UT625B 200A Digital Low Resistance Ohmmeter

UNI-T UT625B 200A Low Resistance Ohm Meter

Precision Micro-Ohm Measurement with High-Current Testing Capability

The UNI-T UT625B is a high-precision low resistance tester designed for industrial applications requiring accurate measurement of contact resistance, connections, and other critical low-impedance components. With its impressive 200A maximum test current, 0.1μΩ resolution, and four-wire Kelvin measurement method, this professional-grade instrument delivers laboratory-level precision in demanding field environments. Featuring a user-friendly 7-inch color display, built-in thermal printer, and comprehensive data storage capabilities, the UT625B is the ideal solution for power system maintenance, transformer testing, circuit breaker analysis, and high-current connection verification where accurate low resistance measurements are essential for system reliability and safety.

Key Features

• Powerful 200A Test Current: Superior capability for accurate low resistance testing compared to standard 100A instruments
• Exceptional 0.1μΩ Resolution: Ultra-precise measurement across a wide range from 0.1μΩ to 2000mΩ
• Four-Wire Kelvin Test Method: Eliminates lead and contact resistance for maximum measurement accuracy
• Adjustable Test Duration: Flexible testing times from 10-60 seconds with 1-second increments
• Pass/Fail Comparison: Automatic evaluation against preset values for quick quality assessment
• 7-inch Color LCD Display: Clear visualization of measurements with 5-level adjustable backlight
• Built-in Thermal Printer: Instant documentation of test results for field reporting
• Comprehensive Data Storage: 200 sets of measurements with auto/manual/cyclical save options
• PC Connectivity: USB connection for advanced analysis and report generation
• Overheat Protection: Safeguards against thermal damage during extended high-current testing

Industrial-Grade Precision for Critical Low Resistance Applications

The UNI-T UT625B delivers exceptional measurement accuracy with its high-current testing capabilities and state-of-the-art four-wire Kelvin method. With accuracy ratings of ±(0.4%rdg+0.04%FS) across most of its measurement range, it offers laboratory-grade precision in a field-ready instrument. The impressive 0.1μΩ resolution enables detection of minute resistance variations critical for identifying degrading connections and incipient faults in high-power systems.

The unique ability to provide test currents up to 200A—double the capacity of standard 100A instruments—ensures reliable measurement of extremely low resistances, making the UT625B particularly valuable for high-current applications such as switchgear maintenance, power distribution equipment, and industrial bus bar connections where standard instruments often lack sufficient testing power.

Comprehensive Measurement Capabilities

The UT625B combines essential low resistance measurements with specialized industrial functions to deliver complete diagnostic capabilities. Beyond standard resistance testing, it offers:

• Multiple selectable test currents (5A, 10A, 50A, 100A, 200A) with 5A/10A stepping
• Customizable test durations from 10-60 seconds with 1-second precision
• Automatic comparison with preset resistance values (0.000~9999.9mΩ range)
• Self-calibration using the included 375μΩ shunt resistor for measurement verification
• Extended measurement range from 0.1μΩ to 2000mΩ with optimized resolution bands
• Automated noise suppression for stable readings in electrically noisy environments
• 10V DC open circuit voltage for reliable measurement of higher-resistance connections

The specialized four-wire Kelvin test method separates current and voltage measurement circuits, eliminating the influence of lead resistance and contact points to provide true resistance values even at extremely low readings. This capability is essential for accurately evaluating the integrity of high-current connections where even minor resistance increases can cause significant power losses and heating.

Durable Design and User-Friendly Operation

The UNI-T UT625B features a robust construction specifically designed for industrial testing environments:

• Rugged enclosure with integrated cooling system for sustained high-current operation
• Large 7-inch color LCD with 5-level adjustable backlight for all lighting conditions
• Intuitive interface with straightforward test parameter selection
• Built-in thermal printer for immediate documentation of test results
• Extended operating temperature range from -20°C to +50°C
• Overheating protection system for safe operation during extended testing
• Comprehensive set of professional accessories including heavy-duty test leads

These durability features ensure the instrument performs reliably in demanding environments including outdoor installations, power substations, industrial manufacturing plants, and heavy equipment maintenance facilities where environmental conditions would compromise standard instruments.

Data Management and Analysis

The integrated data storage and connectivity capabilities transform the UT625B from a simple measurement tool into a complete resistance analysis system:

• Store up to 200 measurement sets with timestamp information
• Flexible save options including automatic, manual, and cyclical modes
• Built-in thermal printer for immediate test documentation
• USB connectivity for PC-based data transfer
• Compatible software for comprehensive analysis including:
• Real-time measurement data analysis
• Historical data review and trending
• Professional Excel report generation

This connectivity enables technicians to document system performance over time, identify gradual degradation in connections before failures occur, and maintain comprehensive maintenance records for quality assurance and regulatory compliance.

