Low resistance measurements

Micro-ohmmeters are essential instruments for measuring very low resistances in electrical power systems. They enable the early detection of loose connections, overheated contacts and hidden defects before these issues result in failures or fire hazards. This article explains how the four-wire Kelvin measurement method works, why a high test current is essential, and how Sonel MMR-6500 and MMR-6700 micro-ohmmeters support diagnostics of circuit breakers, busbars, cables, earthing systems, transf

Measure the HV circuit breaker and transformer with one device SONEL S.A. introduced microohmmeters with a measuring current up to 200 A, dedicated to testing resistance of high voltage circuit breakers, resistive objects as well as transformers and motors. As a result of burning an electric arc, carbon deposits accumulate on the HV circuit breaker contacts. As a consequence, the actual conduction surface decreases, and the resistance and heating rise, which leads to a fall in the effi