The lightest micro-ohmmeter in the industry - RMO-H

The lightest micro-ohmmeter in the industry - RMO-H


  • Portable - only 0.95 kg / 2.1 lbs
  • Powerful - regulated current up to 300 A DC
  • Automatic test current ramp
  • High capacity battery operated
  • Measurement range 0.1 μΩ - 2000 mΩ
  • Typical accuracy ± (0,1 % rdg + 0,1 % FS)
  • BSG measurement (both sides grounded)


The RMO-H series contains two models;

  • RMO-H2 (test current up to 220 A DC),

  • RMO-H3 (test current up to 300 A DC), hereinafter referred to as "RMO-H".

The RMO-H is a portable, battery-operated micro-ohmmeter based on state-of-the-art technology, using the most advanced battery mode and switching technique available today. The high-capacity Li-Po battery allows the generation of a ripple-free DC current of up to 300 A. The test current is user-selectable and generated in an automatically regulated test ramp. During the test, the RMO-H increases the current before the measurement and decreases it afterwards. This significantly reduces magnetic transients.

The RMO-H instrument can store up to 1000 measurements internally. The results are stored on the micro SD card. All measurements are time and date stamped. The DV-Win software allows downloading the results and creating and exporting test reports in different formats. Communication between the RMO-H and a PC is via a Bluetooth connection. The unit is equipped with thermal and overcurrent protection.


The typical application is to measure the resistance of non-inductive test objects:

  • High, medium and low voltage circuit breakers

  • High and medium voltage disconnect switches

  • High current busbar joints

  • Cable splices

  • Welding joints

Connection of the RMO-H to the test object

The connection diagram of the RMO-H devices corresponds to the Kelvin measurement concept (four points). The measurement cables of the "Voltage Sense" plugs are connected as close as possible to Rt, and between the power supply cables. In this way, the resistance of the cables and clamps is almost completely excluded from the resistance measurement.

For the measurement of the contact resistance of a medium voltage switch with the RMO-H, it is advisable to use the cables with the same length. Cables with Kelvin probes (with trip button) are specially designed for this application.

When testing live tank HV switches with the RMO-H, a different cable length can be used. The short cable (red cable, 1.3 m) connects the RMO-H to the switch bushing near the test person and the device. The long cable (black cable, 3 or 5 m) is connected to a bushing further away from the breaker point.

BSG testing (both sides grounded)

The RMO-H device provides safe measurement of circuit breakers with both terminals connected to ground. The connection diagram is the same as for circuit breakers with one side grounded. Note: This type of measurement may be less accurate compared to a one-sided grounding measurement, due to a small amount of current that may flow through the ground connections.

Benefits and Features

The RMO-H is a portable instrument ideal for field and factory testing, with a very easy to use interface. The user only needs a few clicks to set up and start a preferred test. This is achieved with an intuitive keyboard and menu design. Unlike other types of portable micro-ohmmeters available on the market, the RMO-H device has a regulated test current, generated in a test ramp that is automatically regulated. This allows the following unique features:

  • User-selected test current.

  • A constant DC current (ripple-free) during the measurement.

The high capacity Li-Po battery (5600 mAh) allows multiple measurements without the need for recovery time between tests. The instrument has a very high typical accuracy ± (0.1% rdg + 0.1% FS), with the best resolution of 0.1 μΩ. The additional feature is the pass/fail criterion implemented through the Rmax function. When this function is activated, the RMO-H device displays information if the measured resistance is higher than the set Rmax resistance value.

DV-Win software

*included in the purchase price

The DV-Win software for the RMO-H device is a set of tool applications based on the Windows operating system. It enables two-way communication between the RMO-H device and a standard PC via Bluetooth connection. The main features of the software are:

  • Downloading test results to a PC

  • Analysis of test results

  • Save test results in different formats

  • Test Reports

Download the catalogue: The lightest micro-ohmmeter in the industry - RMO-H.

Download the catalogue of The lightest micro-ohmmeter in the industry - RMO-H.

If you want to acquire Microhmmeters with quality, you can also consult prices of Microhmmeters.

If you have any doubts or need advice from our engineers, don't hesitate to contact us and we will be pleased to help you. You can also call us at (+34) 982 20 99 20.