ZXR-1A ：Technical Performance and Power Industry Applications

Abstract

DC winding resistance measurement is a mandatory and critical test in the operation, maintenance, and fault diagnosis of power transformers, which enables early detection of winding defects, tap-changer contact abnormalities, and connection failures. Traditional DC single/double bridges, the conventional testing devices, have inherent limitations including extremely slow testing speed, poor on-site readability, weak anti-interference capability, and insufficient safety protection. This paper introduces the ZXR-1A Transformer Winding Resistance Tester, a high-precision upgraded alternative to traditional bridges, and systematically elaborates its core technical design, key performance indicators, and field application advantages in the power industry, providing a technical reference for power engineering technicians in equipment selection and on-site testing.

1. Introduction

Power transformers are the core equipment in power generation, transmission, and distribution systems, and their operational reliability directly determines the safety and stability of the entire power grid. DC winding resistance testing is an essential item in transformer handover acceptance, regular preventive maintenance, and post-fault diagnosis. This test can effectively identify hidden defects such as winding strand breakage, inter-turn short circuits, poor contact of on-load tap changers, and loose connection joints, which are difficult to detect through appearance inspection.

For decades, DC single and double bridges have been the mainstream devices for winding resistance measurement. However, they can no longer meet the efficiency and accuracy requirements of modern power system maintenance, with prominent shortcomings in practical engineering:

The low test current of bridges leads to extremely long core saturation and charging time for the large inductive load of transformer windings, resulting in very low test efficiency, especially for large-capacity power transformers.

Most traditional bridge products use LED displays, which have poor readability under strong outdoor sunlight, bringing great inconvenience to field tests.

Weak anti-interference performance makes measurement accuracy vulnerable to the complex electromagnetic environment in substations.

The lack of a reliable arc suppression circuit may cause equipment damage or safety risks from inductive overvoltage when the test is terminated.

To address the above limitations, the ZXR-1A Transformer Winding Resistance Tester is developed as a high-efficiency, high-precision replacement for traditional bridges. This paper analyzes its technical architecture, performance characteristics, and application value in the power industry, to guide on-site operation and maintenance personnel in standardized application.

2. Core Technical Design and Performance Advantages

2.1 High-Efficiency Fast Testing Technology

The most prominent advantage of the ZXR-1A tester is its ultra-fast testing speed, which is hundreds of times higher than that of traditional single/double bridges. This performance is derived from its advanced high-power switching power supply architecture, which provides a maximum output charging current of up to 1A.

For transformer windings, a typical large inductive load, the large test current can effectively compensate for current inertia, significantly accelerate the core saturation process, and greatly shorten the winding inductance charging time. In on-site maintenance, this feature drastically reduces the power outage duration of transformer overhaul, improves the work efficiency of operation and maintenance teams, and minimizes economic losses caused by power outages.

2.2 High-Precision Measurement Architecture

To ensure stable and accurate measurement of micro-ohm and milliohm level resistance in complex field environments, the ZXR-1A tester adopts two core technical schemes: the four-terminal (Kelvin) measurement method and a segmented high-stability constant current source system.

The four-terminal measurement method eliminates the influence of lead resistance and contact resistance on test results, which is the core premise for high-precision low-resistance measurement. Meanwhile, the segmented constant current source system outputs a matching test current according to the resistance range to ensure the stability of the charging current for inductive loads throughout the test:

1A for the range of 1μΩ ~ 2Ω

0.1A for the range of 2Ω ~ 20Ω

0.01A for the range of 20Ω ~ 200Ω

0.001A for the range of 200Ω ~ 2000Ω

This design avoids measurement errors caused by current fluctuations, and the instrument is equipped with high-precision imported core components, achieving a 0.5-grade measurement accuracy and a resolution of up to 1μΩ. It also has excellent anti-induction and anti-interference performance, maintaining stable and reliable test data in the strong electromagnetic interference environment of substations.

