Winding Resistance Meters | Detailed introduction of technical principles

The core principle of a transformer winding resistance tester is the DC voltage drop method. A constant DC current is injected into the winding, and the DC resistance is calculated based on Ohm's law (R=U/I) by precisely measuring the voltage drop across the winding.

Due to the extremely high inductance of the winding, the instrument employs a "constant current-sampling" operating mode: first, a constant DC current (typically several to hundreds of amperes) is output to charge the winding. Once the current stabilizes and the inductive effect is largely eliminated, the instrument simultaneously and rapidly acquires the current (I) and the voltage (U) across the winding. The DC resistance of the winding under the test current can then be precisely calculated.

This test is one of the most fundamental and important tests for transformers. By measuring the DC resistance of each phase winding and comparing the unbalance rate between the three phases, as well as the deviations from factory data and historical data, defects such as poor welding of internal winding wires, loose lead connections, tap changer contact faults, and inter-turn short circuits can be effectively diagnosed. Transformer Winding Resistance Tester (5mA-10A)

The DC resistance of a transformer is a mandatory test item in the manufacturing process, including semi-finished and finished product factory tests, installation tests, commissioning tests, and preventive tests by the power sector. It effectively detects manufacturing defects such as material selection, welding, loose connections, missing strands, and broken wires in the transformer coils, as well as potential hazards after operation.

This transformer DC resistance tester is an innovative product with a built-in high-capacity lithium battery. Its compact size makes it easy to carry. It is suitable not only for measuring inductive test objects such as transformers, instrument transformers, and reactors, but also for measuring resistive test objects such as copper busbars, wires, and switch contacts. The instrument offers fast testing speed and high accuracy.

Features: Adapts to lithium battery power or 220V AC power supply. A single charge allows for continuous testing of the DC resistance of hundreds of transformers. The testing process is simple and convenient.

Six output current levels, with a maximum output current of 10A and a maximum output voltage of 25V. Automatic current selection is available for quick and easy operation.

Wide measuring range and high accuracy: 500uΩ～50KΩ, 1mA, 10mA, 100mA, 1A, 5A, 10A.

Features resistance-temperature conversion function.

Equipped with multiple protection functions including back EMF protection, wire breakage protection, power failure protection, and overheat alarm.

5.6-inch extra-large industrial-grade high-brightness color LCD screen, clearly visible even in strong sunlight.

Equipped with an external printer for easy data printing.

Features both internal storage and USB flash drive storage.