Category: Winding Resistance Testers

Winding Resistance Testers

Winding Resistance Testers measure highly inductive windings of the transformer, motors, and reactors to analyse the performance of the measured UUT.

  • 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


  • Three Phase Transformer Measuring Bridge | MLS 7100

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    Three-Phase Transformer Measuring Bridge - Overview

    The MLS 7100 was particularly designed to simplify the determination of transformer core and copper losses, which is an ideal choice when working on site. The measuring bridge features open-circuit as well as short-circuit measuring. Many transformers can be directly connected to the MLS 7100 without needing further transducers. Core losses are an important transformer quantity in electrical efficiency, operating expenses, and the overall transformer value.

    Steel losses are typically determined using open-circuit measurement, as a relatively small magnetising current is flowing. Using this technique, the copper losses are minimized due to the square correlation of power and current. Copper losses are determined using short circuit measurement, as the magnetising modulation of the steel core should be minimized. In addition, the short circuit voltage is determined this way, which is also an important quantity.

    Three Phase Transformer Measuring Bridge - Features

    • Open circuit measurements
    • Short circuit measurements
    • Free selectable voltage and current dividers
    • 1000 kV with transducer
    • 1000 kA with transducer
    • 550 V (chained) 6 A directly connectable
    • Measures and displays:
      • Voltages
      • Currents
      • Power
      • Short Circuit Values
      • Frequency
    • Centronics printer port
    • RS232C port for external control


  • Winding Resistance Transformer and Motor Meter MR8050

    Winding Resistance Transformer and Motor Meter | MR 8050

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    Winding Resistance Transformer and Motor Meter - Overview

    The MR8050 can measure highly inductive windings of transformers, motors, and reactors with a range of 100µΩ with 0.01µΩ resolution up to 6kΩ. The performance of the measured objects can be up to 800MVA or even more. The magnetic loading of a transformer is performed quickly using a high loading voltage (60V), this is important for time-critical measurements (cooling curves).  The unloading of the transformer's core is fast and safe, as the energy is dissipated in the MR8050. The temperature of the measured objects can be pre-set or measured using a PT100 temperature sensor and the resistance is calculated for 20°C using the temperature coefficient for copper or aluminum heat-loss measurements. The resistance at t=0 (disconnection of load) is shown as a result of the internal regression algorithm. Two windings (mostly HV and LV) can be measured simultaneously in the DUAL measuring method. The MR 8050 also features automatic tap-changer control for measuring different taps without interrupting the measuring current.

    Winding Resistance Transformer and Motor Meter - Features

    • 2 channels for DUAL measurements
    • Measuring time short due to very fast uploading
    • Discharge time 1/10 of uploading time
    • Heat - loss measurements with regression algorithm
    • LCD-Display with 240 x 128 pixels with backlight
    • USB standard and RS232C 9600 baud
    • PT100 connector for PT100 temperature probe
    • Tap changer connector for automatic tap control
    • Warning system connector for a separate warning light
    • Internal test storage for up to 1000 measurements
    • Inputs full protected against static and transient voltages
    • Wide current ranges from 50mA to 60A