For reliable analysis of turns ratio accuracy, ATEC offers a variety of TTR Testers for rent at affordable rates from leading manufacturers including Megger and Omicron.
What Is A Transformer Turns Ratio (TTR) Test?
A transformer turns ratio (TTR) tester can verify the operating principle of a power transformer and identify any shorted turns or open-circuited conditions.
A transformer functions with a primary winding, or coil, sending an alternating current (AC) to a secondary winding. The process creates a mutual induction with voltage and current varying based on the number of turns on each winding. The ratio of turns on a primary winding compared to the turns on a secondary winding is the transformer turns ratio.
The TTR tester applies a low voltage to the primary winding, then records the voltage that comes from the secondary winding. That voltage from the secondary winding can determine if the transformer is working correctly or any possible issues with the equipment and its turns ratio.
The TTR test offers a safe and simple way to ensure that expensive transformers work correctly. A transformer should maintain a turn ratio within 0.5% of the nameplate specifications. TTR test results outside that range can reveal problems with the transformer that could get worse or more expensive down the line.
TTR test results can reveal many common transformer faults, including the following issues:
- Shorted Turns
- Phase-to-Phase Short
- Open or Burned Windings
- Turn-to-Turn Faults
- Magnetic Core Saturation
- Insulation Breakdown
How To Choose The Right TTR Tester Rental
From the number of phases to voltages, many different variables come into play when choosing a DC transformer. The same applies to choosing a TTR tester for the transformer. It's important to rent a TTR tester to fit all those specifications and your measurement needs.
Single-Phase Or Three-Phase TTR Testing
Rather than one set of primary and secondary windings used for a single-phase transformer, a three-phase transformer has three sets of windings. Still controlling the increase and decrease of voltage, a three-phase transformer is often used for larger motors and industrial applications.
Both TTR testers can work with single-phase and three-phase transformers, but a three-phase TTR tester offers extra functionality. Often able to handle a higher turns ratio, these TTR test kits also work with phase-shifting, arc-furnace, and other special transformers.
Turns Ratio Range And Accuracy
As the turns ratio gets higher, a TTR testing kit can struggle to maintain that precise accuracy. It's important that you not only rent a TTR tester that can analyze a very high turns ratio but do so accurately.
A model may be perfect for testing a turns ratio of 4000:1, keeping measurements within ±0.20%, but cannot handle a ratio that's over 10,000. Confirm that the TTR tester rental has a turns ratio range that surpasses your turns ratio, but maintains accuracy when testing the transformer.
Step-Up Or Step-Down Transformer
When the secondary winding has more turns than the primary winding, it is considered a step-up transformer. A step-up transformer increases the voltage from the primary coil to the secondary, while decreasing current. A step-down transformer has the reverse ratio, with more turns on the primary and a decrease in voltage and increased current.
While many TTR testers work with step-up and step-down transformers, not every model has both capabilities. The kit's turns ratio range may also change depending on which kind of transformer it is testing.