USB Milliohm, Earth Bond, Single & 3 Phase Motor Tester
Precision You Can Trust
NABL-Accredited Calibration | Available on Request
The Pico MT03A USB Milliohm, Earth Bond, Single & 3-Phase Motor Tester is a precision low-resistance testing solution for electric motors, transformers, earth bonds and electrical connections. It provides 10 µΩ resolution, autoranging resistance measurement up to 5 Ω, temperature compensation, Kelvin-clip testing, USB PC connectivity and three-phase winding measurements in under one minute. It also supports earth-bond testing with a minimum 200 mA test current for UN ECE R100 applications..
- Detail
- Special Features
- Specification
The Pico MT03A Milliohm and Motor Tester is designed for technicians, engineers, automotive specialists, industrial maintenance teams and research laboratories that need accurate low-resistance measurements.
It combines milliohm resistance testing, single-phase and three-phase motor winding testing, earth-bond measurement and temperature-compensated analysis in one USB-connected test system. Pico specifies a current resistance measurement range that autoranges up to 5 Ω, with a resolution of 10 µΩ and typical accuracy of ±(0.5% + 100 µΩ).
Precision Low-Resistance Measurement
The MT03A is designed for applications where conventional multimeters may not provide sufficient resolution for very low resistance values.
Key measurement specifications include:
- Resistance range: Autoranging up to 5 Ω
- Resistance resolution: 10 µΩ
- Typical resistance accuracy: ±(0.5% + 100 µΩ)
- Input protection: ±30 V
- Temperature compensation: Supported using the supplied temperature sensor
These capabilities make the MT03A suitable for measuring small resistance changes in windings, cables, earth bonds, busbars and electrical connections.
Three-Phase Motor Winding Resistance Testing
The MT03A can measure the resistance of all windings on a three-phase motor in under one minute.
It uses three Kelvin-connected measurement paths, allowing the resistance of the motor phases to be checked efficiently without repeatedly moving a conventional pair of test leads.
This is useful for identifying potential problems such as:
- Winding imbalance
- Loose electrical connections
- High-resistance joints
- Damaged windings
- Poor terminal connections
- Changes in motor winding resistance
- Electrical faults developing between phases
The software can display and compare winding resistance values to help engineers evaluate phase balance.
Single-Phase Motor Testing
The MT03A is not limited to three-phase systems.
It can also be used for low-resistance measurements on compatible single-phase motors and electrical components where detailed winding or connection resistance needs to be evaluated.
Typical uses include:
- Motor repair
- Preventive maintenance
- Manufacturing quality control
- Electrical troubleshooting
- Component verification
- Workshop testing
Temperature-Compensated Resistance Measurement
Electrical resistance changes with temperature, particularly in copper windings.
The MT03A includes a dedicated temperature sensor input and can automatically compensate measured resistance values according to temperature. This helps engineers compare the measured winding resistance against manufacturer specifications referenced to a standard temperature.
The current sensor specification provides:
- Temperature measurement range: −40 °C to +125 °C
- Temperature resolution: 0.2 °C
- Typical temperature accuracy: ±0.5 °C
Pico identifies the supported temperature sensor as TA527.
Temperature compensation can help prevent a healthy motor from appearing outside specification simply because the winding temperature differs from the manufacturer's reference condition.
Kelvin 4-Wire Resistance Measurement
The MT03A uses Kelvin measurement techniques to reduce the influence of test-lead and contact resistance.
Kelvin clips separate the current-injection and voltage-sensing paths, allowing the tester to measure the voltage drop close to the component under test rather than including the resistance of the test leads in the result.
This technique is especially useful for:
- Milliohm measurements
- Motor windings
- Busbars
- Earth straps
- Cable connections
- Welded joints
- High-current connections
Pico includes Kelvin clips with the MT03A kit.
Earth-Bond Testing
The MT03A also supports earth-bond resistance testing.
