Features and Benefits
- Fast, easy hand-held operation. No need to
kneel or bend down to operate the instrument.
- Powered by six standard “AA” alkaline
batteries; no charger needed. Provides up to 12 hours of field
operation.
- Measures turns ratio range of 20,000:1, with a
high accuracy (±0.1%, 0.8 to 2000) at a low excitation voltage.
- 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.
- Perfect for meter shops, the TTR25 can be used
for inspection purposes to determine the no-load accuracy of most CTs
and PTs. It also can be used to determine the need to test potentially
faulty CTs and PTs.
- Automatic self-calibration for each test.
- User selectable languages: English, Spanish,
German, French and Portuguese.
Description
The Megger TTR25 is an automatic
hand-held battery operated transformer turns ratio test set. It is used to
measure the turns ratio, excitation current and polarity of windings in
single- and three-phase distribution and power transformers (tested phase
by phase), potential & current transformers, and tapped transformers.
The unique design of the TTR25
allows the user to operate the test set while holding it in one hand. It
effectively eliminates the user from having to kneel or bend down to
operate the instrument and speeds up testing time. Realizing the extreme
environments in which the TTR25 must operate, special attention has been
paid to making it extra rugged, with a high impact, shock resistant case,
yet incredibly lightweight at a mere 870 g (1.9 lbs).
Its design makes this instrument
well suited for use in a variety of harsh environments. The TTR25 is
particularly
suited for testing in substations, transformer-manufacturing environments,
and meter shops. It features a high-contrast, backlit LCD
screen which can be seen in bright or ambient light. This unit measures a
high turns ratio of 20,000:1 accurately with the lowest excitation
voltage.
The excellent repeatability of
the TTR25 helps the users to determine the condition of transformers under
test. It is designed for simple, one button operation with the measured
results displayed directly on the easy to read LCD or printed to the
optional printer. The TTR25 needs no additional software and comes ready
to use complete out of the box.
Applications
The proper operation of a transformer
relies almost entirely on the electrical properties of its windings. To
ensure continued proper operation, transformers are tested to verify
that their electrical properties have not changed from design
specifications. A TTR is an extremely useful instrument for testing
transformer windings because it can help locate several types of problems
within single- and three-phase transformers.
It it used to determine the no-load accuracy of CTs
and PTs and also determine the need to further test faulty CTs and PTs.
The TTR25 applies voltage to the high-voltage winding of a transformer and
accurately measures the resulting voltage from the low voltage winding.
The ratio of voltages is directly proportional to turns ratio. In
addition, the unit measures excitation current and polarity.
Transformer Turns Ratio
A Transformer Turns Ratio Test Set such as the TTR25 can directly measure
the turns ratio of single-phase transformers as well as three-phase
transformers. Deviations in these measurements will quickly indicate
problems in transformer windings and in the magnetic core circuits.
Transformer ratio can change due to several
factors, including physical damage from faults, deteriorated insulation,
contamination and shipping damage. If a
transformer ratio deviates 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 Megger TTR25 is needed.
Transformer Polarity
Polarity of a distribution transformer becomes of interest in order to
determine its proper connection within a power network. The Megger TTR25
will identify normal (in phase) and reverse polarity of the single-phase
transformers. |
