In this Nationwide Power™ Case Study, we show the importance of performing preventive maintenance and completing recommendations. This case study is about a Mitsubishi 9900A 150kVA UPS.
After several attempts over the course of many months trying to schedule the first major preventive maintenance inspection (PM), a new customer finally responded by placing an emergency call indicating that there was smoke coming from their uninterruptible power supply (UPS).
| Product | Mitsubishi 9900A 150kVA UPS |
| Application | Communications/Technology |
| Synopsis | The customer was notified by the original equipment manufacturer (OEM) of an AC capacitor recall, which was covered under warranty at no cost. For over a year, the customer did not respond to the OEM to take corrective action, and as a result the AC capacitors failed. This caused smoke, damage, and forced the UPS into bypass, putting their critical load at risk to downtime. |
| Preliminary Actions | A Critical Power Professional™ (CPP™) was dispatched to the site for the first time since this was a new customer. Upon arrival, the CPP found the UPS against a wall with no rear access and was unable to remove the rear panels for proper inspection. The customer was notified that the UPS requires three feet of rear clearance and the CPP returned two days later, after rear access clearance had been provided. |
| Resolution | After the customer cut the wall open behind the UPS for access, the CPP was able to remove the rear panels where a visual inspection presented damage to 3 of the 4 capacitor assemblies. The CPP then shut the UPS down with the load on maintenance bypass. The OEM was onsite two days later and replaced the recalled capacitors, followed by the CPP performing the major PM. |
| Root Cause | Often, businesses choose to defer maintenance for a variety of reasons. In this case study, a deferred recall preceded a PM that may have identified the failing capacitors and avoided an outage. Additionally, the UPS was installed with no rear access, significantly increasing the time to repair. Fortunately, the section of wall that needed to be removed was not a block or exterior wall. In this scenario, it is reasonable to expect that the customer would have avoided all the risk for downtime and costs of having a unit on bypass had the recall been performed. Additionally, the failing capacitors and lack of rear access that hindered the repair would have been identified sooner had Nationwide Power been allowed to perform the major PM. |
| Additional Reading | https://nationwidepower.com/news/case-study-150-the-importance-of-prevention https://nationwidepower.com/news/case-study-145-another-reason-why-preventive-maintenance-is-so-important-liebert-nx-40kva/ |
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