.
Reduced disconnect for debt costs. Disconnect for debt costs will be substantially reduced, as disconnections can be done remotely and field calls are totally eliminated.
Improved security for customers. The customer enjoys a higher degree of security, as `trespass' or entry of utility personnel onto the premises to read meters is eliminated.
Tariff analysis opportunities. The system can hold five different tariff configurations to cover most of the current tariff combinations. It can also provide load profile information for each meter, to assist in analysing consumption patterns. This can be used for marketing purposes.
Interruptible loads for CBD. Interruptible loads have not been available within the CBD because of the absence of the Audio Frequency Load Control system. With the MeterNet system SEQEB will be able to shed hot water and other controlled loads during times of peak loads and system instability.
TOU tariff opportunities. The metering installed at Admiralty Towers can handle up to eight Time Of Use rates. If SEQEB wishes to trial TOU tariffs or options, the system can operate on both the TOU and the existing tariff combinations at the same time.
Reduced cost of general electrical reticulation. The simpler wiring installation methods available to building developers should provide additional cost savings during construction of large building developments. Considerable savings can be realised by installing the meters inside units, compared to the current method of having meters for three floors concentrated on one floor.
Marketing potential. One big benefit of remote metering is as a marketing tool - to obtain an additional share in the hot water market and to stave off the attacks by the gas industry into the high rise hot water and cooking appliances markets.
Prepayment. The meter is designed to display both kWh units and monetary units. This means that a simple prepayment system can be implemented, useful especially in areas where there is high tenancy change, such as university accommodation and holiday apartments.
The total project cost came to $134 126 - about 47% more than conventional metering costs for that particular site. This included all initial specifications, designs, testing, communications software, interfacing to the mainframe billing computer (FACOM) and commissioning tests, much of which will not be required for future installations.
The hardware cost of remote metering for three-phase customers is around $370 extra. When the additional servicing costs for traditional metering are factored in, the remote metering is still more expensive by $160 per customer. Savings in building space and cabling costs have not been presented in this analysis.
As the project evolved, several developments were listed for further consideration. They include:
- An interface unit, to allow smart 3 phase meters (CALMU) to be added to the MeterNet circuit with EMS2600 meters.
- A pulse counting interface to the meter to enable gas and water pulses to be counted and read.
- A version of MeterSoft that supports a single site only, for customers who wish to purchase MeterSoft for their own individual site.
- Billing interfaces in different formats to suit customer requirements, including a format that can be transferred directly into MV90.
- The transfer of MeterSoft to Windows 95 or Windows NT as a migration path for multi-tasking applications.
- The development of complex reading schedules, supported by MeterSoft, to allow multiple reading schedules to be established.
- The modification of MeterSoft to enable the utility to set the load limit for each meter.
- The identification of demand management scenarios.
If the cost savings in meter reading, customer satisfaction, servicing, floor space saving and cabling savings are taken into account, remote metering is an economically viable option for blocks of units such as Admiralty Towers.