Common Configurations of Electrical Transformers

A transformer is a device utilized in AC power distribution networks to securely step up or down voltages to cater to the incoming electricity needs of linked equipment. Electrical transformers can accomplish this aim without altering the amount or frequency of power to ensure connected equipment can function reliably. 

An electrical transformer is a stationary device, which means it does not have any continuously moving parts. Consequently, it is easy to maintain and has a long lifecycle. Electrical transformers differ in size from large devices weighing several tons that are commonly utilized in power substations to tiny devices weighing just a few ounces, found in small electrical equipment. 

Electrical transformers have a flexible design and play an essential part in the electrical system. They are used in many types of power distribution applications, including data centers, oil, gas, industrial, water/wastewater, healthcare institutions, schools, and commercial buildings. 

How does It work?

A transformer has multiple secondary coils or windings of insulated wire conductor enclosed around a steel core. Voltage introduced to the primary coil magnetizes this steel core. Then, voltage is induced in the output or secondary coil. The voltage ratio (change of voltage) between these two coils depends on the turn ratio. 

Electrical transformers are of two main types based on the insulation utilized inside the enclosure: liquid-filled and dry type. Here are the basics and common configurations of dry-type electrical transformers. 

What Are Dry-Type Transformers?

Unlike the liquid-filled type, a dry-type transformer does not use liquid to eliminate excess heat to meet temperature classification standards. Instead, the coils inside it are made of dry insulation or gaseous medium. Dry-type electrical transformers are of three types:

Ventilated 

This transformer utilizes fan-assisted or natural circulation via ventilated openings to preserve temperature requirements. 

Non-ventilated 

This electrical transformer has a completely enclosed build, and it is used in applications with atmospheres that contain combustible, corrosive, or conductive materials, which could impact the transformer. It functions by dissipating heat via the enclosure’s surface area. 

Encapsulated 

Also termed potted or compound-filled transformer, encapsulated designs contain windings inside a mix of solid-insulating elements like epoxy, sand, gravel, or resin to assist in heat dissipation. 

Common Kinds Dry-Type Transformers

Common configurations of dry-type electrical transformers include mini-power centers, totally enclosed non-ventilated, general-purpose encapsulated, and general-purpose ventilated. 

Mini-Power Center

A mini-power center includes an interior, encapsulated transformers, and primary and secondary power circuit breakers. This assembly helps to minimize installation complexity, footprint, and cost. 

These transformers have a size range from 3 to 30 kVA, with primary voltages in the range of 380 to 575 V and secondary voltages of 120/208 V (three-phase) and 120/240 V (single-phase). Mini-power centers are suitable for applications that need 120 volts at a remote place, such as temporary power at construction sites, workbenches, and parking lots. 

Totally Enclosed Non-Ventilated

These electrical transformers are ideal for applications in which the environment contains combustible, corrosive, or conductive materials that could damage the transformer, or dust and lint, which might hinder the ventilation pathways. Their enclosure has no openings; therefore, heat is dissipated via the enclosure’s surface area. 

These transformers range from 15 to 300 kVA, with primary voltages in the range of 380 to 575 V and secondary voltages from 120 to 350 V. Totally enclosed non-ventilated transformers function in the temperature rise range of 80°C to 150°C and at a frequency of 50 or 60 Hz. Most enclosures have a NEMA (National Electrical Manufacturers Association) rating of Type 12, 4X, or 3R. 

General Purpose Encapsulated

These electrical transformers are commonly utilized for light industrial and industrial general purposes. They are made of two-winding construction, encapsulated in a mixture of gravel and epoxy-coated sand.

These devices range from 0.05 to 75 kVA, with primary voltages in the range of 380 to 575 V and secondary voltages from 120 to 240 V. Encapsulated transformers function inside a temperature rise range of 80°C to 115°C and at a frequency of 50 or 60 Hz. Most enclosures have a NEMA rating of Type 4X or 3R. 

General Purpose Ventilated

These electrical transformers are leveraged in light industrial and commercial general use applications, with three-phase and single-phase configurations. Their size ranges from 150 to 1,000 kVA, with primary voltages in the range of 380 to 575 V and secondary voltages from 120 to 240 V. 

Ventilated transformers’ coils are wound with 220°C insulation components and copper or aluminum conductors. These transformers function inside a temperature rise range of 80°C to 150°C and at a frequency of 50 or 60 Hz. Most enclosures have a NEMA rating of Type 3R, 2, or 1. 

Remember that critical electrical components, such as electrical transformers, require the expertise of technical professionals. So, consult with a certified electrical professional or leading providers to seek advice on determining your unique requirements and finding the best solutions!