Product Introduction
This fast DC resistance tester (hereinafter referred to as DC resistance tester) is the product of the latest generation for measuring the DC resistance of transformer and is optimally designed for measuring the DC resistance of the three-phase winding of the large-capacity transformer. It can measure the DC resistance of the three-phase winding at the same time. In case of the on-load voltage regulating transformer, it is not required to discharge but to directly adjust the tapping switch. The measurement time is one third of the traditional single-phase measurement, greatly shortening the working time and labor intensity. As the DC resistor tester is provided with large-screen LCD and the graphical interfaces in Chinese, the operation is visual, clear and easy. Besides, it is provided with panel type printer and large-capacity non-volatile memory, so the measurement results can be stored and printed out easily. With good stability in data testing, speediness and perfect repeatability, it is the best choice for the on-site measurement of DC resistance of transformer.
Product functions
Three-circuit synchronous testing
Supports simultaneous current injection and synchronous measurement on all three-phase windings, completing three-phase DC resistance testing with a single connection.
Effectively shortens test time, improving efficiency by 2 to 3 times compared with traditional single-circuit testing.
Particularly suitable for power transformers with various connection configurations such as YN, Y, and Δ.
High-precision measurement
Adopts highly stable constant-current source and high-precision A/D sampling technology.
Measurement results are stable, reliable, and feature high resolution, meeting the requirements for factory, acceptance, and preventive testing of power equipment.
Automatically eliminates the influence of lead resistance and contact resistance.
Wide-range measurement
Output current is adjustable in multiple levels, automatically matching the test current according to transformer capacity.
Supports resistance measurement from micro-ohm to kilo-ohm levels, suitable for transformers and inductive equipment of various capacities.
Parâmetros técnicos
| Testing current | Single phase：1A 5A 10A 20A | ||
| Three phase：1A 5A 10A | |||
| Measurement scope | Single phase | ||
| 1A 10mΩ ～ 20Ω | |||
| 5A 1mΩ ～ 4Ω | |||
| 10A 1mΩ ～ 2Ω | |||
| 20A 1mΩ ～ 1Ω | |||
| Three phase | |||
| 1A 10mΩ ～ 6Ω （each phase） | |||
| 5A 1mΩ ～ 1Ω （each phase） | |||
| 10A 1mΩ ～ 0.6Ω （each phase） | |||
| Precisão de medição | ± (0.2%Full span ± 2 words ) | ||
| Maximum resolution | 0,1mΩ | ||
| Data storage capacity | 150 groups | ||
| Fonte de energia | AC 220V±22V，50Hz±2Hz | ||
| Ambiente de trabalho | Ambient temperature: 0°～40° Relative humidity :≤80% | ||
Product Features:
1. Simultaneously test the DC resistance of the three-phase winding of the transformer.
2. For on load tap changers, there is no need for discharge, and the tap changer can be directly adjusted. The measurement time is one-third of traditional single-phase measurement, which can greatly shorten the working time and labor intensity.
3. The direct resistance meter adopts a large screen LCD display with a fully Chinese graphical interface, which is clear and intuitive, and the operation is very simple.
4. And equipped with a panel printer and large capacity non-volatile memory, it can conveniently store and print measurement results.
5. The test data is stable, fast, and has good repeatability, making it the best choice for on-site measurement of transformer DC resistance.
Application Scenarios：
On-load tap-changer performance testing — Perform DC resistance measurement on each tap position of the transformer, analyze resistance variations across different tap positions, and determine whether the on-load tap-changer contacts have wear, erosion, or contact abnormalities, improving the operational reliability of the voltage regulation system.
Large transformer overhaul and fault diagnosis — After equipment major overhaul, winding replacement, or fault handling, re-test the winding DC resistance to verify repair quality, inspect winding connection integrity and conductive performance, and ensure the equipment is restored to normal operating condition.
Reactor and inductive equipment winding testing — Suitable for winding resistance measurement of inductive equipment such as shunt reactors, series reactors, and filter reactors. It can effectively determine winding continuity and internal connection quality, providing a reliable basis for equipment commissioning and maintenance.
Power equipment manufacturing and testing institution inspection — Widely used in transformer, reactor, and transformer manufacturing plants, testing centers, and quality supervision organizations for routine product testing, type testing, and quality spot checks, enabling high-efficiency and high-precision batch testing.
FAQ about Three-circuit Transformer DC Resistance Tester：
What are the advantages of three-circuit testing compared with single-circuit testing?
Three-circuit testing enables simultaneous current injection and synchronous measurement on all three-phase windings, eliminating the need for phase-by-phase switching and significantly reducing the number of connections and waiting time. At the same time, since test conditions are consistent across all three phases, the test data offers better comparability, effectively improving on-site work efficiency. This is particularly suitable for large-capacity power transformers.
What types of transformers is the three-circuit transformer DC resistance tester suitable for?
This equipment is suitable for various types of transformers, including oil-immersed transformers, dry-type transformers, distribution transformers, power transformers, step-up transformers, and step-down transformers. It can also be used for reactors, arc-suppression coils, and other inductive equipment requiring winding DC resistance measurement, meeting testing needs at different stages including manufacturing, installation, commissioning, and operation and maintenance.
Can the three-circuit transformer DC resistance tester be used for equipment condition assessment?
Yes. By comparing current measurement results with factory data or historical test records, the trend of winding resistance changes can be analyzed. Issues such as poor lead connections, winding deformation, tap changer contact abnormalities, and conductor aging can be promptly identified, providing a reliable basis for condition-based maintenance and equipment life assessment.
Matters needing attention:
1. When measuring an unloaded voltage regulating transformer, the discharge must be exited before switching the tap changer. The tap changer can only be switched after the discharge indication is complete
2. It is not allowed to dismantle the wiring during the measurement process.
3. If the charging progress bar and current display value remain stagnant for a long time, the measured winding resistance may exceed the current measurement range, and the current may not reach the preset value. At this point, you can press the 'Exit' button to return, select the current again, and try again.
4. When replacing the fuse and accessories, please use the same model as this instrument
