Transformer Turns Ratio
Transformer Turns Ratio is the ratio of the number of turns in the high voltage winding to that in the low voltage
winding. A Transformer Turns Ratio Test Set such as the Three-phase Automatic TTR can directly measure the ratio of most types of transformers. Transformer ratio can change due to several factors, including physical damage from faults, deteriorated insulation, contamination and shipping damage. If a transformer ratio changes more than 0.5 percent from the rated voltage ratio, it may not operate reliably. To measure small ratio changes such as this, the accuracy of a Biddle TTR is needed.

Excitation Current
The exciting current is the current that maintains the magnetic flux excitation in the core of a transformer.
A Transformer Turns Ratio Test Set such as the Three-phase Automatic TTR is capable of measuring exciting current because they apply voltage to one of the transformers windings. An accurate measurement of exciting current can provide information about the condition of a transformer’s core. Unwanted circulating currents or unintentional grounds can affect the exciting current and indicate a problem.

Phase Angle Deviation
The phase angle deviation is the relationship between the voltage signal applied to the high voltage winding and the voltage signal extracted from the low voltage winding.

The phase deviation between the high and low side of a transformer is generally very small. If there is deterioration or damage in the transformer core, however, the phase deviation can change significantly. The Three-phase TTR can measure this phase relationship with the resolution necessary to detect a problem.
 

Features and Benefits

• Measures the widest turns ratio range in the industry (10,000:1) and also provides the highest accuracy (0.1%).

• Enables the operator to enter the ratio of the transformer and all of it’s taps. This allows the operator to know immediately when a tap is outside the acceptable limits. Also allows for a pass/fail limit so problem taps can be easily flagged.

• Comes equipped with “remote-control” switch for single person testing. This allows the operator to test transformers with “LTCs” very quickly.

• Records ratio errors for bushing CTs to an accuracy of ±0.1% nameplate. This reduces the need for additional test equipment and improves set-up time.

• Measures the phase deviation (in minutes) of the transformer primary versus secondary. This quickly indicates problems in the transformer such as partial shorted turns and core faults. This measurement is also useful in verifying phase errors in all types of PT's and CT's.

• Perfect for meter shops, the TTR can be used for inspection purposes by using it to determine the no-load accuracy of most CT's and PT's. Also, it can be used to determine the need to further test potentially faulty CT's and PT's.

• This instrument is also ideal for use by power
  transformer manufacturers. Its unique testing
  procedures and storage capability allows an operator to set up and test difficult three-phase transformers (with multiple tap changers and bushing CTs) in a quarter of the time than it used to take with the former Biddle TTR. This test also includes a pass/fail limit of individual ratios.
• A “Quick Test” Mode provides a fast determination of the turns ratio for single and three-phase transformers, thus saving time.
• Displays all values for each test including measured and calculated ratio, exciting current, ratio error, and phase angle deviation, thus providing comprehensive and conclusive data.
• Automatic self-calibration for each test.
• Rugged, lightweight design ideally suited for a harsh field and substation environment.
• Three user selectable standards: ANSI, IEC, and
  Australian. Also meets IEC 1010 as well as other safety standards such as CSA and UL.
• Six user selectable languages: French, German, Italian, Portuguese, Spanish and English.

Phone: 61 2 4353 4644 

Mobile: 0412 678 925