Power Monitoring Equipment To Correct Drive-generated Harmonics

By Author: SamJacob Thomas
Total Articles: 40
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An essential component for most machines is speed and force. Drives that carry out this function come in the list of the important components of the same, especially they are useful when the speeds need to be controlled and adapted as per the need of the product. This is where adjustable speed drives ASDs come into the picture. There are two main types of ASDs:

SCR convertor drives

The Silicon Controlled Rectifiers or SCR drives are popularly known as six step drives. These convert the DC link voltage by gating the flow of the current of the section of the applied sine wave, plus, it also switches off at the zero-crossing points. Unlike diodes, SCRs require control circuits for gate firing. These converters affect the power quality in three main ways.

First, their commutation may what is in effect a momentary short circuit that tends to collapse the line voltage. Secondly, as the drive speed goes down, the displacement power factor declines as well. And of course, the harmonic currents, typically the 5th and 7th, are generated by VSI drives. With an effective power recorder ...
... this may be monitored and look for an effective control action.

PWM drives

PWM drive requires no switching control circuitry. This is extremely popular thanks to the continued development of fast-switching, efficient Insulated Gate Bipolar Transistors used in the inverter section of the drive. For the diode converter, the main PQ issue is harmonics.

These drives are essential but it may create harmonics in the process of its operations.Higher harmonics creates large issues including the damage to the insulation of cable and motors and result in a premature failure.With the help of effective power monitoring equipment this may be monitored and implement effective control and mitigation system.

To solve or mitigate harmonic issues, you need to start with the monitoring of the drive with a quality three phase or single phase voltage recorder.The solution to mitigate Harmonics is by installing Harmonic filters. These filters are installedlocally on the line side of thedrive.

You must keep in mind that harmonics mitigation andtraditional DPF correction may be addressed as an issue of single system.