Several motors supplied by the same MCC blow their overloads at about the same time, but the occurrence seems random. Everything will be normal for weeks, then suddenly, all of the motors have open overloads.
Over the past year, each of the motors has passed a battery of tests performed by the motor repair shop your plant has been using for many years. Voltage checks show normal supply voltage. Alignment checks have all come up “within spec” and there’s no excess vib