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Measurement for Power availability and reliability

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In order to operate an electrical installation, it is recommended that measurement of the main characteristics of the supply such as voltage, current, frequency, and/or active power are provided as a minimum.

Some electrical phenomena can have an impact on both installation assets and operations within a plant (e.g. unbalance can reduce the life time of motors, dips can stop a process, etc.)

The following table describes the main problems that can occur in a network:

Parameter Measurement Influence on installation energy efficiency Influence on installation performance
Power Factor

(PF or cos phi)

PF Low PF generates additional losses in the installation.

Energy provider is charging penalties to the customer

Cables heating

(cables need to be oversized)

Voltage and current harmonics THDu

THDi

Negative sequence harmonics (u2) are slowing motors down. Harmonics generates extra losses in the installation Early failure of some devices, mainly motors
Permanent or frequent deviations of voltage U Devices may work outside their specified range, and they may over consume, mainly motors Early failure of some devices, mainly motors
Voltage unbalance Uimb Voltage unbalance generates extra losses in motors. Early failure of some devices, mainly motors
Dips and interruptions Udip

Uint

--- Process interruption with financial impacts
Frequency f --- Rotating machines may change their speed according to frequency
Flicker or RVC Pst

RVC

--- These phenomena can generate disturbing phenomena on lighting

Fig. S4Main problems that can occur in an electrical network, and their potential consequences

The main standards are specified below:

Installation needs /standard Measuring methods standard Product standard
Voltage, current and frequency indication --- Analog meters

Logo IEC.png IEC 60051
Direct acting indicating analog electrical measuring instruments
Electrical Distribution Monitoring --- PMD (Power Meters)

Logo IEC.png IEC 61557-12
Power Metering and Monitoring devices (PMD)

Logo IEC.png IEC 61000-4-30
Testing and measuring techniques – Power quality measurement methods
PMD (Power Meters) with class A or S methods

Logo IEC.png IEC 61557-12
Power Metering and Monitoring devices (PMD)
and
Logo IEC.pngIEC 62586-2Logo New.png
Power quality measurement in power supply systems - Functional tests and uncertainty requirements
(Compliance to IEC 62586-2 means compliance to IEC 61000-4-30)

Fig. S5Standards for power availability and reliability

Fig. S6Examples of products compliant with IEC 61557-12, for Electrical Distribution Monitoring