In September 2002, the Costa Rican Institute of Electricity (Instituto Costarricense de Electricidad, ICE) initiated its first rural automatic meter reading (AMR) project along the north coastal zone of the Caribbean Sea.

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The traditional manner of reading electricity meters, i.e. manually, has a significant economic impact on the business of the distribution and commercialisation of electricity worldwide. For this reason, the use of AMR systems continues to increase, as it not only eliminates the manual process of meter reading but also has other value added aspects.

An AMR solution

Some years ago, the electrical department of ICE started a review process of the technological options it had for the automation of the meter reading process. It was decided that this process would be applied in the remote areas which are difficult to access and thus the monthly meter reading task is costly to undertake.

pg 62.2The areas selected for the implementation of this project were all situated along the north coast of the Caribbean Sea. Besides being remote they are also surrounded by rivers, lagoons and canals, and are thus accessible only by boat or on foot. The region is supplied by a single phase circuit (19.9 kV) 90 km in length, and therefore PLC AMR technology was chosen, as it allows the meter data to be transmitted to a concentrator by the electrical system.

The start of the project

At the start of the project, a series of visits were carried out in the region in order to evaluate the conditions of the electricity network and its services. This was necessary in order to guarantee that the right conditions existed for the replacement of the existing meters with new solid state meters with an AMR module.

The problems found in the area that could affect the correct functioning of the system and its equipment were:

  • Abundant rain almost all year round. This region has some of the highest rainfall in the country, between 5,000 to 6,000 mm per year. However, there are two types of rainfall experienced – the sudden downpour of short duration that is the most frequent, and the characteristic storms of the Caribbean that can last up to 15 days.
  • The high relative humidity, which is exacerbated by the abrupt changes of climate that are generated by the trade winds from the north and northwest, or by the formation of tropical storms or hurricanes.

As a result the meters absorb moisture from the copious rain and the high relative humidity. Coupled with the effect of salt off the sea, a high level of corrosion is experienced in the project area, which in turn affects the materials and equipment used in the installation of the electricity services.

Solutions

The following measures were put into effect to address these problems:

  • Substitution of 95% of the meter connection boxes or sockets, as the materials with which the solid state single phase meters (2S form) are made are vulnerable to high temperatures and can cause shorting between the connection blades and the mouth of the socket. Moreover these shorts can affect the PLC communication.
  • Overhauling the electricity services, including replacing components, compression connectors and earthing systems, because of their potential for corrosion.
  • Recommendations to clients to improve blades, boxes, posts, etc.
  • Sealing of the sockets with expandable polyurethane foam, in order to reduce the penetration of moisture, thus eliminating or delaying corrosion.
  • Sealing of the sockets with 1¼ inch PVC stoppers.
  • Monitoring the development of corrosion through periodic inspections to determine the permeability of the sealing of the connection boxes.

The Tortuguero automation project

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The AMR/PLC system consists of the meters and the concentrator. Each solid state meter has a PLC transmitter module with a unique frequency incorporated. The concentrator, installed at the Leesville substation 90 km away, recognises the registers of all the meters based on their frequency of transmission. Subsequently this information can be accessed via modem for billing or management and maintenance of the network.

The system is unidirectional, which means that data cannot be sent to the transmitters nor can they be remotely reprogrammed. The solid state electrical meters used in this project are C1S Centron from Itron with an AMR PLC module from Hunt Technologies, as also are the concentrator and the software. The project registers 850 electricity connections in the areas of Colorado and Tortuguero. These services have had automatic reading from November 2004, and since that time the system has been working correctly.

Results

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The AMR system eliminates the process of manual reading. When using solid state meters there is more efficient reading, due to the precision of the equipment. In addition the meters have the capacity to detect and register very low loads. Errors and estimates when reading the meters are also now eliminated, since the human error factor of manual reading is eliminated. The system provides information about the residential customers’ behaviours and enables the building of customer profiles on a daily, rather than monthly, basis.

The detection of energy theft is also possible, as it can be readily established if a customer disconnects his meter in order to steal energy. The system also takes voltage samples and counts the outlets of the system in order to calculate levels of service quality. It can also establish the load conditions of the transformers. Finally metering technical personnel can be reassigned to other maintenance tasks on the network.

Recommendations

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Personnel of the electricity agency who manage the system must be given training, as it is important for them to understand its technical aspects. It is also important for them to have a good understanding of the software, in order to be able to access additional information on the consumption patterns of customers and the possible detection of illegal uses of energy, and thereby provide a quality service. It should be noted that remote metering needs fewer technician visits to the metering points.

This might allow illegal connections to be implemented or give rise to problems of preventive maintenance. Therefore, it is recommended that inspections should be carried out every three months to a representative sample of customers, in order to validate the data in the system against that in the meters. The software of this system has many tools such as the reading of the concentrator, diagnosis, reports and others. However, it is not totally adapted to the billing system of ICE, which has its own peculiarities.

To solve this, a software application was developed to act as an interface between the Turtleware and the ICE billing system. This application reads the databases and carries out a validation so that they can be incorporated into the billing system. This first AMR PLC project sets a very important precedent not only for ICE but also for other electricity distributors.

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Also, it opens the way for the exploration of AMR options in the water service. After the full implementation of this project, additional AMR PLC projects will be implemented in other rural areas of Costa Rica. Also, an AMR radio frequency project with some 1,500 points will be piloted in one city. ICE is open to the use of AMR technologies, mainly because of the increasing price of oil and the fact that these types of project are becoming more cost effective and profitable. Another important factor is that many of the regions where ICE provides electricity services are suitable for using an AMR system.