Electrical safety in low voltage distribution systems up to 1000 V a.c. and 1500 V d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 12: Performance measuring and monitoring devices (PMD)

2Scope / Description

This part of IEC 61557 specifies requirements for combined performance measuring and
monitoring devices that measure and monitor the electrical parameters within electrical
distribution systems. These requirements also define the performance, in single and threephase
a.c. or d.c. systems having rated voltages up to 1 000 V a.c. or up to 1 500 V d.c.
These devices are fixed installed or portable. They are intended to be used indoors and/or
outdoors. This standard is not applicable for:
• electricity metering equipment that complies with IEC 62053-21, IEC 62053-22 and
IEC 62053-23. Nevertheless, uncertainties defined in this standard for active and reactive
energy measurement are derived from those defined in the IEC 62053 standards series.
• simple remote relays or simple monitoring relays.
This standard is intended to be used in conjunction with IEC 61557-1 (unless otherwise
specified), which specifies the general requirements for measuring and monitoring equipment,
as required in IEC 60364-6.
The standard does not include the measurement and monitoring of electrical parameters
defined in Parts 2 to 9 of IEC 61557 or in IEC 62020.
Combined performance measuring and monitoring devices (PMD), as defined in this standard,
give additional safety information, which aids the verification of the installation and enhances
the performance of the distribution systems. For instance, those devices help to check if the
level of harmonics is still compliant with the wiring systems as required in IEC 60364-5-52.
The combined performance measuring and monitoring devices (PMD) for electrical
parameters described in this standard are used for general industrial and commercial
applications. A PMD-A is a specific PMD complying with requirements of IEC 61000-4-30
class A, which may be used in "power quality assessment" applications.
NOTE 1 Generally such types of devices are used in the following applications or for the following general needs:
– energy management inside the installation;
– monitoring and/or measurement of electrical parameters that may be required or usual;
– measurement and/or monitoring of the quality of energy.
NOTE 2 A measuring and monitoring device of electrical parameters usually consists of several functional
modules. All or some of the functional modules are combined in one device. Examples of functional modules are
mentioned below:
– measurement and indication of several electrical parameters simultaneously;
– energy measurement and/or monitoring, and also sometimes compliance with aspects of building regulations;
– alarms functions;
– power quality (harmonics, over/undervoltages, voltage dips and swells, etc).