What does it indicate if a contactor coil shows erratic resistance readings?

If a contactor coil shows erratic resistance readings, it indicates that there may be a failure in the coil. A contactor coil is designed to have a specific resistance value, reflecting its operational integrity. When resistance readings fluctuate or do not remain stable, it suggests that there might be internal damage or degradation within the coil. This could be due to factors such as overheating, insulation breakdown, or age-related wear, which can compromise the coil's performance.

In contrast, if the contactor were functioning normally, the resistance readings would be consistent and within the expected range. An overloaded circuit typically wouldn’t necessarily manifest as erratic resistance in the coil; instead, it may lead to tripping breakers or reduced functionality. Power supply issues might affect the operational status of the contactor, but they wouldn't directly cause erratic resistance readings. Therefore, erratic readings are a strong indicator of an internal coil failure that requires attention.