Testing electrical insulation can be quick and easy when using test equipment specifically designed to perform insulation resistance measurements. A good insulator should have a very high resistance to current flow. Factors such as temperature, electrical and mechanical stresses, weather and moisture ingress are all capable of adversely impacting the characteristic qualities of materials that make them such good insulators. The degradation of these materials over time can result in unplanned outages, safety concerns for personnel and an overall degradation of power system reliability.
An insulation resistance test is conducted to examine the effectiveness of insulation in a variety of electrical power system apparatus. Faulty electrical insulation is the source of dangerous shock hazards and can often cause ancillary damage to adjacent equipment as well. Routine electrical testing and maintenance can help to identify when insulation has deteriated before it reaches the point of failure, saving the expense of repairs and unplanned outages.
Protective Relays could be characterized as circuit managers with varying degrees of supervisory and control capabilities depending on the complexity and criticality of the circuit. They are designed to recognize abnormal or fault conditions, and to isolate the affected portion or the electrical system. Not only does this allow the unfaulted portion of the electrical system to continue to function normally, but it diminishes the impact of the faulted portion of the system. Changes to power system circuits and the coordination of protective devices can change due to age, loading, environmental impacts, new construction, etc. It is therefore critical that these devices function properly and are appropriately coordinated when they are called into action.
Sweep Frequency Response Analysis (SFRA) is an electrical testing method which identifies changes to the internal workings of a transformer. The transformer is an electrical filter that has a specific response to each independent input frequency. The test equipment is used to apply a test voltage to a transformer over a range of frequencies.
The output of the transformer is then monitored in relation to its corresponding input frequency. The results, when graphed, make up a signature response, much like a unique fingerprint. The initial SFRA test will then become a baseline for comparison when future tests are performed. When these signatures do not match the baseline signature, something has changed internal to the transformer and merits further investigation.
Relays are often utilized in electrical facilities as isolated switches or protective devices for various electrical equipment. Due to the mechanical operation of relays, the contacts are prone to contact degradation, so it is important to regularly test for the electromechanical, electronic and protection schemes to ensure safe and reliable operation, and to avoid a faulty relay system acting up during critical operations. To assess relays and protections schemes, consider investing in a relay test set or a power system simulator.
Can't find what you are looking for here? Be sure to checkout the entire Protec Resource Blog Archive.