What happens if the heater size in a thermal overload unit is not changed?

If the heater size in a thermal overload unit is not changed to match the specific requirements of the motor it protects, the unit may not function properly. The thermal overload relay is designed to monitor the amount of current flowing through the motor. If the heater size is incorrectly set, it can lead to inaccurate sensing of the motor's temperature and current load.

For example, if the heater is too small for the motor's operational range, it may trip too frequently, leading to unnecessary downtime. Conversely, if the heater is too large, it may not trip at all under operating conditions that could potentially overheat the motor. This miscalibration can cause ineffective protection, resulting in damage to the motor or eventual failure due to overheating or excessive current draw. Proper sizing ensures that the thermal overload unit can accurately protect the motor from overcurrent conditions, thus maintaining effective operation and longevity of the equipment.