Category: Transformer Turns Ratio Testers

Transformer Turns Ratio Testers

Transformer Turns Ratio Testers measure transformation ratio, phase error & magnetizing current of transformers for single/three-phase, power/distribution.

  • Winding Resistance and Turns Ratio Meter | MRC7300A

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    Winding Resistance & Turns Ratio Meter - Overview

    This instrument can precisely and safely determine winding resistances, transformation ratios, and phase angles of distribution transformers up to 100MVA and more. Further, it is possible to automatically move the tap charger of the H.V. winding to the next tap and perform cool-down measurements in temperature rise tests to calculate the resistance in the case of a load disconnection. The Winding Resistance & Turns Ratio Meter MRC7300A can be used by transformer manufacturers, electricity supply companies, and repair companies which carry out on-site measurements under unfavourable conditions. Resistance values ranging from 50 µΩ to 500 µΩ can easily be measured and logged with the internal measuring current of a maximum of 15 A up to a power of Approx. 100 MVA and more. To allow a comparison of the measured values to previous measurements, a conversion of the temperature of the test object is provided to compare measurements of a detached transformer carried out in winter and measurements carried out in other seasons. The measuring range is between 0.9:1 and 2500:1 in the case of the transformation ratio; the resolution of the angle measurement is 0.1 degrees. The logging of all measured values is performed by a separate printer, computer, or via the internal memory. The magnetic loading of the transformer is performed quickly to a relatively high rating voltage (50V). The unloading of the core is very safe, as the energy is dissipated in the MRC7300A by a ballast resistor and varistors except for a negligible rest.

    Winding Resistance and Turns Ratio Meter- Features

    • Automatic measurement without any manual interaction
    • Resistance measurement with high accuracy and up to 15 A current
    • Ratio measurement including phase angle and magnetizing current
    • Dual measuring method for faster measurements
    • Automatic vector group detection
    • Tap changer control measures all transformers tap automatically
    • Heat-up measurement including an algorithm for resistance at t=0
    • Temperature measurement and compensation to 20 °C for Cu or AI
    • USB port to get full external control over the instrument
    • Thermo printer


  • Battery Operated Transformer Ratio Meter PWR1-3B

    Battery Operated Transformer Ratio Meter | PWR1-3B

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    Battery Operated Transformer Ratio Meter - Overview

    The Battery-Operated Transformer Ratio Meter PWR1-3B is a battery-powered instrument that can also be driven by normal line voltage. It is designed to measure transformation ratio, phase error, and magnetizing current of power and distribution transformers for all three-phases simultaneously. Voltage and current transformers are single-phase, power transformers normally are three-phase. Due to the bad quality of industrial lines (phase jitter and shifting, voltage differences between the three phases) all measurements normally are done in single-phase, even on three-phase ratiometers. The design of the PWR1-3B contains an internal sinus power oscillator which delivers the necessary exciting voltage with very low distortion and stable voltage not found in industrial lines. This allows for very stable and precise single and three-phase measurements. The Battery-Operated Transformer Ratio Meter uses a large LCD display with a backlight to present the values of ratio and phase difference of “H.V. Winding” to “L.V. Winding”, and the excitation voltage and the magnetizing current of the high voltage winding. Additionally, the instrument performs self-calibration and has different warning messages before each measurement in case of reversed connections and other failures.

    Battery Operated Transformer Ratio Meter - Features

    • Ratio range from 8 to 2,500
    • Fully automated measurement
    • Measuring voltage 10 V / 100 V selectable
    • The display shows:
      • Ratio
      • Phase-angle
      • Excitation voltage
      • Magnetizing current
    • Easy to read large LC display for all three-phases with backlight
    • Built-in printer (optional)
    • A robust mobile case for field use


  • Three-Phase Transformer Turns Ratio Tester PWR3A

    Three-Phase Transformer Turns Ratio Tester | PWR3A

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    Three-Phase Transformer Turns Ratio Tester - Overview

    The great advantage of the Three-Phase Transformer Tester PWR3A is its simple set-up. You simply type in the vector group with the keys to set up, connect the transformer to the device, and release the measurement. All three phases are measured consecutively. All connecting and short-circuited procedures at the primary and secondary voltage sides are performed automatically before each measurement. It is also possible to measure just one phase. An adjustable set value allows an error or deviation of the measured transformation ratio to be displayed. Automatic control of the tap changer is provided. All phases and taps are measured consecutively, and the results are stored inside the instrument and transferred to a PC. The transformer-specific data can be easily programmed via a connected PC but it is also possible via the internal keyboard. The  PWR3A is connected to the H.V. and L.V. sides via four connections each. It also powers the test object at a selected voltage, supplied by an internal isolating transformer. An external excitation using different voltages and frequencies is also possible.

    Three-Phase Transformer Turns Ratio Tester - Features

    • Ratio range from 0.75 to 20,000 (higher ratios with CVT-Ext.)
    • Fully automated measurement
    • Features market unique Vector Group Detection
    • Measuring voltage from 8 V to 230 V
    • Measuring voltage up to 5 kV by CVT-Extension: PWR3A-CVT
    • Using 3-phase voltage for phase angles other than 0°/180°
    • Easy to handle tap changer automatic
    • Internal memory stores all dates (Reading with PWR3A-XFER)
    • LC display (256 x 128 pixel) with backlight
    • Easy input of vector group and measuring conditions
    • USB/RS232C port to get full instrument control
    • Centronics printer port or built in printer (optional)
    • Robust mobile case for field use
    • Factory Certificate