A Microohmmeter is a handheld device that is designed for the precise measurement of extremely low resistance values. These instruments are useful in a wide range of industries. Among the most important uses of a micro-ohmmeter are to check circuit breakers for carbonised layers at their contact points and other connections in power transmission and distribution systems, new energy vehicles etc.

Accuracy

A Microohmmeter is a dedicated low resistance ohmmeter that measures incredibly small values of resistance. It is far more accurate than general purpose multimeters with four terminal connections when measuring very low levels of resistance. This makes them essential tools for technicians who are testing connections or bonding joints.

We carry a large selection of professional micro-ohmmeters from industry leaders like Extech and AEMC. Many of these models include features to compensate for the effects of temperature on resistance. This is especially useful when measuring the resistance of components whose properties change with temperature.

This hand-held 200A digital micro ohmmeter is ideal for measuring very low resistance in substation applications such as circuit breakers, switches, busbars and cable joints. Its programmable test current and high resolution allow you to select the exact measurement range needed for your application. It also features double test probes and Kelvin clamps for very low contact resistance measurements on equipment, transformers and cables.

Ranges

OM 21 benchtop micro-ohmmeter is ideal for low resistance measurement in a range of applications: cable resistance and resistivity measurement, inductive resistance (coils, transformers winding resistance) test, contact resistance measurement of connectors, switches and relays, metallisation / earth bonding and ground continuity test. Fully programmable by the user through the instrument interface or directly through LOG OM software delivered in option, you can choose among six set configurations inside the meter and configure the measuring current, measuring unit, metal under test and triggering conditions.

Transcat offers a wide selection of professional DLROs and micro-ohmmeters from leading manufacturers like Megger, Extech, AEMC and Reed instruments. Whether you’re testing high-voltage circuit breakers or disconnecting switch contacts, knife-contact fuses or bus bar joints, these micro-ohmmeters will provide you with the performance and accuracy you need in confined spaces and challenging environments. They come with four-wire Kelvin probe systems to eliminate contact resistance errors and a portable, rugged case.

Power

Until recently, most high-current micro ohmmeters were mains-powered 100A or 200A instruments that needed an associated power supply and generator to provide the current for test operation. This limited their adoption and required time-consuming set up. Megger now offers a battery-powered handheld 200A micro ohmmeter that eliminates this limitation, making these powerful tools more portable and convenient for use in substations.

The OM 10 portable micro-ohmmeter is a 4-wire instrument that measures both inductive and non-inductive resistances to 50 k with continuous or pulsed measuring current up to 100 mA. It features a high basic accuracy, selectable component drive modes to avoid thermal EMF effects and polarity reversal for easy zeroing. This unit is ideal for inspecting switch and fuse contacts, electrical substation wiring, welding points, and leads. It can also perform dry circuit tests based on several MIL specifications. This meter is powered by four 3400mAh, 3.7Vdc Li-Ion rechargeable batteries that can perform up to 2,900 tests per charge (10A/2 second). It has an alphanumeric display with up to 4 1/2-digit resolution.

Display

The Micro Ohmmeter has a bright and clear display that is easy to read in any light condition. It simultaneously displays current, sense voltage, and resistance to provide comprehensive insights into the measurement results. Additionally, the instrument supports a USB keyboard that allows users to input comments that are stored with the measurement results. This feature streamlines the analysis and record-keeping process.

This digital high-current micro-ohmmeter is a portable, microprocessor-controlled instrument for accurate measurements of very low contact resistances in circuit breakers and switches, transformer and motor windings, wire and cable samples, as well as busbar joints. It uses the four terminals measurement method to eliminate errors due to test leads and their contact resistances.

Measurement operation is simple: just connect the leads, switch on the equipment, select the test current and press the start button. After a few seconds (depending on inductance of the element), direct reading appears on the alphanumeric display with the measure unit indication (O, mO or uO) and messages to help the operator (Low battery, Over range etc). The equipment is housed in a sturdy plastic case, with hinged lid and carrying handle, suitable for use outdoors and under severe weather conditions.

More Words

A microohmmeter is a device designed to measure low resistance values. These devices typically use a four wire Kelvin probe system to eliminate the effects of test leads and contact points on measurement accuracy. Arcing at circuit breaker contacts causes carbonised layers that increase the live contact resistance and over time can lead to failure of the breaker or other substation equipment. This problem can only be prevented by checking the resistance of each breaker at very low currents.