The increasing number of distributed energy resources, non-conventional loads and non-linear elements in the power grid negatively impact on its power quality (PQ). Regulating standards such as EN 50160 or IEC TS 62749 force utilities to prove their PQ conformity. As a consequence, more and more power quality instruments (PQI) are installed in the electrical network and at connection points which should be tested periodically.
Other than with protection relays, there are no commonly established rules or procedures for installation and routine testing or calibration. Furthermore, there is little experience and a lack of awareness for PQ especially in small utilities, industry and at end-use customers. Therefore, malfunctioning or reduced accuracy can remain unnoticed, although they may have significant monetary impact. This paper describes how to test a PQI as well as appropriate procedures for type, acceptance and routine testing.