Pico states that the tester supports earth-bond testing in accordance with UN ECE R100 requirements and provides a minimum test current of 200 mA for relevant low-resistance measurements.
Typical earth-bond applications include:
- Electric vehicles
- High-voltage vehicle systems
- Chassis bonding
- Safety earth connections
- Ground straps
- ECU earth connections
- Battery and starter cables
- Welded conductive joints
- Electrical enclosures
For UN ECE R100 applications, Pico highlights measurement of resistance between exposed conductive parts and the electrical chassis.
Electric Vehicle Testing
The MT03A is particularly useful in electric and hybrid vehicle diagnostic environments.
Applications can include:
- Traction motor winding resistance
- Electric motor phase comparison
- Earth-bond testing
- HV component grounding
- Battery-system connections
- Busbar connections
- High-voltage cable connections
- Chassis bonding
- Electrical safety verification
Pico developed the MT03A for use across automotive, industrial and other electrical maintenance applications.
Transformer and Generator Testing
Pico also identifies the MT03A for applications including:
- Transmission transformers
- Distribution transformers
- Servo motors
- Generators
Low-resistance measurement can be useful for checking windings, connections and conductive paths in these systems.
USB PC Connectivity
The MT03A connects directly to a Windows computer through USB.
The USB connection provides:
- Data communication
- Power to the tester
- Software control
- Measurement display
- Data analysis
- Reporting
No separate external power supply is required during normal USB operation.
Dedicated MT03A Software
Pico provides dedicated Windows software for controlling the tester and reviewing measurement results.
The software supports:
- Resistance measurement
- Three-phase motor tests
- Temperature-compensated resistance
- Phase comparison
- Test-result display
- Measurement analysis
- Reporting
The current PC requirement is:
- Windows 10 or Windows 11
- 64-bit application
Typical Applications
The Pico MT03A is suitable for:
- Single-phase motor testing
- Three-phase motor testing
- Motor winding resistance testing
- Milliohm resistance measurements
- Earth-bond testing
- Electric vehicle diagnostics
- Hybrid vehicle testing
- Transformer testing
- Generator testing
- Servo motor testing
- Busbar resistance testing
- Ground strap testing
- Electrical cable testing
- Weld contact verification
- Industrial maintenance
- Rail applications
- HVAC systems
- Elevators and escalators
- Water-treatment equipment
- Mining and drilling
- Wind turbines and renewable energy
- Scientific research
- Manufacturing quality control
Autoranging Resistance Measurement up to 5 Ω
Pico's current product page specifies:
- Resistance measurement range: Autoranging up to 5 Ω
The autoranging system simplifies low-resistance testing by automatically selecting an appropriate measurement range.
10 µΩ Resistance Resolution
The MT03A provides a published resolution of:
- 10 µΩ
This makes it suitable for measuring very small resistance values in electrical connections, windings and conductive joints.
Typical ±(0.5% + 100 µΩ) Accuracy
Pico specifies typical resistance accuracy as:
- ±(0.5% of reading + 100 µΩ)
This should be used instead of generic wording such as "high precision" when listing formal technical specifications.
Three-Phase Testing in Under One Minute
The MT03A can test all windings of a three-phase motor in under one minute, helping reduce test time during diagnostics, repair and production verification.
Automatic Temperature Compensation
Measured resistance can be automatically adjusted according to the temperature measured by the included temperature sensor.
This is especially useful for motor and copper winding measurements, where resistance can change significantly as temperature changes.
Kelvin Measurement Technique
The included Kelvin clips use separate force and sense connections to minimize test-lead resistance errors.
The tester has dedicated:
- U-force and U-sense connections
- V-force and V-sense connections
- W-force and W-sense connections
UN ECE R100 Earth-Bond Testing
The MT03A provides a minimum 200 mA test current for applicable earth-bond measurements and is designed to support UN ECE R100 testing workflows.
