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Electrical Transformers



Purchasing Reconditioned Electrical Equipment

Debunking the myths about tested and refurbished equipment BY RISHI SUDAN, RS Electrical Supply Extending the lifecycle of capital equipment such as 15-kilovolt circuit breakers, switchgear, and transformers through testing and reconditioning saves time and money by cutting down on new equipment...

Transformer Core Grounds

Transformer core grounds: a different path to maintaining insulation systems BY JAMES WHITE, Shermco Industries, Inc. Power transformers are usually supplied with a ground from the core of the transformer to the tank (earth/ground). Smaller, dry-type transformers may not have this ground, but it...

Electrical Transformers

Transformer Diagnostic Testing

Transformer diagnostic testing: standards to diagnose equipment with Sweep Frequency Response analysis

BY VOLNEY NARANJO, Megger

Sweep Frequency Response Analysis (SFRA) has become a powerful tool in advanced power transformer assessments and probably one of the main and first tools used to diagnose troubled transformers or as a regular maintenance test. In addition to being able to detect problems related to the mechanical or electrical integrity of the transformer, the results can be compared to...

Related Articles


Transformer Core Grounds

Transformer core grounds: a different path to maintaining insulation systems BY JAMES WHITE, Shermco Industries, Inc. Power transformers are usually supplied with a ground from the core of the transformer to the tank (earth/ground). Smaller, dry-type transformers may not have this ground, but it...

How to Improve Transformer Protection

Using symmetrical components for fault discrimination in differential protection BY IMRAN RIZVI, ABB Inc. Classical differential protection schemes are subject to ghost differential currents due to current transformer (CT) saturation and magnetization currents. Several methods are used to counter...

Grounding Transformers Explained

By R. W. Hurst, Editor Grounding transformers are used to provide a path to ground for unbalanced load current and for fault currents on systems where a suitable ground is otherwise not available. Grounding transformers are normally constructed with one of the two configurations: Zig-Zag (Zn) with...


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