A Quick look at Transformers

A transformer is an electromagnetic devices which transfers electrical energy through electromagnetic induction. It steps a voltage or current up to a higher voltage level or down to a lower voltage level. Transformers operate on alternating current. Some specialized transformers can also limit electrical noise transfer or match circuit impedances.

Transformers enable the use of different kinds equipment with various voltage requirements. For example, a system of transformers can enable the use of 25kV, 5kV and 120V equipment at a single facility. A light may require 120V to operate, while a motor may need 600V. A very large and specialized motor may require 5kV whereas the control transformer within a motor control unit may only require 120V. Some specialized transformers can also limit electrical noise transfer or match circuit impedances.

In a single phase transformer, alternating current is applied to its primary coil, which causes magnetic flux to flow in the transformer core. In turn, an alternating current is then induced in its secondary coil. The induced current is dependent on the number of turns in the primary and secondary coils. Transformer cores are typically constructed with iron or steel.


Transformer Coils

Three phase transformers are similar in function and construction to single phase transformers. However, transformers used with three phase power require three interconnected coils in both the primary and secondary, and connected in either a wye or delta arrangement.


Control power transformers are used in control circuits such as motor controls. They are utilized to provide power to motor control circuits. For example, a control transformer may step down 600V from a power circuit feeding a motor to 120V, which can be utilized by control circuits in the motor starter unit.


Transformers come in various shapes and sizes. This is one type of transformer.


This is also a transformer. However this one is likely operating at a lower voltage than the previous one.

Encapsulated or Ventilated

Encapsulated transformers are intended for use in wet, dirty, or dusty locations. The core and coil are embedded in resin and all components are totally enclosed in a sealed, non-ventilated enclosure.

Ventilated transformers provide cooling to the windings with natural airflow. Openings are designed to prevent external contact and can be used for indoor and outdoor applications.

Transformers intended for outdoor applications can be specified with a NEMA 3R/4/4X enclosure rating to help protect against environmental conditions or corrosive chemicals.

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