UT625A 100A Digital Low Resistance Ohmmeter

UNI-T UT625A 100A Low Resistance Ohmmeter

High-Precision Measurement with Professional-Grade Testing Power

The UNI-T UT625A is a high-precision 100A low resistance ohmmeter designed for professional electrical testing applications. Featuring exceptional 0.1μΩ resolution and advanced four-wire Kelvin measurement technology, it delivers laboratory-grade accuracy for critical resistance measurements in industrial environments. With its powerful 100A test current, customizable testing parameters, and comprehensive data management capabilities including built-in thermal printer and PC connectivity, the UT625A provides maintenance technicians, electrical engineers, and quality control professionals with the precision and reliability required for circuit breaker testing, bus connection verification, and other high-current connection point analysis in power distribution, manufacturing, and renewable energy applications.

Key Features

• 100A Maximum Test Current: Powerful testing capability for high-precision measurements
• 0.1μΩ Measurement Resolution: Exceptional precision for critical micro-resistance testing
• Adjustable Testing Current: Multiple current options (5A to 100A) with 5A/10A stepping capability
• Four-Wire Kelvin Test Method: Eliminates lead resistance for maximum measurement accuracy
• Built-in Thermal Printer: Instant documentation of measurement results
• 7-inch Color LCD Display: Clear visualization of measurement data and system status
• Comprehensive Measurement Range: 0.1μΩ to 1000mΩ range covers all professional testing scenarios
• Superior Measurement Accuracy: ±(0.4%rdg+0.04%FS) for reliable results
• Customizable Test Duration: Adjustable from 10 to 60 seconds for thorough diagnostics
• Pass/Fail Comparison Function: Automatic result evaluation against preset thresholds

Professional-Grade Precision for Critical Resistance Testing

The UNI-T UT625A delivers exceptional measurement accuracy with its impressive 0.1μΩ resolution and powerful 100A test current, providing the precision needed for critical resistance testing in industrial environments. The instrument's wide measurement range from 0.1μΩ to 1000mΩ covers virtually all low-resistance testing applications, while its superior base accuracy of ±(0.4%rdg+0.04%FS) ensures reliable results for informed decision-making in maintenance and quality control scenarios.

The specialized four-wire Kelvin test method separates current and voltage electrodes, eliminating the internal impedance of the instrument and the contact resistance of test leads. This advanced measurement technique is particularly effective for low-resistance measurements, minimizing errors and ensuring the highest level of measurement precision for critical electrical connections where even microscopic resistance variations can indicate developing problems.

Comprehensive Measurement Capabilities

The UT625A combines powerful testing capabilities with flexible parameter control to deliver complete diagnostic solutions for industrial applications. Beyond standard resistance measurement, it offers:

• Adjustable test current from 5A to 100A with 5A/10A stepping
• Customizable test duration from 10 to 60 seconds
• Resistance value comparison with automatic pass/fail evaluation
• Built-in 50-60Hz noise suppression for stable measurements
• Automatic measurement storage with 200 data point capacity
• Self-calibration capability using included standard resistor
• Overheating protection for reliable extended operation
• Multiple test result review and analysis options

The instrument's adjustable test current allows technicians to select the optimal testing power for each application, ensuring sufficient current for accurate measurement while protecting sensitive components. For critical circuit breakers and high-current connections, the full 100A test current provides definitive performance evaluation, while the stepping capability allows for progressive testing of connection quality under increasing current loads.

Intelligent Testing System

The UNI-T UT625A incorporates advanced testing intelligence to streamline the measurement process and enhance result reliability:

• Pass/fail evaluation against user-defined resistance thresholds
• Customizable test duration with second-by-second control
• Self-calibration function using included standard resistor
• Automatic data storage with circular save option
• 5-level adjustable backlight for all working environments
• Built-in thermal printer for immediate result documentation
• Comprehensive overheating and safety protection systems

These intelligent features transform the UT625A from a simple measurement device into a complete resistance analysis system, enabling technicians to conduct comprehensive testing protocols, document system performance, and identify developing issues before they result in system failure. The ability to preset acceptable resistance ranges and receive automatic pass/fail indications is particularly valuable for quality control applications and routine maintenance inspections.

Comprehensive Data Management

The integrated data management capabilities of the UT625A provide complete measurement documentation and analysis options:

• Store up to 200 sets of measurement data
• Auto/manual/cyclical storage options
• Built-in thermal printer for immediate documentation
• PC connectivity via USB for extended analysis
• Real-time data analysis on connected computer
• Historical data review and comparison
• Excel report generation for professional documentation

This robust data management system transforms measurement results into actionable intelligence, allowing maintenance teams to document system performance, track changes over time, and develop evidence-based maintenance schedules. The ability to generate professional reports with the included PC software streamlines documentation for maintenance records, regulatory compliance, and team collaboration.

