What might cause an overload relay to trip intermittently?

An overload relay can trip intermittently due to fluctuating loads or incorrect settings. This condition implies that the electrical load on the motor is not stable, which can lead to periods of excessive current draw that may surpass the relay's rated settings, prompting it to trip. In many applications, there are variations in demand that can cause the load to rise and fall unpredictably. If the overload relay is not calibrated correctly to accommodate these changes, it could trip during peaks in load that exceed the established thresholds, even if these peaks are temporary.

In contrast, constant load conditions typically lead to a stable operating scenario; the relay would not trip unless there is a sustained overload, which is not an intermittent issue. A consistent voltage supply would also not contribute to an intermittent trip, as stable voltage ensures that the motor operates within expected parameters. Lastly, while high motor speed may relate to performance issues, it does not inherently cause an overload unless accompanied by increased load factors; therefore, this does not directly lead to intermittent tripping of the overload relay either. Thus, fluctuating loads or incorrect settings are indeed the primary causes of such intermittent trips.