2.3 Wide Measurement Range and Environmental Adaptability

The ZXR-1A tester covers a full resistance measurement range from 1μΩ to 2kΩ, with 6 refined sub-ranges: 1mΩ~20mΩ, 20mΩ~200mΩ, 0.2Ω~2Ω, 2Ω~20Ω, 20Ω~200Ω, and 200Ω~2kΩ. This wide range enables the instrument to adapt to winding resistance tests of various types of transformers, from small-capacity distribution transformers to large-capacity power transformers in transmission systems, as well as other low-resistance inductive equipment tests.

The instrument can operate stably in an environment with a temperature of 0℃~40℃ and humidity ≤85%RH, fully meeting the environmental requirements of conventional field tests in the power industry.

2.4 Field-Friendly and Safety-Oriented Design

For the complex and variable field test scenarios in the power industry, the ZXR-1A tester has been optimized in terms of human-computer interaction, safety protection, and portability.

In terms of display, it is equipped with a 4-and-a-half-digit LCD for main measurement result display, and a 3-and-a-half-digit LCD for real-time ambient temperature or test current display. This dual-LCD design completely solves the problem of difficult reading under strong outdoor sunlight, which is a common pain point of traditional LED display products.

In terms of safety protection, the instrument has a built-in automatic arc suppression function. When the test is completed, it can effectively suppress the inductive overvoltage generated by the large inductance of the transformer winding, avoiding equipment damage and electric shock risks caused by arc discharge, and ensuring the safety of operators and equipment.

In terms of portability and power supply, the instrument integrates a built-in 12V rechargeable battery pack, supporting AC/DC dual power supply (AC 220V, DC 11V~14V). With a volume of 335×275×175mm and a weight of only 2.8kg, it has excellent portability, which is very suitable for on-site tests in substations and field tests in remote areas without a stable AC power supply. The power consumption of the instrument is ≤15W, ensuring a long battery life in DC power supply mode.

3. Key Technical Specifications

表格

4. Field Application Value in the Power Industry

In the daily operation and maintenance of power systems, the ZXR-1A tester has significant application value in multiple core scenarios:

Transformer Handover and Preventive Test: In the handover acceptance of new transformers and regular preventive maintenance of in-service transformers, the instrument can quickly and accurately complete winding resistance tests, identify early defects such as poor contact of tap changers and loose winding connections, and prevent major equipment failures caused by defect deterioration.

Transformer Fault Diagnosis: When a transformer operates abnormally, the instrument can provide high-precision winding resistance data to support fault location and cause analysis, providing a reliable basis for maintenance decision-making.

Complex Scenario Field Test: The AC/DC dual power supply design and portable structure make the instrument suitable for tests in various scenarios, including urban substations, remote mountain distribution networks, and temporary power supply sites. Its strong anti-interference ability ensures stable measurement in complex electromagnetic environments.

Maintenance Efficiency Improvement: Compared with traditional bridges, the ultra-fast test speed of the ZXR-1A tester can shorten the single test time from tens of minutes to a few seconds or minutes, which greatly reduces the power outage time of transformer maintenance, improves grid operation efficiency, and reduces the workload of operation and maintenance personnel.

5. Conclusion

The ZXR-1A Transformer Winding Resistance Tester is a new generation of high-precision test instrument developed for the actual needs of transformer winding resistance measurement in the power industry. It completely overcomes the inherent shortcomings of traditional DC single/double bridges, with outstanding advantages in test speed, measurement accuracy, anti-interference performance, portability, and safety protection.

For power engineering technicians, the ZXR-1A tester provides a reliable, efficient, and easy-to-use technical solution for transformer winding resistance testing, which can effectively improve the quality and efficiency of transformer maintenance, and provide strong technical support for the safe and stable operation of power systems.

GDZX is a manufacturer of power detection equipment, offering a diverse range of products with comprehensive models and providing professional technical support. Contact us at +86-27-6552607 or +86-17396104357.Website: http://en.gdzxdl.com/