Remanufactured & Refurbished Transformers

RESA Power offers refurbished and remanufactured transformers at a cost-effective price, providing the same performance as new units from original equipment manufacturers. Our remanufactured transformers are typically 60% to 70% cheaper than new ones. With RESA Power Service’s remanufacturing program, you can expect quick turnarounds and competitive prices. We customize transformer lead times and delivery schedules to meet your specific needs and site requirements, often surpassing factory lead times by weeks or months.

With transformer rebuilding, our engineers can extend the lifespan and maximize the performance of your transformers. We stock a wide range of components and fully built remanufactured transformers that can be certified to your specifications. Let RESA Power help optimize your equipment’s performance and longevity- contact us today to get a quote for all your transformer remanufacturing needs.

Transformer Remanufacturing




Transformers go through a rigorous process to ensure the equipment is high quality and performs its design functions safely. RESA Power Service revitalizes transformers quickly, offering sustainability for your employees. The decreased delivery times mean you won’t have to wait long for a completely rebuilt pre-owned transformer. Reduce, reuse, recycle!


RESA Power is an established supply leader known for providing high-quality components assisting clients with the life extension of electrical equipment at a reasonable price. Click view products online to view our large inventory of electrical equipment now or at your convenience. You can also request a quote from RESA Power directly and speak with a professional consultant in our sales team that will gladly help you find that elusive piece of equipment to fit your specific needs! Our high-quality products come from a wide variety of recognizable major manufacturers. That same brand recognition will give your clients peace of mind knowing that RESA Power’s qualified technicians have restored it to its original equipment manufacturer’s specifications.


Our four distribution and manufacturing centers across the United States provide high-quality service and support to every major metropolitan area.

Our reliable remanufacturing service includes:

Electrical testing per IEEE and NETA standards
Testing includes transformer turns ratio (TTR), insulation resistance, winding resistance, power factor, excitation, and over potential – Hi Pot.
Testing is performed on equipment prior to cleaning or maintenance work
The results of the testing serve as a baseline report for further analysis and comparison.
Top cover and insulating fluid are removed.
Internal inspection is conducted to provide an assessment of the condition of the equipment.
Busing is cleaned and removed.
Gaskets are replaced on all components.
Bushings are cleaned, inspected and paddles are re-tinned
Windings are inspected, cleaned, and flushed.
All electrical connections are verified mechanically and via resistance testing.
Insulating fluids are either reclaimed or replaced and vacuum backfilled into the tank.
Top cover is reinstalled.
24-hour pressure testing is performed at 5-6 psi (not to exceed tank rating).
Paint prepping is executed including sanding, bodywork, and rust removal.
All transformers are painted with a urethane or epoxy two-part topcoat.


All of RESA Power’s Service professionals conduct electrical tests following the standards of NETA, the worldwide expert in electrical power systems and equipment assessment. All equipment is fully tested and warranted.

Electrical Tests Include:

The Insulation Resistance Test has been a trusted method in use for many years to determine the strength and moisture content of solid insulation. By measuring leakage current, this direct current (DC) test provides valuable information about the insulation’s dielectric properties.
The Polarization Index (PI) is a crucial indicator of the health of motor insulation. When solid insulation comes into contact with moisture, the PI value drops – a lower PI value indicates a more deteriorated condition. Ideally, the ratio should be at least 2.0, with values closer to 1.0 indicating poor insulation health. Achieving a ratio between 1.0 to 2.0 is considered marginal, and it’s important to identify the accumulation of contaminants using this typical ratio.
Testing Insulation Quality with the Dielectric Absorption Test – Ensure that your insulation is top-notch by monitoring its resistance levels over time. One key metric for this is the Dielectric Absorption Ratio (DAR). It measures the ratio of 30-second and 60-second insulation resistance values, indicating the durability of your insulation. The grading of DAR is consistent with the Polarization Index (PI), making it a useful tool for assessing insulation quality.
The Winding Resistance DC test is essential to verify proper wiring connections and tight connections in your electrical circuits. This test also serves as a foundation for detecting any potential damage. In a three-phase setup, each phase’s winding resistance is compared against the other two phases. A balanced comparison is ideal, with gradual increases or decreases as the tap positions are adjusted.
Transformer Turns Ratio: this ratio assures there are no open connections, no shorted or open turns in the windings, or incorrect polarity connections, and verifies the voltage ratio of the transformer in each tap.
The Power Factor Insulation Test is an effective maintenance technique that measures both solid and liquid insulation losses using alternating current (AC). By analyzing the proportion of power used to the total product of applied voltage and current, it detects power loss in the insulation. To ensure the proper functioning of transformers, it is recommended to measure the preferred power factors of new or properly dried equipment and use the obtained baseline for subsequent readings. This enables monitoring changes in internal losses and identifying potential issues early on.
Excitation Test: this AC test checks for abnormal core conditions such as deterioration of the insulation layers at the core laminations, loose core clamps, multiple core grounds, shorts from the core to the tank, disarrangement or lamination slippage are measured as core losses, and compared to original factory test results. Note: on 3 phase transformers the excitation current is typically similar for two phases but notably less for the third phase which is wound on the center leg of the core assembly.
With Over Potential Testing (Hi Pot), you can stress the solid insulation in a transformer like never before. By applying a higher voltage to the transformer’s windings than their ratings, this test (AC or DC) can determine its capacity and level of testing desired. With 3 levels of Hi Pot testing – Factory, Acceptance, and Maintenance – as described in NETA and IEEE publications, you can trust that your equipment will be up to par. We carefully apply voltage in gradual steps until we reach the desired level, monitoring leakage currents along the way.
Auxiliary and Functional Checks: will ensure that the instrumentation and accessories are in proper working order and function as desired (fans, gauges, switches, and relays).


RESA Power’s specialties are not limited to selling power transformers! We are transformer experts offering service and maintenance after the sale, too! Special services include refurbishing, rebuilding, and repairing transformers; oil servicing, purification, and reclamation; painting/shot blasting; testing; and customizing to your needs in this dynamic industry. Services and maintenance are unlimited and include step voltage regulators, reclosers, switches, breakers, and capacitors.

With the advent of Western Utilities Transformer Service, a RESA Power company, our transformer services team has provided electrical solutions to thousands of companies throughout the United States and Canada for over 35 years. Since 1985 we have provided quality services and repair of electrical apparatus and systems with a commitment to detail and customer satisfaction. This commitment to quality and service has fostered the development of strong relationships with both domestic and foreign leading manufacturers of electrical power and distribution equipment.

Western Utilities Transformer Service is a complete service center and original equipment manufacturers’ warranty service centrally located in central California. The service center is supported by factory-trained service technicians, NETA-certified testing centers, insulating fluids laboratories, and component distribution centers throughout the state and the continent. Our combined efforts of providing support to the OEM’s for warranty repairs, installations, and startups for the contractors and ongoing repairs and maintenance to the end-users has established RESA Power as the “go-to source” for all of your power needs.


RESA Power has a wide variety of offerings to fill your transformer requirements. Pad mounted, pole mounted, vault, or substation styles of transformers and related equipment are included in the array of equipment sold and serviced by RESA Power. Moreover, our Service Center provides expert in-shop testing, modernization, and upgrade services for transformers and other substation equipment. We provide 24/7 emergency services for most domestic and foreign OEM products, liquid filled or dry, substation type or pad mounted, power or distribution, pole mounted or underground transformers, and electrical equipment.


RESA Power offers warranties that cover products sold for either one, two, or three years. See our terms of sale for warranty details as needed. Reduce your installation lead time with our reliable remanufactured transformers. Save time and money by contacting RESA Power today!