Six months ago, a new production line was installed. Under the company's new cost-cutting program, a three-bid system awarded the electrical work to a firm whose bid was far lower than that of the firm the plant had been using for years. The system has been buggy ever since.
The plant manager wants you to figure out what’s wrong. To help you get started, he gave you a report generated by the computerized maintenance management system (CMMS). This report is based on the reason code entered for each maintenance call. These failures have the highest incident rate:
- Dead circuit board.
- Malfunctioning controller.
- Operator screen failure.
- Electric shock to personnel.
- Random shutdown, no cause identified.
- Gearbox bearings failed.
- Motor bearings failed.
How might you get to the bottom of this?
It is rare that a company ever saves money by going with a lowball bidder. In this case, the company has paid dearly for that. Clearly, many shortcuts were taken to come in at that lowball price.
The failures with the highest incidence rate point toward bonding deficiencies. Your equipment grounding conductor (EGC) and the bonding jumpers that connect to it provide a ground-fault current path and connect normally non-current carrying metal parts of equipment. A methodical inspection will reveal many deficiencies; fix those, and your failure rate will drop dramatically.
Then turn your attention to workmanship issues. Start with thermographic scans of connections. Conduct Ohmic measurements across suspect connections; repair bad ones.
