5.1.1 Modular approach

When establishing the performance requirements and when performing tests on smart meters, breaking these systems down into modules has the following advantages:

• a smart metering system in many cases already comprises a number of modules, the configuration of which can easily differ;

• for some tests it is almost impossible to expose the smart metering system as a whole;

• when applying a modular approach the focus of the evaluation performance can be restricted to only those modules which have an influence on the legal metrology results.

A disadvantage is:

• practical results concerning the response of the system as a whole are not available prior to the installation.

Performing tests on a system as a whole, however, would only be useful for testing the mutual influence between devices installed at exactly the same distance from and orientation to each other.

While these geometric parameters tend to be rather random, tests on mutual interference will be very complex. A subdivision into modules combined with signal simulation is therefore more appropriate.

• Identifiable parts (instruments, devices or modules; whatever is applicable)

  To arrive at an overview for the purpose of setting requirements and performing tests, a (smart) metering system can be considered as consisting of a combination of identifiable parts.

  For each of these parts the model below may be applied. Each part, stand-alone or as part of a (measurement) system, can be considered as a black box with a number of input and output ports.

• Definition of an input or output port

  For the purpose of this Report, an input or output port of a device is considered as being each physical channel through which a connection is or can be made between the electronic circuits in this device and:

  • another device; or

  • a network; or

  • the electromagnetic environment.

  Such a connection may be established by making use of a physical product/medium (for example a cable) or a physical phenomenon (wireless).

• Kinds of ports

  A measurement device/module may comprise several ports having identical or different functions. Such physical ports may be used for different purposes which may be sequential or simultaneous and which make use of one and the same connection.

  For example, distinction between the following kinds of ports may be made:

  • (power) supply port;

  • measurand input and output port;

  • data transmission port;

  • signaling and switching ports;

  • enclosure port; and

  • operator panel.

  

• Multi-function ports

  An example in which a port is used for more than one purpose is the connection of an electrical energy meter to the mains power supply. In this case the wires are used for:

  • transmission of the electrical energy;

  • electrical energy supply to the energy meter;

  • data transmission line.

  Another subdivision could be made for data transmission, and one could even distinguish between data transport and pulses mainly for switching purposes. The data transmission can include the electrical energy meter measurement data.

  Each of the input and output ports can potentially influence the measurement data.

  Each type of port, on the one hand, has to withstand improper intervention and on the other hand should not emit or produce a phenomenon to such a level that it leads to a disturbance on one of the other ports.

  When observing the different ports, the influence quantities listed below should be taken into account.

  1 Power supply port

  The device will need to withstand or filter out the following disturbances from the power supply port:

  • mains voltage interruptions;

  • mains voltage variations;

  • mains voltage surges and bursts;

  • all communication signals;

  • induced radio frequency currents (antenna behavior).

  2 Measurand input port (analogue)

  The device will need to withstand or filter out the following potential disturbance from the measurand input port:

  • induced radio frequency currents (antenna behavior).

  3 Enclosure port

  The device will need to withstand or filter out the following potential disturbances from the enclosure port:

  • temperature/humidity fluctuations;

  • electrostatic discharges;

  • induced currents from radio frequency sources (antenna behavior);

  • induced currents from power frequency sources including harmonics (near field coupling).

  4 Data transmission port

  The device will need to withstand or filter out the following potential disturbances from the data transmission port:

  • data transmission line surges and bursts;

  • out of band communication signals (signals for which the port is neither specified nor reserved);

  • out of band induced radio frequency currents (signals for which the port is neither specified nor reserved).

  5 Operator port

  The device will need to withstand or filter out the following potential disturbances from the operator port:

  • electrostatic discharges;

  • induced currents from radio frequency sources (antenna behavior);

  • induced currents from power frequency sources including harmonics (near field coupling).