IEC 61921:2017 pdf download

IEC 61921:2017 pdf download.Power capacitors – Low-voltage power factor correction banks
1 Scope
This International Standard is applicable to low-voltage AC shunt capacitor banks intended to be used for power factor correction purposes, possibly equipped with a built-in switchgear and controlgear apparatus capable of connecting to or disconnecting from the mains part(s) of the bank with the aim to correct its power factor. Low-voltage power factor correction banks if not otherwise indicated hereinafter and where applicable comply with the requirements of IEC 61 439-1 and IEC 61 439-2.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 61 439-1 :201 1 , Low-voltage switchgear and controlgear assemblies – Part 1: General rules IEC 61 439-2:201 1 , Low-voltage switchgear and controlgear assemblies – Part 2: Power switchgear and controlgear assemblies IEC 60831 -1 :201 4, Shunt power capacitors of the self-healing type for AC systems having a rated voltage up to and including 1 000 V – Part 1: General – Performance, testing and rating – Safety requirements – Guide for installation and operation IEC 60931 -1 :1 996, Shunt power capacitors of the non-self-healing type for AC systems having a rated voltage up to and including 1000 V – Part 1: General – Performance, testing and rating – Safety requirements – Guide for installation and operation IEC 61 642:1 997, Industrial AC networks affected by harmonics – Application of filters and shunt capacitors
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61 439-1 , IEC 61 439-2, IEC 60831 -1 and IEC 60931 -1 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: • IEC Electropedia: available at http://www.electropedia.org/ Note 1 to entry: The capacitor bank can be fixed, manually switched or automatically controlled through the use of a power factor controller. Note 2 to entry: The components of switchgear and controlgear of the automatic bank may be electromechanical or electronic. 3.2 step of capacitor bank combination of one or more capacitor units switched together through a single switch with possible detuned reactors, connecting wires, and associated switchgear and controlgear apparatus 3.3 automatic reactive power controller device designed to calculate the reactive power absorbed by the load connected to the power line and to control the switching on and off of the steps of the automatic bank, in order to compensate for the reactive power Note 1 to entry: The reactive power is normally calculated at the fundamental frequency. Note 2 to entry: The controller may be “built-in” or “free-standing”. Note 3 to entry: The controller generally performs functions of measurement / monitoring of power, controlling (of capacitor steps) and protection (of capacitor bank). 3.4 transient inrush current I t transient overcurrent of high amplitude and frequency that may occur when a capacitor is switched on, the amplitude and frequency being determined by factors such as the short- circuit impedance of the supply, the amount of energized capacitance switched in parallel and the instant of the switching 3.5 rated reactive power Q N (of a capacitor bank) total reactive power of a capacitor bank at the rated frequency and voltage, calculated by the total impedance of the bank including reactors, if any 3.6 maximum permissible current value of current declared by the manufacturer which can be present continuously in the capacitor bank, used for installation and protection settings