Hioki RM3548 Portable DC Resistance Meter

Hioki RM3548 – Portable DC Resistance Meter (3mΩ to 3MΩ)

High-Accuracy Portable Resistance Meter

Hioki DC resistance meters measure a broad range of resistance values at a high level of precision. The RM3548 is a high-precision, portable resistance meter capable of measuring resistance levels from microohms to megaohms, and is intended primarily for use in testing and maintenance of large equipment, for example, measuring the winding and weld resistances in large motors.

High-precision specs in a portable package

Continuity and resistance measurement in large transformers, motors, and power supply equipment

The RM3548 uses a high current of 1 A to measure lower resistance values more reliably at a resolution of 0.1 μΩ in applications including measuring resistance in large transformers and motors as well as wiring, busbars and connections in power supply equipment.

Verification of continuity of ground lines in automobiles and fuselage welds and caulking in aircraft

The RM3548 can be used to check ground connections* in automobiles and fuselage welds and caulking in air- craft using a measurement current of 300 mA (300 mΩ range).

Expansive range options

• Measure from 0.0 μΩ to 3.5000 MΩ
• 0.1μΩ max. resolution, 0.02% basic accuracy
• Max. measurable current of 1A

Portable resistance tester that’s ideal for low-resistance measurement and testing of large transformers and motors

This resistance tester features a portable design that’s easy to use when performing maintenance work in the field.

You can wear the instrument over your neck with the included strap, leaving both hands free to hold the clip-type leads while making measurements.

The instrument can be powered by eight AA alkaline batteries for about 10 hours of measurement. (Operating time varies with measurement conditions.)

Auto-hold and auto-memory functionality

The RM3548 features auto-hold and auto-memory functionality to automatically hold and record data simply by placing the probes in contact with the desired measurement location. This functionality allows measured values to be recorded automatically as soon as they stabilize without the need for the user to operate any switches.

LED Comparator Attachment

By installing the LED Comparator Attachment close to a probe, you can capture judgment results without moving your eyes away from the measurement location and probe.

Offset Voltage Compensation (OVC)

Thermal EMF occurs at the contact point of different metals. This voltage affects measurements, and if large enough, can cause measurement errors. The offset voltage compensation function minimizes the effect of thermal EMF to maintain measurement accuracy. Particularly when measuring low resistances where the detection voltage is small, and during low-power resistance measurements, OVC is essential to maintain accuracy.

Length conversion function

By setting a resistance value per meter, it is possible to convert resistance values into lengths. This capability is useful when managing cable inventory or estimating PCB pattern lengths.

No zero adjustment

Accuracy is defined without any need to perform zero-adjustment. Measurement can be performed as soon as the instrument is turned on.

Dramatically improved over-voltage resistance

Protection is provided against over-voltage input of up to 70 V, preventing damage caused by connecting the instrument to an electrical charge or by the effects of the counter-EMF from inductance.

Acquire measured values recorded in the instrument’s memory over a USB connection

By connecting the RM3548 to a computer with a USB cable, you can download measured values stored in the instrument’s memory. Since the RM3548 provides a mass storage class (read-only) USB interface, there is no need to install special driver software on the computer

Reduce the effects of thermoelectromotive force with the offset voltage correction

Thermoelectromotive force refers to the potential difference that occurs at junctions between different metals (see figure). Specifically, the phenomenon occurs where measurement probes and measurement targets come into contact, and at connections between measuring instruments and measurement leads.

The magnitude of this thermoelectromotive force varies with the temperature of the measurement environment, increasing as the temperature difference grows.

The RM3548 includes an offset voltage correction function that applies the measurement current in both the positive and negative directions and then uses the resulting detected voltages to eliminate the effects of thermoelectromotive force.

Correct resistance values, which vary with temperature, to a reference temperature with the temperature correction function

Temperature correction functions can convert readings to resistance values at a user-specified reference temperature and display the results, even for materials such as copper wire whose resistance varies with temperature. The RM3548’s temperature correction function converts the measured resistance value Rt at the current temperature t to the resistance value Rt0 at the reference temperature t0, as shown in the figure. The Temperature Sensor Z2002 (which comes with the RM3548) is used to perform temperature correction.