Iec Harmonic Standards - Danfoss VLT AutomationDrive FC 302 Installation Manual

Introduction

1.6.4 IEC Harmonic Standards

The mains voltage is rarely a uniform sinusoidal voltage with constant amplitude and frequency because loads that draw
non-sinusoidal currents from the mains have non-linear characteristics.
Harmonics and voltage fluctuations are 2 forms of low-frequency mains interference. They have a different appearance at
their origin than at any other point in the mains system when a load is connected. So, a range of influences must be
determined collectively when assessing the effects of mains interference. These influences include the mains feed, structure,
and loads.
Mains interference can cause the following:
Undervoltage warnings
•
Incorrect voltage measurements due to distortion of the sinusoidal mains voltage.
•
Cause incorrect power measurements because only RMS-true measuring takes harmonic content into account.
Higher functional losses
•
Harmonics reduce the active power, apparent power, and reactive power.
•
Distort electrical loads resulting in audible interference in other devices, or in worst case, even destruction.
•
Shorten the lifetime of devices as a result of heating.
In most of Europe, the basis for the objective assessment of the quality of mains power is the Electromagnetic Compatibility
of Devices Act (EMVG). Compliance with these regulations ensures that all devices and networks connected to electrical
distribution systems fulfil their intended purpose without generating problems.
Standard
EN 61000-2-2, EN 61000-2-4, EN 50160
EN 61000-3-2, 61000-3-12
EN 50178
Table 1.6 EN Design Standards for Mains Power Quality
There are 2 European standards that address harmonics in the frequency range from 0 Hz to 9 kHz:
EN 61000-2-2 (Compatibility Levels for Low-Frequency Conducted Disturbances and Signalling in Public Low-Voltage Power
Supply Systems) states the requirements for compatibility levels for PCC (point of common coupling) of low-voltage AC
systems on a public supply network. Limits are specified only for harmonic voltage and total harmonic distortion of the
voltage. EN 61000-2-2 does not define limits for harmonic currents. In situations where the total harmonic distortion
THD(V)=8%, PCC limits are identical to those limits specified in the EN 61000-2-4 Class 2.
EN 61000-2-4 (Compatibility Levels for Low-Frequency Conducted Disturbances and Signalling in Industrial Plants) states the
requirements for compatibility levels in industrial and private networks. The standard further defines the following 3 classes
of electromagnetic environments:
•
Class 1 relates to compatibility levels that are less than the public supply network, which affects equipment
sensitive to disturbances (lab equipment, some automation equipment, and certain protection devices).
•
Class 2 relates to compatibility levels that are equal to the public supply network. The class applies to PCCs on the
public supply network and to IPCs (internal points of coupling) on industrial or other private supply networks. Any
equipment designed for operation on a public supply network is allowed in this class.
MG37A322
Installation Manual
Definition
Define the mains voltage limits required for public and industrial power grids.
Regulate mains interference generated by connected devices in lower current products.
Monitors electronic equipment for use in power installations.
Danfoss A/S © Rev. 04/2015 All rights reserved.
1 1
17