±30 V Input Protection
Pico specifies:
- Input protection: ±30 V
This is a protection specification and should not be confused with the tester's normal low-resistance measurement range.
Dedicated Temperature Sensor Input
A rear-panel temperature sensor connection is provided for:
- TA527 temperature sensor
This enables automatic temperature compensation during resistance testing.
USB Powered
The MT03A is powered directly through its USB connection and does not require a separate external power supply during normal PC operation.
Long USB Test Connection
Pico's current product page lists supplied USB connectivity including:
- 4.5 m USB-A to USB connection
- 4.5 m USB-C connection
This provides flexibility when the PC must be positioned away from the component or vehicle being tested.
Portable Tester Design
The MT03A has published dimensions of:
- 190 × 141 × 42 mm
and weighs:
- Less than 0.5 kg
Pico also describes the tester as fitted with a rubber protective boot and hanging arrangement for workshop and field use.
Included Kelvin Clips
Kelvin clips are supplied to help reduce contact-resistance effects during low-resistance measurements.
Suitable for Multiple Industries
Pico identifies applications across:
- Electric vehicles
- Automotive
- Rail
- Industrial manufacturing
- Elevators and escalators
- HVAC
- Water treatment
- Mining and drilling
- Renewable energy
- Scientific research
Core Technical Specifications
| Specification | Details |
|---|---|
| Manufacturer | Pico Technology |
| Model | MT03A |
| Order Code | PQ326 |
| Product Type | Milliohm, Earth Bond and Motor Tester |
| Motor Testing | Single-phase and three-phase |
| Resistance Measurement Range | Autoranging up to 5 Ω |
| Resistance Resolution | 10 µΩ |
| Resistance Accuracy, Typical | ±(0.5% + 100 µΩ) |
| Temperature Resolution | 0.2 °C |
| Temperature Accuracy, Typical | ±0.5 °C |
| Temperature Measurement Range | −40 °C to +125 °C with supported TA527 sensor |
| Input Protection | ±30 V |
| Earth-Bond Test Current | Minimum 200 mA for applicable UN ECE R100 testing |
| PC Interface | USB |
| PC Operating System | Windows 10 or 11, 64-bit |
| Power | USB powered |
| Dimensions | 190 × 141 × 42 mm |
| Weight | Less than 0.5 kg |
Measurement Connections
| Connection | Function |
| U-Force | Current-force connection for U measurement |
| U-Sense | Voltage-sense connection for U measurement |
| V-Force | Current-force connection for V measurement |
| V-Sense | Voltage-sense connection for V measurement |
| W-Force | Current-force connection for W measurement |
| W-Sense | Voltage-sense connection for W measurement |
| Temperature Input | TA527 temperature sensor |
| PC Connection | USB 2.0 / USB 3.0-compatible interface |
The separate force and sense connections support Kelvin-style 4-wire low-resistance measurement.
Temperature Specifications
| Specification | Details |
| Supported Sensor | TA527 |
| Measurement Range | −40 °C to +125 °C |
| Resolution | 0.2 °C |
| Typical Accuracy | ±0.5 °C |
| Primary Purpose | Automatic temperature compensation of resistance measurements |
Environmental Specifications
| Specification | Details |
| Operating Temperature | 0 °C to 40 °C |
| Temperature for Quoted Accuracy | 15 °C to 30 °C |
| Storage Temperature | −20 °C to +60 °C |
| Operating Humidity | 5% to 80% RH, non-condensing |
| Storage Humidity | 5% to 95% RH, non-condensing |
| Maximum Operating Altitude | 2000 m |
| Maximum Storage Altitude | 15,000 m |
| Pollution Degree | 2 |
USB and PC Specifications
| Specification | Details |
| Connection | USB |
| USB Compatibility | USB 2.0 / USB 3.0 compatible |
| USB Cable Length | 4.5 m |
| Windows Support | Windows 10 and Windows 11 |
| Application Architecture | 64-bit |
| External Power Supply Required | No |