Product Introduction

       Measuring the DC resistance of transformer windings is a very important test item. In the "Power Equipment Test Regulations," it is ranked second among transformer test items. The regulations stipulate that the DC resistance of transformer windings must be measured during handover, major repairs, minor repairs, tap changer position changes, fault inspections, and pre-tests. The purposes are:

       ① Check the welding quality of internal windings and leads;
       ② Check whether the contacts of the tap changer are in good condition at each position;
       ③ Check for any breakage in the windings or leads;
       ④ Check the correctness of parallel branches and whether there are one or more broken wires in windings made of several parallel conductors;
       ⑤ Check for any short circuits between layers or turns.
        The NDZR-20A Transformer DC Resistance Tester is designed with microcomputer control and features a large backlit Chinese character LCD screen. It is easy to operate, with a clear and user-friendly interface. The measurement process and instrument status are clearly and fully prompted, eliminating the need for operators to memorize excessive procedures. It uses current source linear compensation technology, ensuring stable testing, high measurement accuracy, and fast speed, thereby improving measurement efficiency and reducing operator workload. The "four-terminal" measurement technique is employed to eliminate measurement errors caused by lead resistance and contact. It has overvoltage protection to guard against back EMF impacts. A panel printer can quickly print measurement results (optional). It is compact, lightweight, and portable. This instrument is suitable for measuring and analyzing inductive low-resistance values of various power transformers and mutual inductor windings.
       This product complies with the requirements of DLT 845.3-2004 "General Technical Conditions for Resistance Measurement Devices Part 3: DC Resistance Tester."

Product Features

☆ Fast testing speed: The instrument outputs a charging current of up to 20A, effectively compensating for the current inertia of large inductive equipment during measurement, accelerating core saturation, thus shortening charging time and improving testing speed. It is hundreds of times faster than traditional single or double bridge instruments.

☆ High accuracy: In addition to using an advanced four-terminal measurement method, the instrument also employs advanced constant current source technology, ensuring that the charging current for inductive loads remains relatively stable. It has stable anti-induction capability and strong anti-interference ability, thereby guaranteeing measurement accuracy. Moreover, it uses high-quality imported components, ensuring high measurement accuracy and good repeatability.

☆ Large backlit Chinese character LCD screen display, easy operation, clear and user-friendly interface, with clear and sufficient prompts for the measurement process and instrument status, eliminating the need for operators to memorize excessive procedures;
☆ Compact, lightweight, and portable;
☆ Panel printer for quick printing of measurement results (optional);

Technical Parameters

☆ Operating conditions:    Ambient temperature: 0℃～40℃, Relative humidity: ≤85％RH;
☆ Measurement range:    1mΩ～20Ω;
☆ Measurement accuracy:   1mΩ～20Ω ( ±0.2% RDG+2d );
☆ Resolution:   1μΩ;
☆ Constant current source:   1A, 5A, 10A, 20A;
☆ Power supply:   AC 50HZ  220V  (±10%);
☆ Power consumption:    ≤300W;
☆ Dimensions:   200mm x 400mm x 280mm;
☆ Weight:   8kg.