TR 300

Transformer Turns Ratio Tester

The TR 300 is a true three-phase transformer turns-ratio instrument designed to test any type of transformers. It performs turns ratio tests per the IEEE C57.12.90 measurement standard. The TR 300 generates its own three-phase excitation test voltage which is applied to the three phases of the transformer’s primary windings. The three-phase secondary voltages are measured to calculate the turns ratio.

The TR 300’s measuring range is 0.8-50,000 : 1. In addition to measuring turns ratio, the TR 300 can also measure excitation current and phase angle difference between the primary and secondary voltages. The test results can be displayed on the unit’s built in color display.

The TR 300 offers selectable test voltages of 5, 50, and 100V. Optionally, a 250V test voltage is available for testing in electrically noisy environments. The higher test voltages increase the measurement accuracy, especially at high turns ratios.

In addition, the test frequency of the voltage is 55 Hz so power frequency interferences of the substation do not affect the turns ratio measurement. Higher test voltages, coupled with off frequency measurement, make the TR 300 an ideal instrument for high accuracy testing.

To prevent an accidental wrong test lead hookup, such as when the operator reverses H and X leads, the TR 300 outputs a low-level test voltage to verify the hookup condition before applying the full test voltage to the transformer. Higher test voltages allow the TR 300 to test CT’s and PT’s, as well as power transformers.

The TR 300 generates its own three phase test voltages so that the turns ratio, excitation current, and phase angle can be measured simultaneously. This feature allows the TR 300 to also test special transformers such as phase-shifting transformers where the phase angle difference between the primary and secondary is not the standard 30 degrees.

The TR 300 features a rugged 44-key “QWERTY”-style keypad and a back-lit color LCD screen (800 x 480 pixels) which is viewable in direct sunlight and low light. An optional built-in 3.5 inch thermal printer can be used to print and review the test results in the field without the need for a computer.

The TR 300 can be computer-controlled via the USB interface or the Bluetooth wireless interface.

The load tap changer position or the voltage regulator tap position can be raised or lowered by the TR 300. The raise or lower command can be issued manually via the instrument’s front panel or automatically controlled by the instrument for greater productivity.

An optional built-in 3.5 inch wide thermal printer is available for printing test results in the field.

An optional battery backup is also available for testing transformers in situations where an AC power supply is not available. The battery backup can provide power for up to three hours. The TR 300 uses sealed lead acid batteries (12V, 7AH) that allow the unit to be used while charging.

  • Outstanding Features
  • Technical Specifications
  • Downloads
  • Off power frequency test voltages for high accuracy in electrically noisy high voltage sub stations
  • Optional battery backup for up to 3 hours of testing
  • Wide Ratio range: 0.8 - 50,000: 1, covers all types of transformers
  • Capable of detecting all types of 3-phase transformers defined by ANSI, IEC, and Australian standards
  • 4 available voltages: 5Vac, 50Vac, 100Vac, and 250 Vac (optional)
  • Phase angle and excitation current measurement covers all types of transformers including phase shifting transformers
  • Bluetooth and USB PC interfaces
  • Optional built-in 3.5-inch wide thermal printer for quick field analysis of test results

Physical SpecificationsDimensions: 21"w x 8" H x 17" D (53 cm x 20.5 cm x 43 cm)
TR 300 Weight without Battery: 24 lbs. (11 Kg)
TR 300 Weight with Battery: 26 lbs. (12 Kg)
Operating Voltage90- 240 Vac, 50/60 Hz
Measuring MethodANSI/IEEE C57.12.90
Turns Ratio Accuracy4 Vac: 0.8 - 20,000: ±0.05% typical max 0.3% for the entire range
40 Vac: 0.8 - 50,000: ±0.05% typical max 0.2% for the entire range
100 Vac: 0.8 - 50,000: ±0.05% typical max 0.2% for the entire range
250 Vac: 0.8 - 50,000: ±0.05% typical max 0.2% for the entire range
Phase Angle Measurement0 - 360 degrees
Accuracy±0.2 degree (±1 digit)
Polarity ReadingIn-phase or out-of-phase indication
Current Reading Range0 - 1 Ampere; Accuracy: ±0.1 mA, ±2% of reading (±1 mA)
Display800 x 480 pixels back-lit color LCD; viewable in direct sunlight and low light
Computer InterfacesUSB 2.0, Bluetooth
Internal Data Storage128 records of 99 readings
Internal Test Plan StorageStores up to 128 transformer test plans; test plans can be transferred to PC
External Data StorageUSB flash drive interface (drive not included)
Tap Changer Contacts240 V AC, 2A
Battery Back-up (optional)12 V AC, 7 AH for 3 hours of operation
Printer (optional)3.5" wide thermal printer
Test ResultsAuto-detection of transformer configuration
PC SoftwareWindows®-based transformer analysis software is included
SafetyIEC/EN 61010-1, EN 61326-1, EN 61000-3, and EN 61000-4 certified.
UL 61010A-1, and CSA-C22.2 standards.
Humidity90% RH @ 40°C (104°F) non-condensing
TemperatureOperating: -10°C to +50°C (+15°F to +122°F)
Storage: -30°C to +70°C (-22°F to +158°F)
Altitude2,000 m (6,562 ft)
Included CablesOne 15' (4.57m) sing-phase cable set, one 15' (4.57m) 3-phase cable set, one 25' (7.62m) exctension cable set, one safety ground cable, one USB cable, cable bag
WarrantyTwo years on parts and labor
OptionsShipping case (can hold unit and cables), printer, battery back-up

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5010 E. Shea Blvd.
Suite 240
Scottsdale, AZ 85254
Phone: +1-602-732-1099

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