In this EC&M Tech Talk Randy Barnett, Master Electrician, discusses the fundamental electrical testing requirements found in the NFPA 70B Standard for Electrical Equipment Maintenance. An introduction points out how to use the 70B to determine what equipment to select for maintenance, how often to perform these tests and exactly which tests to perform. Next, the testing is gone into in more detail.
Bolted connections and terminations must be tested to prevent overheating. Different options are available including applying a “maintenance level” torque, using a micro-ohmmeter or observing temperature.
Insulation breaks down over time and its quality must be measured. Two important factors are temperature and the length of time the test voltage is applied. These factors are explained to help achieve more accurate and consistent readings. Infrared thermography (IR) testing is a great predictive maintenance tool as troubles can often be spotted before they escalate into catastrophic overheating issues. However, it is not the actual temperature of the equipment that is so important. Comparing and analyzing results is key.
By incorporating the fundamental electrical tests into an electrical preventive maintenance program, downtime can be reduced, unplanned outages can be minimized, the time spent on maintenance can be reduced and most importantly, safety is improved!
