2A DC Resistance Tester

The MOEORW-WBR02 is a digital DC resistance meter engineered for high-precision measurement requirements in both field and laboratory environments, and represents the mainstream upgrade path replacing traditional DC single-arm and double-arm bridges. As a transformer DC resistance tester, it incorporates advanced switching power supply technology and intelligent constant-current source control logic, enabling rapid and accurate measurements across application scenarios such as power transformers, reactors, and motor windings - all of which fall under the category of inductive load DC resistance meters. Compared with conventional bridges, this instrument improves testing efficiency by over a hundredfold, while eliminating subjective reading errors and delivering excellent measurement repeatability. The unit features a dual-display configuration with a 4½-digit LCD main screen for resistance readings and a 3½-digit LCD auxiliary screen for real-time test current or ambient temperature indication. Powered by a built-in 12V/2.2Ah rechargeable lithium-ion battery pack and supporting both AC and DC power supply modes, it serves equally well as a benchtop apparatus or as a portable DC resistance measuring instrument deployed to substations, transmission towers, and other off-grid field sites.

The instrument adopts a four-terminal Kelvin measurement architecture. An internal high-stability constant-current source delivers the set current to the test object via the I＋ and I－ terminals. After the current flows through the measured resistance Rx, the resulting microvolt-level voltage drop is picked up at the V＋ and V－ sensing terminals, conditioned by an instrumentation amplifier, and then converted by a high-resolution A/D converter, with the final resistance value displayed directly on the 4½-digit LCD. This four-terminal connection method completely eliminates additional errors caused by test lead resistance and contact resistance at the terminals (i.e., voltage drops at contact points A, B, C, and D), ensuring that the measured data truly reflects the effective resistance between points B and C. This is particularly critical for precision determination in low-resistance or high-inductive-load applications.

Accuracy Note: Class 0.5 means the maximum reference error does not exceed ±0.5% across the full-scale range. This specification is traceable to third-party metrology verification and meets the accuracy requirements for resistance test instruments as stipulated in power preventive test regulations.

Highlight 1: Ultra-Fast Measurement, Efficiency Revolution
The constant-current source features a fast settling time of less than 1 second. Combined with an optimized digital filtering algorithm, the average time from lead attachment to stable reading is only 3 to 5 seconds (subject to slight variation depending on inductance magnitude). Compared with the traditional manual balancing bridge that requires repeated galvanometer zero adjustments, this instrument improves testing efficiency by over a hundredfold, significantly reducing the total man-hours required for routine transformer testing. For batch inspection tasks, this speed advantage directly translates into substantial labor cost reduction and marked improvement in testing throughput.

Highlight 2: Wide Range Coverage, Multi-Purpose Versatility
This digital DC resistance meter eliminates the need for frequent external shunt replacements. A single unit covers a broad range from 1μΩ (e.g., copper busbar contact resistance) to 2kΩ (e.g., small-cross-section windings or cable DC resistance), completely eliminating the hassle of alternating between multiple instruments. Once the "Start/Stop" button is pressed to enter measurement mode, the instrument automatically locks the current range to prevent accidental range switching during testing, which could otherwise cause measurement interruption or data anomalies, ensuring the continuity and validity of every test result.

Highlight 3: Field-Friendly Design
Equipped with a wide-temperature LCD display, the instrument ensures clear readability of both main and auxiliary screens even under direct noonday sunlight, effectively overcoming the common issue of LED displays becoming illegible in bright outdoor conditions, so field testing is no longer constrained by lighting conditions. With AC/DC dual-mode power supply support, the built-in lithium battery can be directly utilized when no 220V outlet is available on site, providing continuous operation for over 6 hours (depending on the selected range current). This makes it a truly portable inductive load resistance meter, capable of operating in substations, transmission towers, tunnels, and other off-grid field sites.

Highlight 4: Active Safety Protection - Automatic Arc Suppression and Forced Discharge
After testing high-inductance specimens such as 110kV and above power transformers, the magnetic energy stored in the windings generates a high-voltage back-EMF at the moment of power disconnection. Improper handling can easily lead to personal injury or equipment damage. The instrument incorporates an active discharge circuit that automatically initiates a timed discharging sequence after the main power is switched off, with the panel discharge indicator illuminating throughout the process. The discharge lasts for at least 20 seconds, and lead removal is only permitted after the voltage has been dissipated to a safe threshold. This forced discharge sequence cannot be skipped or shortened, eliminating the safety risk of premature lead removal due to operator negligence through hardware logic, effectively ensuring operator safety and protecting the instrument's input-stage protection devices from overvoltage surges.

Highlight 5: Intelligent Charging Management and Long-Term Battery Maintenance
The unit is equipped with an intelligent charging management IC. When connected to AC 220V, the "Charging" indicator flashes during charging and remains steadily lit when fully charged, with triple protection against overcharge, reverse connection, and over-temperature. Users need not worry about overcharging damaging the battery or charging safety incidents. Even during extended periods of inactivity, the battery management system maintains low-power standby, keeping the self-discharge rate to an extremely low level. Users simply need to perform a supplementary charge maintenance cycle (approximately 14 hours) every two months to keep the battery pack in healthy condition. This design is particularly suitable for scenarios where batch-purchased units are distributed to multiple teams - even if a device remains unused for extended periods, it will not fail due to deep battery discharge, significantly reducing warehouse maintenance costs.

Highlight 6: High-Precision Metrological Assurance with Full Traceability
The instrument achieves Class 0.5 accuracy with a maximum resolution of 1μΩ, complying with the technical requirements for resistance measuring devices specified in the DL/T 845.3-2004 power industry standard. Every unit shipped undergoes full-range multi-point calibration, with calibration data archived for reference, and a factory metrology certificate is provided. For project acceptance scenarios where test reports must be submitted to clients, this traceability system ensures that every set of data measured by this instrument is fully traceable and credible, preventing acceptance disputes or rework caused by instrument accuracy issues.

As a contact resistance tester, this instrument is equally suitable for micro-ohm-level low-resistance measurements such as circuit breaker moving/stationary contacts and grounding flat steel lap joints, making it a standard configuration for substation maintenance crews and high-voltage test laboratories.

• Quality Control Traceability: Every unit shipped undergoes 72-hour high-temperature burn-in testing and full-range accuracy calibration, with calibration data archived for reference. Each instrument is accompanied by a factory metrology certificate (third-party provincial metrology institute certificates available as an option).
• Rapid Response Support: For volume procurement customers, we offer customized nameplates, dedicated instrument transport cases, and extended warranty services. Product operation manuals and training videos are included with each shipment to facilitate quick onboarding for end users.
• Continuous Upgradability: Our R&D team has been deeply engaged in the power testing sector for over a decade. Product software algorithms are eligible for free remote upgrades as industry standards evolve, ensuring your equipment does not become obsolete due to regulatory changes.