Download Software Guide (Measuring Instruments Directive 2004

WELMEC WG7
10.3
Software Guide
WELMEC 7.2, Issue 5
Active Electrical Energy Meters
10.3.1 Specific regulations, standards and other normative documents
Member states may – in accordance with MID Article 2 – prescribe Active electrical
energy meters in residential, commercial and light industrial use to be subject to
regulations in MID. The specific requirements of this chapter are based on Annex MI003 only.
OIML recommendations or IEC standards have not been taken into consideration.
10.3.2 Technical description
Active electrical energy meters take voltages and currents measurements as inputs,
derive the active electrical power from them, and integrate this with respect to time to
give the active electrical energy.
10.3.2.1
Hardware Configuration
Active electrical energy meters typically are realised as built-for purpose devices
(Type P in this document). They may have one or more inputs and may be used in
combination with external instrument transformers.
10.3.2.2
Software Configuration
This is specific to each manufacturer but would normally be expected to follow the
recommendations given in the main body of this guide.
10.3.2.3
Measuring Principle
Active electrical energy meters continually cumulate the energy consumed in a
circuit. The cumulative energy value is displayed at the instrument. Various
transducer and multiplier principles are employed.
The energy measurement may not be repeated.
10.3.2.4
Fault Detection and Reaction
The requirement MI-003, 4.3.1 deals with electromagnetic disturbances. There is a
need to interpret this requirement for software controlled instruments because
detection of a disturbance and recovery is only possible by co-operation of specific
hardware parts and specific software. From the software point of view it makes on
the other hand no difference what the reason of a disturbance was (electromagnetic,
electrical, mechanical etc): the recovery procedures are all the same.
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