Micro-Ohmmeters
Contact resistance measurement is one of the most important and common tests during switchgear manufacturing, commissioning and maintenance stages. Besides switchgear testing, the RMO digital micro-ohmmeters are designed for simple, safe and efficient testing of:
disconnecting switches,
high-current bus bar joints,
cable splices,
welding joints,
and different high-current links in factory and high-induction field environments.
All DV Power RMO micro-ohmmeters use Kelvin’s 4-point measurement principle which is the most convenient for very small resistance measurements. The measurements are accurate and in accordance with international standards for AC high-voltage circuit breakers testing (IEEE C37.09 and IEC 62271-100).
Starting from 2003, DV Power has been a trend-setter on the market when our first 500 A micro-ohmmeter weighing only 8 kg (RMO500A / CPM500) was released.
Currently, DV Power products portfolio includes 16 models, divided into 3 series:
13 portable models: RMO-A (6) and RMO-G (7) series.
6 handheld models: RMO-H (6) series
The instruments generate a user-selectable and ripple-free test current up to 800 A in an automatically regulated test ramp. Test current ramping significantly decreases the influence of the magnetic transients to measurement.
- Circuit Breaker Test Equipment
- Micro-Ohmmeters
- Circuit Breaker Analyzers & Timers
- Coil Analyzers & Power Supplies
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Micro-Ohmmeters
RMO-A Series
The RMO-A is a portable micro-ohmmeter designed for contact resistance measurements of switchgear during manufacturing, commissioning and maintenance stages. This micro-ohmmeter is widely used by medium and high-voltage circuit breakers manufacturers. Other typical applications are testing of disconnecting switches, high-current bus bar joints, cable splices, and different high-current links. It accurately measures not only in factory environments but also in high-induction fields and substationsThe RMO-A series contains 6 models, rated from 100 A (RMO100A) to 600 A (RMO600A). The RMO500A (formerly CPM500) is our best seller, with 500 A ripple-free current and weighs only 8 kg.Although placed in a very portable and lightweight metal housing, RMO-A micro-ohmmeters have very high output power capabilities. They can generate 600 A test current continuously for up to 20 s. You can test with current up to 100 A without rest time. High output voltage enables a wider measurement range at the highest test currents, as well as the use of thinner/longer test cables. For testing with 100 A, 20 m test leads can be provided with only 16 mm2 cross-section.RMO-A micro-ohmmeter generates a true DC ripple-free (less than 1 %) current with automatically regulated test ramps. During a test, the RMO-A ramps up with increasing current before measuring and decreasing current after the measurement. This significantly decreases magnetic transients and ensures great accuracy.An additional option is a built-in High Precision module suitable for measurement of very low resistances, ranges from 1 to 30 µΩ, with 0,01 µΩ resolution.These instruments can store up to 500 measurements in internal memory. A built-in thermal printer is available as an option.Our free DV Win software communicates with the RMO-A micro-ohmmeters via USB or RS232 interface. It allows you to run the test remotely from PC, as well as to download test results, analyze and generate fully configurable test reports.
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Micro-Ohmmeters
RMO-G Series
The RMO-G is a portable micro-ohmmeter designed for contact resistance measurement of non-inductive test objects and applications with increased safety requirement. It tests medium and high-voltage circuit breakers, disconnecting switches, high-current bus bar joints, cable splices, and different high-current links. Due to its Both Sides Grounded and Remote Control functionalities, the instrument accurately measures even in the most demanding environments, providing additional safety to testing personnel.The RMO800G is the most powerful portable micro-ohmmeter on the market with 800 A output current. RMO200G is our best seller in the USA. A user can choose the appropriate model depending on the output current requirement, from 100 A (RMO100G) to 800 A (RMO800G).We use an unbreakable plastic case with IP67 protective rating (with closed lid) for instruments’ housing. Although very portable and lightweight, RMO-G micro-ohmmeters have very high output power capabilities. High output voltage enables a wider measurement range at higher test currents. Consequently, it enables the usage of thinner/longer test cables. RMO-G generates a true DC ripple-free (less than 1 % ripple) current with automatically regulated test ramps. During the testing, it increases current before measuring and decreases current after the measurement. This significantly decreases magnetic transients and ensures great accuracy.Special current clamps measure a current through groundings when the instrument tests in Both Sides Grounded conditions. The instrument itself powers these clamps. If even higher safety level is required, the Remote Control feature enables the operator to perform measurements from distant locations.RMO-G instruments can store up to 500 measurements in internal memory. Also, they have a built-in thermal printer and USB flash drive available as an option. An additional option is the built-in High Precision module suitable for measurement of very low resistance, in the range from 1 to 30 µΩ, with 0,01 µΩ resolution.Our free DV Win software communicates with the RMO-G micro-ohmmeters via USB or RS232 interface. It allows a user to run the test remotely from a PC. Also, a user can download test results, analyze and generate fully configurable test reports through the software.
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Handheld Micro-Ohmmeters
RMO-H Series
The RMO-H is battery operated and handheld micro-ohmmeter. It is designed for a variety of applications for contact resistance measurement of non-inductive test objects. Typical applications are accurate testing of:medium and high-voltage circuit breakers,disconnecting switches,high-current bus bar joints,cable splices,and different high-current links.Even more, it accurately measures in high-induction filed environments and substations, as well as in factory testing.RMO-H Series contains six models in total, divided in 2 sub-series depending on the test leads length requirement and the battery type:RMO-H1, RMO-H2 and RMO-H3 models are intended for use with short cables (e.g. 1,3 m / 3 m / 5 m). The 1-cell Li-Po battery with 8200 mAh capacity provides output voltage up to 4,1 V DC.RMO-H21, RMO-H22 and RMO-H23 models are ideal for applications where test leads with lengths > 5 m are required. The high output voltage (up to 8,3 V DC) is provided by 2-cells 4100 mAh Li-Po battery.The test current is regulated and can be selected in a range of 1 A to maximum 300 A, depending on the maximum test current rating:RMO-H1, RMO-H21 models – up to 100 A DCRMO-H2, RMO-H22 models – up to 220 A DCRMO-H3, RMO-H23 models – up to 300 A DC.Unlike many other handheld micro-ohmmeters available on the market, our instruments have regulated and user-selectable test currents. Therefore, RMO-H instruments generate an automatically regulated test ramp with stable and ripple-free current during measurement. These revolutionary characteristics in a handheld micro-ohmmeters technology are possible by using sophisticated Li-Po batteries. Consequently, modern battery technology enables you to do multiple measurements, and a full day of testing without recharging the battery.With all RMO-H models, it is possible to make tests on Both Sides Grounded testing objects, in an increased safety environment. Finally, these features in combination with a user-friendly interface (1-click to measure) significantly speed-up testing procedure and make it safer.These instruments store up to 1000 measurements on the internal micro SD card.Our free DV Win software communicates with the RMO-H micro-ohmmeters via a wireless Bluetooth interface. Furthermore, it allows you to download test results, analysis and generate fully configurable test reports.
