| Product | Liebert NPower 130 kVA |
| Application | Hospital Data Operations and Phone Center |
| Synopsis | Load loss prevented during a complete power capacitor and fan replacement. |
| Preliminary Actions | The critical load in this case was transferred to the existing maintenance bypass circuit, allowing full hospital operations to continue while the UPS work was being performed. As part of the UPS isolation, the customer’s UPS feed circuit breaker had to be opened to isolate power to the UPS. Power would continue to flow on the Maintenance Bypass feed circuit breaker. |
| Resolution | The Liebert NPower UPS requires that all input and output power sources be isolated from the UPS during a complete capacitor replacement. This means that either the critical load be shut down or placed on an external maintenance bypass circuit if one is available. The customer was not familiar with the operation of this circuit breaker panel and relied upon the Nationwide Power Field Engineers to operate the circuit breaker. The circuit breaker panel has two circuit breakers. One is the UPS power feed, and the other is the Maintenance Bypass Power feed. Since the Nationwide Power Field Engineers were aware of the damages a critical load loss would incur on the hospital, and having not personally operated the customer’s circuit breakers, they decided to perfom additional precautionary steps. They removed the covers on the feeder circuit breakers, which allowed them to access the cables feeding the UPS and Maintenance Bypass circuit. Using a hand held Amp Meter, they found that even though the critical load had been transferred to the Maintenance Bypass circuit, the UPS circuit breakers were still carrying the load current and the Maintenance Bypass circuit breaker showed no current. Additional investigation was performed, which entailed tracing conduit runs above the drop ceiling. The customer was informed that the circuit breaker panel had been mislabeled. The capacitor and fan replacements were completed without incident, and the UPS was placed back into normal operation to support the hospital equipment. |
| Root Cause | It was verified that the two circuit breakers in the customer’s panel were marked in reverse. Had the Field Engineers simply followed normal procedures and opened the circuit breaker marked UPS Feed, the hospital computer systems and phone system would have lost power creating a situation that could have cost lives. |
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