TM495: Thermistor Trip Relay

            Thermistor Trip Relay TM495 This device protects electrical equipment-such as motors and transformers-from damage caused by high temperatures (over-temperature conditions) by operating in conjunction with a PTC thermistor sensor. PTC sensors exhibit low resistance when the temperature is below the nominal operating temperature; however, when the temperature exceeds this threshold, the resistance increases sharply. Since PTC sensors are available in various types based on their nominal operating temperatures, the specific sensor selected determines the temperature at which the relay activates. The TM495 operates as follows:

            When the PTC temperature is below the Nominal Operating Temperature (NOT), Relay K1 turns ON; however, when the temperature exceeds the NOT, the relay turns OFF. When the temperature subsequently drops below the NOT, the relay turns ON if the TM495 is in Auto Reset mode; conversely, if it is in Manual Reset mode, the Reset button must be pressed to turn the relay ON. Additionally, the relay will turn OFF if the PTC sensor experiences a short circuit or an open circuit.