DV Power’s micro-ohmmeter lineup is built around the RMO name. In general, RMO refers to a low-resistance or micro-ohm measurement instrument that uses high DC test current for applications such as contact resistance testing, bonding checks, ground path verification, and winding-related resistance measurements.
The number in the model name usually indicates the maximum test-current class. For example, RMO100A, RMO300A, and RMO600A belong to the RMO-A family, with the number pointing to the 100 A, 300 A, or 600 A current class.
However, the suffix letter is the most important part of the name when selecting the right instrument. The letter tells you the product family and the main application focus.
Main Naming Pattern
RMO-A is the standard portable micro-ohmmeter family.
These instruments are commonly used for general contact resistance measurement on switchgear, circuit breakers, busbars, joints, and other non-inductive test objects. Models such as RMO100A through RMO600A mainly differ by maximum output current.
Choose RMO-A when you need a straightforward, high-current portable micro-ohmmeter for general field or maintenance testing.
RMO-G is the safety-focused portable family.
The G family is designed for applications where Both Sides Grounded testing is important. This is especially useful in high-voltage environments where grounded circuit breakers and switchyard equipment must be tested with additional safety considerations.
Models in this family run up to the RMO800G class.
Choose RMO-G when the test procedure requires both sides of the equipment to remain grounded during testing.
RMO-C is the continuous-current family.
The C series is built for users who need sustained current output rather than short high-current bursts. This makes it a strong fit for demanding contact resistance work where continuous current stability matters.
Models include RMO200C, RMO300C, and RMO500C.
Choose RMO-C when the application requires longer current injection or stronger output stability during testing.
RMO-H is the handheld family.
These models are battery-operated, compact, and designed for field use. They are best suited for technicians who need maximum portability and fast on-site testing. DV Power lists the RMO-H family as handheld, lightweight, and capable of regulated current up to 300 A DC.
Choose RMO-H when portability and battery operation are more important than the highest available current class.
RMO10H and RMO-EH are 10 A handheld low-resistance testers.
These instruments are not direct replacements for high-current breaker micro-ohmmeters. Instead, they are better suited for protective bonding, long test leads, wind turbine lightning protection systems, and general low-resistance checks where 10 A is enough.
Choose RMO-EH or RMO10H when the application is focused on continuity, bonding, or safety verification rather than high-current breaker contact testing.
How to Select the Right DV Power RMO Model
For general breaker contact resistance, choose RMO-A.
This is the clean default when you need a portable, high-current micro-ohmmeter and do not have a special safety or continuous-current requirement.
For high-voltage yards or grounded breaker testing, choose RMO-G.
The G family is the better fit when Both Sides Grounded testing is part of the job procedure.
For continuous high-current testing, choose RMO-C.
Pick this family when the test requires longer current injection or stronger output stability.
For maximum portability, choose RMO-H.
Use it when technicians need a handheld unit for fast field checks and battery-powered operation.
For wind turbines, bonding, or long-cable low-resistance checks, choose RMO-EH or RMO10H.
These are practical when the required current is around 10 A and the job is more about continuity, bonding, or safety verification than high-current breaker contact testing.
Practical Rule of Thumb
If you only remember one thing, remember this:
The number tells you the current class, but the letter tells you the job.
A = standard portable micro-ohmmeter
G = grounded and safety-oriented testing
C = continuous-current testing
H = handheld portability
EH / 10H = 10 A handheld low-resistance and safety applications
For sales or technical selection, start with the application first, then choose the current level.
A customer asking for contact resistance testing on circuit breakers may need an RMO-A. A customer asking for testing while both sides are grounded likely needs an RMO-G. A customer working on wind turbine lightning protection or protective bonding may be better served by RMO-EH or RMO10H, even though the current is much lower.
Choosing the right DV Power micro-ohmmeter is not only about selecting the highest current rating. It is about matching the instrument family to the actual field requirement.
The table below provides a quick comparison of DV Power’s main RMO micro-ohmmeter families, including model range, current capacity, resistance range, and key application features. It can help users narrow down the right series before selecting a specific current class.
| Feature |
RMO-C |
RMO-G Series |
RMO-A Series |
RMO-H Series |
| Models |
RMO200C, RMO300C, RMO500C |
RMO100G, RMO200G, RMO300G, RMO400G, RMO500G, RMO600G, RMO800G |
RMO100A, RMO200A, RMO300A, RMO400A, RMO500A, RMO600A |
RMO-H1, RMO-H21, RMO-H2, RMO-H22, RMO-H3, RMO-H32 |
| Current Range |
Up to 500 A DC |
Up to 800 A DC |
Up to 600 A DC |
Up to 300 A DC |
| Resistance Range |
0.1 µΩ – 999.9 mΩ, expandable to 6000 mΩ |
0.1 µΩ – 999.9 mΩ |
0.1 µΩ – 999.9 mΩ |
0.1 µΩ – 3000 mΩ |
| Both Sides Grounded Testing |
Yes |
Yes |
No |
Yes |
| Dead-Tank Circuit Breaker Testing |
Yes |
Yes |
Yes |
No |
| High-Precision Module |
Yes |
Yes |
Yes |
No |
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