All Transformers are Not Created Equal – How to Tell Which One is Best for You

A transformer is an essential component of any electrical system.  A transformer transfers electricity from one circuit to another while adjusting the voltage level.  Transformers are used in a wide array of applications including power transmission and distribution for electrical facilities.  The operating principle of a transformer is based on Faraday’s Law of Electromagnetic Induction.

General Purpose Applications

The vast majority of transformers are two-winding units, which consist of an input winding and an output winding.  Step-up transformers can change the voltage of a generator from 13.8kV to 72kV for use on a local distribution grid.  Step-down units are responsible for changing the higher distribution voltage down to something more appropriate for a small industrial or commercial building.  But the world of transformers is much larger than those two applications and come with varying levels of complexity.

Specialty Transformers for Heavy Industry

Transformers associated with complex electrical power systems can include three-winding or multi-winding configurations with extended overloading and the ability to absorb induced harmonics.  What sets heavy-duty transformers apart from general-purpose equipment is their ability to handle heavy loads.  An electrical arc furnace transformer has some of the heaviest duties imposed on it; other types can operate on the basis of direct flux regulation or booster regulation.  Rectifier transformers dedicated to large industrial drive systems or traction power systems require specific harmonic absorption capabilities when supplying 12-pulse or 18-pulse DC output rectifiers. These transformers can have two or three secondary windings.  A general-purpose transformer design is not suitable for such applications and will not last long under such rigorous conditions.

Selecting the Most Appropriate Transformer for Your Application

All transformers have one thing in common – what goes on in one winding also affects what goes on in the neighboring windings.  Proper modeling of multi-winding transformers is essential to ensure a proper, safe, and reliable operation.  This includes consideration of short circuit impedances, the mutual impedance between windings, hysteresis performance, coupling factors, and effective commutating reactance.  You must obtain these parameters from a reputable source or have a subject matter expert empirically derive them, in order to construct an accurate model and simulate power system performance.  Commercially available engineering software tools will not handle these functions effectively.  A proper transformer analysis will allow a drive manufacturer to apply a heavy propulsion system or a transit authority to operate a rectifier-transformer for traction power.

To ensure the effective operation of your complex electrical power system, you should analyze it and specify the appropriate transformer.  We make specific recommendations to improve reliability which can save you money.  If you would like to know more, feel free to call us at (240) 582-3900 or email us at info@helioselectric.net.

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