TRAN-203 transformer tester that measures everything in one

The TRAN-203 performs ratio tests following the measurement method of ANSI/IEEE C57.12.90. With a measurement range from 0.8 to 50,000 and an accuracy of 0.08%, the instrument covers both small distribution transformers and large power transformers in high-voltage substations.

The instrument operates in two modes:

• CT Mode – for current transformers, test voltages 1V and 4V
• PT Mode – for voltage transformers, test voltages 1, 4, 10, 40, 100, 250V AC

Alongside the ratio, the TRAN-203 also measures:

• Phase angle measurement (0–360°, accuracy ±0.2°)
• Polarity and ratio deviation (%)
• Core excitation current (up to 2A, accuracy ±0.1 mA)
• Magnetic balance between the three phases
• Vector group detection: automatic

With the 3-phase cable configuration you test all three phases without reconnecting the cables. This saves time and prevents connection errors.

By injecting up to 20 amperes DC, the TRAN-203 measures the resistance of primary and secondary windings at the same time. The measurement range runs from 0.1 µΩ to 100,000 Ω.

The resolution is 5 digits. On transformers with high inductance it takes a while before the reading is stable. For this you set a stability limit and a stability duration, after which the test stops automatically. When a fault occurs in the current loop, the software controls the current to limit damage and give the user extra protection.

The TRAN-203 has a built-in controller for on-load tap changers (OLTCs). You switch the taps from the menu, or automatically with Auto Tap, and measure at each tap position. A weakened contact in the tap changer causes heat development and, if left unchecked, can lead to a transformer failure.

A heat run (temperature rise test) is a type test that reproduces the heating under continuous nominal load. The TRAN-203 does not supply that load itself. It measures the winding resistance at up to 20A DC at an adjustable interval and uses this to determine the full load resistance R₀.

With an optional temperature sensor, the TRAN-203 corrects the measurement results for temperature automatically. You can also enter the temperature manually.

After a DC resistance measurement, residual magnetism may remain in the core. The TRAN-203 has a separate demagnetization test for this, which Hightest recommends after every winding test. This way the next measurement is not affected by residual magnetism. If energy remains stored in the transformer after a test, the TRAN-203 discharges it via its voltage channels.

The TRAN-203 is intended for technicians and test engineers working in or for:

• Grid operators and energy companies – periodic inspections of distribution and transmission transformers
• High-voltage substations – acceptance tests, measurements per tap position, fault diagnosis
• Installation companies and service providers – commissioning of new transformers (FAT and SAT)
• Test laboratories – verification after overhaul or rewinding work

The instrument is designed for both indoor and outdoor use. The housing is certified to IP67 (lid closed), so dust and temporary submersion in water will not damage the instrument. The operating temperature ranges from -10°C to +60°C.

The B models have an internal Li-ion battery for field use at locations without mains power. The BLUE models add wireless communication via Bluetooth for connection with the DMP software on a PC or laptop.

The TRAN-203 is available for rental at IONIO, including a valid calibration certificate, the complete original cable set (H and X test leads, extension cables, tap changer cable) and the DMP software. Our specialists can help with commissioning and the interpretation of measurement results.

Renting makes sense when you need the TRAN-203 once or only occasionally: for a commissioning, an annual inspection or a fault investigation. You get a calibrated, complete instrument without the cost of acquisition.

Browse all test and measurement systems available for rental or go directly to the TRAN-203 product page for the full specifications.

View our transformer test products.