Transformer Service Inc.
Transformer Service Inc.

Electrical Services

Electrical test and maintenance of transformers, relays, and circuit breakers

Transformer Service, Inc. has been a leader in improving transformer and switchgear reliability and performance since 1952. TSI has developed preventive maintenance strategies that identify and cure potential problems before they affect operation or longevity.

The cornerstones of TSI’s preventive program are oil sampling, electrical tests and visual inspection. Together, these three methods provide the information to analyze the condition of your transformer and switchgear and to determine the steps needed to assure reliability and top performance.

Electrical Testing

Electrical tests accurately measure these important values:

  • Insulating value of insulation (DC Megger)
  • Resistive and capacitive loss (DC Hipot)
  • Power Factor (tests of transformers and bushings)
  • Relationship of primary and secondary voltages (TTR)
  • Trip levels and accuracy of relays and low, medium, and high voltage circuit breakers

Test results are compared to manufacturers’ specifications and/or performance standards set by NETA, IEEE, and NEMA, and establish a baseline for comparison with future tests. Repairs or calibration needed to bring equipment into specification can be easily identified, and post-repair testing assures that proper corrective action has been taken.

In many cases, testing identifies the need for simple repairs and adjustments that preclude costly repairs and downtime in the future.

Tests Performed

The suite of tests includes the following:

  • Dielectric absorption
  • Insulation resistance test, winding-to-winding and winding-to-ground.
  • Turn to Turn ratio test: to determine actual vs. calculated voltage
  • Power Factor Test: to assess the condition of electrical insulation in high voltage apparatus
  • Breaker and relay tests of contact resistance, conductivity, insulation resistance, current and /or voltage trip levels

Equipment Used

  • Microprocessor-based circuit breaker test sets for high-current injection
  • 5KV Insulation Resistance testers
  • Automated insulation power factor test set
  • Protective relay test set
  • Digital Low Resistance Ohmmeters
  • 10KV automated power factor test set
  • Turn to Turn ratio test set
Transformer Service Inc.


Our breaker and relay test process compare the performance of your equipment to the manufacturer’s maintenance specifications. In addition to testing, our technicians perform on-the-spot repairs such as:

  • Cleaning cubicles
  • Burnishing and adjusting contacts
  • Lubricating moving parts
  • Retrofitting trip units
  • Repairing faulty subassemblies

More extensive repairs are performed by returning the faulty item to TSI or on a subsequent site visit.

Test Report and Analysis

After the test program is completed, a test report is compiled and submitted to our customer. The test report presents the actual data taken at the customer’s site and the results of any calculated values. Out-of-specification conditions are highlighted and maintenance recommendations are presented.