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Microhmmeters

High current micro-ohmmeter

The micro-ohmmeter RMO series instruments are designed for contact resistance measurement of non inductive test objects. RMO micro-ohmmeters are based on state of the art technology, using the most advanced switch mode technique available today. RMO micro-ohmmeters generate true DC current with automatically regulated test ramps. During the test RMO micro-ohmmeters ramp with increasing current before measuring and decreasing current after the measurement. This eliminates magnetic transients.

Typical application areas of RMO micro-ohmmeters are high-voltage substations and industrial environments. An important part of commissioning, maintaining and production is measuring the contact resistance of:

• High, middle and low voltage circuit breakers
• High, middle and low voltage disconnecting switches
• High-current busbar joints
• Cable splices
• Welding joints

Contact resistance is a value that is specified as a reference for all kinds of circuit breakers. According to IEC 56 (now IEC62271-100) this resistance value should be measured using a test current between 50A and the breakers nominal value. According to ANSI C 37.09 the lowest test current is 100A. Other national and international standards specify similar regulations.

	RMO 100	RMO 200	RMO 300	RMO 400	RMO 500	RMO 600
CURRENT RANGE	5A-100A	5A-200A	5A-300A	5A-400A	5A-500A	5A-600A
RESISTANCE RANGE	0,1µΩ-999mΩ	0,1µΩ-999mΩ	0,1µΩ-999mΩ	0,1µΩ-999mΩ	0,1µΩ-999mΩ	0,1µΩ-999mΩ
RESOLUTION	0,1µΩ	0,1µΩ	0,1µΩ	0,1µΩ	0,1µΩ	0,1µΩ
ACCURACY	0,25%	0,25%	0,25%	0,25%	0,25%	0,25%
SINGLE TEST	YES	YES	YES	YES	YES	YES
CONTINUOUS TEST	YES	YES	YES	YES	YES	YES
SOFTWARE	YES	YES	YES	YES	YES	YES
BUILT-IN THERMAL PRINTER	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL

Accessories of the RMO micro-ohmmeters

Cables and clamps

We offer Current Cables with cross sections from 16mm² to 70mm² (16, 25, 35, 50 and 70mm²), with lengths of 3, 5, 10 and 15m. All our Current Cables can be delivered with the following types of clamps: Standard clamps, C clamps, isolated clamps, non-colored clamps and semi-isolated clamps.

Sense Cables are 2,5mm² cross section with lengths of 3, 5, 10 and 15m. Extension Cables are with cross sections from 16mm² to 70mm² and with lengths of 5m and 10m.

[Standard clamps]
[C Clamps]	[Isolated clamps]
[Non-colored clamps]	[Semi-isolated clamps]

Remote Control Unit

The RMO Remote Control Unit is an optional control unit that is used to start and stop the tests from a remote location, away from the actual RMO micro-ohmmeter. Very often the same test current is fed through the test object for a series of tests. To simplify this and speed up the process, multiple measurements can be carried out with the RMO Remote Control Unit.

Transport Bags, Transport Case

We offer transport bags (device bag and cable bag) as a standard accessories.
Also, we offer hard transport case as an optional accessory which improves mechanical protection of devices in transport.

Current Clamp meter

Using micro-ohmmeters with current clamp meter it is possible to make safer measurement of breakers with both sides of the breaker grounded. It is performed by measuring the current through the ground connection and reducing this value from the total current. This is an optional accessory.

Test shunt

We offer test shunt 600A/60mV. It could be used for accuracy checking of our Micro-ohmmeters.

Built-in thermal printer

We deliver devices with 80mm paper wide built-in thermal printer, as an optional accessory.