Professional Applications

Power Distribution Systems

Electrical engineers and maintenance technicians rely on the UT625A's precision and power for:

• Circuit breaker contact resistance verification
• Bus bar connection quality assessment
• Switchgear contact resistance measurement
• Cable termination resistance testing
• Joint resistance verification in power networks

Industrial Manufacturing

Quality control professionals leverage the UT625A's accuracy for:

• Welding quality verification
• Metal-to-metal connection inspection
• Contact resistance measurement in assembled products
• Production line quality control testing
• Component specification verification

Renewable Energy Systems

Solar and energy storage technicians utilize the UT625A for:

• Solar panel connection resistance measurement
• Battery terminal and interconnection testing
• Inverter connection quality verification
• Ground system continuity assessment
• Conductor splice resistance measurement

Railway and Transportation

Transportation maintenance teams depend on the UT625A for:

• Rail bond resistance measurement
• Vehicle ground connection testing
• Power system connection verification
• Electrical junction resistance assessment
• Safety system continuity verification

Technical Specifications

General Specifications

• Data Communication: USB connection to PC software
• Self-Calibration: 750μΩ standard resistor included
• Input Power Supply: AC198V~242V (50/60Hz)
• Built-in Printer: Thermal printer for result documentation
• Backlight: 5 levels adjustable
• Over-Range Indication: "OL" for over-limit, "LO" for under-limit
• Working Environment: -20°C~+50°C; <85% R.H., no condensation
• Storage Environment: -30°C~+60°C; <85% R.H., no condensation
• Product Dimensions: 357mm×293mm×193mm
• Product Weight: 6.4kg

Package Contents

• UNI-T UT625A 100A Low Resistance Ohmmeter
• 4-wire Test Clips (red and black), 1 pair
• Ground Cable
• 750μΩ Standard Resistor (Shunt)
• USB Cable
• AC Power Adapter
• Thermal Printer Paper Roll
• Cloth Carrying Bag
• User Manual
• Certificate of Calibration

Product Comparison

Frequently Asked Questions

Why is the four-wire Kelvin test method superior for low resistance measurements?

The four-wire Kelvin test method used by the UT625A separates the current and voltage electrodes, eliminating the internal wiring impedance of the instrument and the contact resistance of test leads. This separation is critical when measuring extremely low resistances, where even small additional resistances from test leads would introduce significant measurement errors. By injecting current through one pair of leads and measuring voltage drop through a separate pair, the Kelvin method delivers dramatically improved accuracy, often 10-100 times more precise than two-wire methods, making it the industry standard for high-precision resistance measurements below 1Ω.

How does the adjustable test current benefit different testing applications?

The UT625A's adjustable test current (5A to 100A) provides significant flexibility across different testing scenarios. Higher test currents are essential for accurate measurement of extremely low resistances, allowing for better resolution and signal-to-noise ratio. However, some components may have current limitations or could be damaged by excessive test currents. The ability to select precise current levels allows technicians to follow manufacturer specifications for circuit breaker testing, adjust current based on connection type, and balance measurement accuracy with component safety. The 5A/10A stepping capability also enables progressive testing to identify resistance changes under increasing current, which can reveal connection issues not apparent at lower currents.

What advantages does the built-in thermal printer provide?

The UT625A's built-in thermal printer offers immediate documentation of test results directly in the field without requiring additional equipment or computer connections. This on-the-spot documentation capability is invaluable for regulatory compliance, providing instant proof of testing for inspection requirements in critical industries like power generation, transportation, and manufacturing. The printed records include complete test parameters (current, duration) alongside measurement results and timestamp information, creating a permanent record that can be included in maintenance files. This eliminates transcription errors and provides verified test documentation that can be referenced for future comparisons, making it particularly valuable for maintenance teams tracking connection performance over time.

Why is 0.1μΩ resolution important for industrial applications?

The UT625A's 0.1μΩ resolution represents measurement precision that is essential for several critical industrial applications. In high-current electrical systems, even microscopic increases in connection resistance can generate significant heat when hundreds or thousands of amperes flow through the connection. The ability to measure at this resolution allows maintenance teams to detect developing problems before they reach failure thresholds. For large circuit breakers where manufacturer specifications may require contact resistances below 50μΩ, this resolution provides the granularity needed to verify compliance. In applications like railway bond testing or data center power distribution, where connection resistance directly impacts system efficiency and safety, this level of resolution transforms the UT625A from a simple tester into a predictive maintenance tool that can identify declining connections long before conventional methods would detect a problem.

How does the data management system enhance maintenance operations?

The UT625A's comprehensive data management system transforms individual measurements into actionable maintenance intelligence. By storing up to 200 measurement sets with complete test parameters, the system enables technicians to establish baseline performance for critical connections and track changes over time. The USB connectivity and included PC software provide powerful analysis capabilities, allowing maintenance teams to visualize resistance trends, compare measurements across multiple test periods, and generate professional documentation for maintenance records. This capability is particularly valuable for implementing condition-based maintenance programs, where decisions are based on actual component performance rather than fixed schedules. The Excel report generation feature streamlines documentation for regulatory compliance, while the ability to archive and search historical data creates an invaluable resource for troubleshooting and performance optimization.

What is the warranty period for the UNI-T UT625A?

UNI-T provides a 1-year warranty on the UT625A, covering manufacturing defects and component failures under normal use conditions. This standard warranty ensures your investment in professional measurement equipment is protected, giving you confidence in your purchase decision.

Support and Warranty

UNI-T stands behind the UT625A with comprehensive technical support and a 1-year warranty. Our dedicated support team is available to assist with application questions, measurement techniques, and warranty service.

Professional-Grade Resistance Measurement for Critical Applications

The UNI-T UT625A Low Resistance Ohmmeter delivers exceptional precision, flexible testing capabilities, and comprehensive data management for demanding industrial applications. With its 0.1μΩ resolution, powerful 100A test current, and advanced four-wire Kelvin test method, it provides reliable performance for maintenance professionals who need high-precision resistance measurements for today's critical industrial systems.

Order Your UNI-T UT625A Today and Experience Professional-Grade Resistance Measurement Capabilities