Ground fault protection in variable frequency drives

This article explains some aspects of how high resistance grounded (HRG) systems work; examines the various challenges with monitoring ground faults HRGs, and shows how technology can resolve those challenges. Ground faults can be dangerous. A short to ground in a solidly-grounded system creates large currents that can damage equipment and cause a shutdown. A […]

Electrical, insulation and thermal measurements for motors and drives

  Electrical, insulation resistance and thermal measurement are three tests that can troubleshoot motors, drives and associated electrical panels, and prolong their operational lifetime. Most facilities must obtain maximum life out of their motors because they are expensive to replace, in terms of both money and labour. Used together, thermal imagers can detect potential problems […]

Passive and active ARC fault protection in LV switchgear

The traditional methods of passive arc fault protection and the latest active protection options and applications available to industry. Having to wear a “moon suit” against arc flashing when entering LV switch rooms is new to South Africa and many companies who have never experienced arc flash incidents are awaiting developments in the occupational health […]

How to keep VFDs and motors running

  Applied to blowers and pumps, VFDs offer energy savings and, in mechanical applications, allow fine adjustments which are impossible with other methods. Yet they are not simple plug-in-and-forget devices. Variable frequency drives (VFDs) are full of electronics and are susceptible to many problems, from incoming power disturbances to environmental hazards and incorrect use – […]

Arc flash mitigation and arc-resistant switchgear

Application of arc-resistant switchgear to help mitigate arc flash hazards can be a very effective way to enhance safety for electrical workers. Not only the selection of protective device types, but also selecting the settings for adjustable devices is important in the mitigation of arch flashing. Settings must be chosen to protect equipment properly while […]

An improved approach for connecting VSDs and electric motors

  Motor winding insulation can deteriorate quickly and the motor may fail when variable speed drives are connected to motors by long cable lengths. Within the VSD, AC supply voltage is converted into DC by means of a rectifier. DC power contains voltage ripples which are smoothed using filter capacitors. This section of the VSD […]

Electrical, insulation and thermal measurements for motors and drives

  Electrical, insulation resistance and thermal measurement are three tests which can troubleshoot motors, drives and associated electrical panels and prolong their operational lifetime. Used together, thermal imagers can detect potential problems and insulation resistance, while electrical tests can determine the cause. Handheld thermal imagers can collect heat signatures from a range of motors, from […]

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