LAS CRUCES, NM – On Monday, January 16 and Tuesday, January 17, 2017, El Paso Electric (EPE) experienced power outages that affected approximately 27,000 customers each day. El Paso Electric was performing maintenance on a transformer in the Las Cruces Substation as part of our regular maintenance plan before the summer.
The outage on January 16 was reported at approximately 4:29 p.m. and power was restored at approximately 5:35 p.m. The outage on January 17 was reported at approximately at 8:34 p.m. Power was restored to most customers at approximately 8:57 p.m. and all remaining customers at approximately 10:13 p.m.
EPE’s investigation reveals that the outages can be attributed to problems with the protective devices of the system, which occurred under a unique situation. The protective devices which are a part of the electrical grid are intended to stop major damage to equipment that could result in the longer duration of outages or unsafe condition. These levels of protection are coordinated so as to minimize the number of customers affected due to a short circuit, or a fault, on any distribution circuit.
Both events were initiated as a result of a fault on a distribution circuit. In both cases, the secondary level of protection went off prior to the primary level of protection. As a result, all of the distribution circuits in this substation were interrupted rather than just the one distribution circuit that had the fault.
EPE engineers identified the problem and are developing new settings that will minimize the risk of a similar future event.