Often during the rebuild and overhaul of a piece of electrical apparatus, we are faced with the challenge to identify the type of temperature detection devices that need to be replaced.Types of temperature detectors discussed include: Resistance Temperature Detectors (RTDs) Thermocouples Thermistors Thermostats

When we mention temperature detectors for motors we usually think of winding temperature detectors. However, temperature detectors can also be used to monitor bearings and airflow. In this article we will describe the more common types of temperature detectors and how they can be applied to windings, bearings and to check ventilation (airflow). 

There are a number of different types of winding protection devices used with motors. However, they all basically do the same thing; they sense a change from the normal operating temperature and either sound an alarm or take the motor off line when the specified temperature limit has been met or exceeded. Temperature protection is not limited to just large motors. A smaller motor that is critical to operation would be a good candidate for winding temperature protection if a failure would cause significant costs due to downtime.