The resistance of an electrical connection increases over time due to temperature, cycling, and other environmental stresses. The degradation of these connections can result in excessive losses due to heating and operability issues . Periodic testing of contact resistance and/or other electrical bonds can help to identify changes in the condition of contacts and other electrical connections.
Air, moisture, mechanical and electrical stress can all impact electrical pathways through power system apparatus. These stresses have the ability to degrade connections and points of contact throughout the electrical system. The increased resistance between contacts or bonding points can cause thermal damage to power system apparatus and the conductors that connect them. Power losses due to high resistance connections are also a significant consideration as they impact the overall operating costs for power generation and delivery. All of these factors can potentially lead to the failure of power systems and the ability to provide electrical service.
A digital low resistance ohmmeter or DLRO can measure the resistance associated with bonds and electrical connections within the electrical power system. The resistance of these connections should be within a tolerance corresponding to the manufacturer's recommendations or industry standards for the materials and/or devices being tested. Higher than expected values of resistance are an indication of future challenges to power system reliability and can be utilized as a tool for the mitigation of these potentially costly issues.
Protec offers a full line of digital low resistance ohmmeters from AEMC, Megger, Raytech, Vanguard and other leading manufacturers:
Editor’s Note: This post was originally published on December, 2010 and has been updated freshness, accuracy and comprehensiveness.