Professional Applications

Power Distribution Systems

Power engineers and maintenance technicians rely on the UT625B's high-current capacity and precision for:

• Bus bar connection verification and maintenance
• Circuit breaker contact resistance testing
• Transformer winding resistance measurement
• Ground system connection integrity testing
• Substation connection point verification

Industrial Manufacturing

Manufacturing and quality control specialists leverage the UT625B's precision for:

• Welded joint quality verification
• High-current electrical connection testing
• Motor and generator winding resistance analysis
• Production line connection validation
• Quality assurance of electrical components

Transportation and Infrastructure

Maintenance professionals in transportation sectors depend on the UT625B for:

• Railway track circuit connection verification
• Vehicle and equipment grounding system testing
• High-current motor and starter system analysis
• Critical safety system connection validation
• Signal system ground resistance verification

Renewable Energy Systems

Solar and wind system technicians utilize the UT625B for:

• Solar panel array connection testing
• Wind turbine slip ring resistance verification
• Battery bank connection analysis
• High-current inverter connection points
• Grounding system integrity testing

Technical Specifications

Package Contents

• UNI-T UT625B 200A Low Resistance Ohm Meter
• 4-wire Test Clips (red and black), 1 pair
• Ground Cable, 1 piece
• Standard Shunt (375μΩ), 1 piece
• USB Cable, 1 piece
• AC Power Adapter, 1 piece
• Thermal Printer Paper, 1 roll
• Carrying Cloth Bag, 1 piece
• Quick Start Guide, 1 piece

Product Comparison

Frequently Asked Questions

Why is the 200A test current important for low resistance measurements?

The UT625B's 200A test current capability provides superior accuracy when measuring extremely low resistance values compared to standard 100A instruments. When testing components with resistance in the micro-ohm range, higher test currents produce more measurable voltage drops across the resistance, resulting in more reliable readings with better signal-to-noise ratios. This increased current is particularly valuable when testing high-current connection points like bus bars, circuit breaker contacts, and heavy conductor joints where the ability to simulate actual operating currents provides more meaningful results about the connection's performance under load conditions.

What advantages does the four-wire Kelvin test method provide?

The UT625B's four-wire Kelvin test method separates the current-carrying circuit from the voltage-sensing circuit, eliminating the effects of test lead resistance and contact resistance from the measurement. In low resistance testing, where the measured value might be only a few micro-ohms, the resistance of the test leads themselves can be significantly higher than the resistance being measured. By using separate pairs of leads—one pair to supply the test current and another pair to measure the voltage drop—the Kelvin method ensures that only the actual resistance of the component under test is measured. This technique is essential for accurate results when working with extremely low resistance values, providing precision that would be impossible with standard two-wire measurement methods.

How does the built-in thermal printer enhance field testing capabilities?

The UT625B's integrated thermal printer provides immediate documentation of test results directly at the measurement location without requiring additional equipment. This capability is particularly valuable for field technicians who need to document compliance testing, verify repairs, or provide immediate proof of system condition. The printed records include measurement date, time, resistance values, and test current information, creating an audit trail that can be included in maintenance reports. This on-the-spot documentation eliminates the potential for transcription errors that can occur when manually recording results and provides stakeholders with immediate verification of critical connection integrity in power distribution systems, industrial equipment, and safety-critical installations.

What is the significance of the extended measurement range to 2000mΩ?

The UT625B's extended measurement range up to 2000mΩ (2Ω) provides greater versatility for industrial testing applications. While micro-ohm and low milli-ohm measurements are critical for high-current connections, the ability to measure up to 2000mΩ allows technicians to use the same instrument for testing a wider variety of components including motor windings, transformer connections, relay contacts, and longer cable runs. This extended range eliminates the need to switch between multiple instruments when performing comprehensive system tests, streamlining the maintenance process and ensuring consistent measurement methodology across different components. The UT625B's automatic range optimization also ensures that the appropriate test current is applied for each resistance range, providing optimal accuracy across the entire measurement spectrum.

What is the warranty period for the UNI-T UT625B?

UNI-T provides a 1-year warranty on the UT625B, 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 UT625B 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 Low Resistance Testing for Maintenance Specialists

The UNI-T UT625B 200A Low Resistance Ohm Meter delivers exceptional precision, powerful test current capability, and specialized features for demanding industrial testing environments. With its 0.1μΩ resolution, four-wire Kelvin measurement method, and comprehensive data management capabilities, it provides reliable performance for maintenance professionals who need accurate low resistance measurements for critical power distribution systems, high-current connections, and safety-critical installations.

Order Your UNI-T UT625B Today and Experience Professional-Grade Low Resistance Measurement Capabilities