New & Used Electrical Power Transformers

new used transformersESU, Inc. has a large inventory of new and used buck boost and auto transformers  If you require I phase 3 Phase 208/240, 208 to 240, 208 to 480, 120 to 240 or other voltages we usually have the transformer in stock.

We usually stock Acme, Westinghouse, Cutler Hammer, ITE Siemens, FPE  Federal Pacific, Square D, General Electric and Zinsco products.

We also carry a wide variety of commercial power transformers. Low Voltage Distribution General Purpose Commercial Transformers for all of San Diego. ESU offers a wide selection of electrical products that include buck-boost transformers, low voltage lighting transformers, mini power centers, and autotransformers.

All our recycled equipment has been tested and has our guarantee.

ESU is your trusted partner in electrical supplies with over 40 years of industry expertise! As a seasoned leader, we take pride in our extensive inventory of new, surplus, and recycled electrical power transformers, catering to both commercial and residential markets. Our commitment to sustainability and quality ensures that our customers have access to a diverse range of transformers that meet the highest industry standards. With a legacy built on reliability and customer satisfaction, ESU remains at the forefront of the electrical supplies sector, providing innovative solutions to power the present and future. Explore our vast inventory and experience the ESU difference – where experience meets excellence in electrical supply solutions.

Electrical Supplies Unlimited, or ESU Inc, is your trusted partner in the electrical supply industry for over four decades. With a rich legacy spanning 40 years, ESU has been a cornerstone for electricians in San Diego, providing top-notch electrical products and unmatched expertise. Our commitment to quality and reliability has made us a go-to resource for professionals seeking a comprehensive range of electrical supplies.

At ESU, we understand the dynamic needs of electricians, and our extensive experience allows us to cater to the unique requirements of the San Diego market. As a testament to our dedication, ESU is not only a leading supplier but also a reliable destination for those looking to sell excess electrical transformer inventory. We pride ourselves on fostering lasting relationships with our customers, ensuring they have access to cutting-edge products and services. Trust ESU Inc for all your electrical supply needs – where experience meets excellence, and your satisfaction is our priority.

An electrical transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF), or "voltage", in the secondary winding. This effect is called mutual induction


A single phase transformer is a type of transformer which operates on single-phase power. 

Single-phase transformers are usually used for single special applications or voltages. For instance, equipment that specifically requires 240 volts single-phase where the service voltage is 120/208 volts. For an application like this, it is common to only provide a single-phase transformer for the equipment because there won’t be a different electrical loads served by it. 

Phase imbalances can occur when a single-phase transformer is used for general distribution while using a three-phase utility. If a property is served by single-phase and a transformer is used (e.g., for isolation) then a single-phase transformer would be appropriate.

Three-phase transformers are a type of transformers that are used to change voltages of electrical systems with three phases. There are different types of configurations for three phase transformers: star-star, delta-delta, star-delta, and delta-star. 

Core-type transformers act as a single-core, three-phase transformers where each phase is magnetically coupled to each other.