Transformer Loss Measuring System


The measurement of the losses in power transformers is an indispensable quality-verification process. Due to the fact that normally the transformer user puts a penalty on the losses that occur in the load and no-load modes, the greatest possible accuracy in measuring the power losses is of primary economic importance. The TLM system was specially developed for highly accurate measurements of power losses in transformers.

Using “State of the Art” proven current comparator technology, the TLM Series of transformer loss measurement systems is designed to meet the needs of today’s transformer manufacturer by providing the most accurate power loss measurement system in the world. Designed for power frequency testing and calibration, the TLM system can be used for testing small, medium and large power transformers and motors upto 400 Hz. The system is also ideal for R&D facilities. The TLM system can also be used to measure losses in single and three phase reactors.

The TLM offers an exceptional operating convenience. The measuring procedures are software supported. Time can be saved because the precision high voltage transformer requires no manual range selection. The risk of using wrong voltage or current range is thus eliminated.


  • Load loss measurement to reveal indications about stray losses and winding resistance.
  • No-load loss measurement to determine transformer excitation.
  • Heat run to verify temperature rises of oil and windings.
  • Induced voltage test to check the voltage withstand capability of the insulations.
  • Zero sequence measurement to identify phase sequence impedance.
  • Wattmeter function to perform quick and easy measurements without any calculations.


PC Based Controller

PC/Laptop controls the full system and runs understandable Windows user interface software.

TLM software has been especially designed for intuitive, fast, easy and safe user interrogations. Status information and test results are visualized by graphical symbols, values, pop-up windows and detailed graphs.

Technical Specification:

Voltage Measurement

Range Accuracy
100 V, 200 V, 500 V, 0.20 %
1 kV, 2 kV, 5 kV, 10 kV, 20 kV, 50 kV, 100 kV, 200 kV 0.15 %

Current Measurement

Range Accuracy
1 A, 2 A, 5 A, 10 A, 20 A, 50 A, 100 A, 200 A, 0.15 %
500 A, 1000 A, 2000 A, 4000 A 0.15 %

Power Measurement

Power Factor Range Accuracy
cos ϕ = 1.000 ≥ 100V, ≥ 5 A 0.07%
cos ϕ = 0.100 ≥ 100V, ≥ 5 A 0.10%
cos ϕ = 0.050 ≥ 100V, ≥ 5 A 0.15%
cos ϕ = 0.020 ≥ 100V, ≥ 5 A 0.50%
cos ϕ = 0.010 ≥ 100V, ≥ 5 A 0.70%
cos ϕ = 0.008 ≥ 100V, ≥ 5 A 0.80%