Application:
Motor protection based on PTC sensors is one of the most effective and reliable protective measures against thermal overload in electrical machines. The protection unit is composed of the INT69 motor protector and the PTC sensors. Due to its compact construction, the INT69 is suitable for installation in electrical devices or in the terminal boxes of electrical machines.

Functional description
At the measuring circuit input of the INT69, it is possible to connect up to nine DIN 44081, DIN 44082 conform PTC sensors. Sensors with different nominal response temperatures may be used. Thus it is possible to monitor several measuring points with only one INT69 motor protector. If the temperature in one of the monitored parts or sections reaches the nominal response temperature of the respective PTC sensor, the sensor becomes highly resistive and the motor protector switches off. The device switches itself on again after cooling back down.

The relay's switching output is a potential-free changeover contact. This circuit works in accordance with the closed-circuit principle, i.e. even in the event of a sensor or cable break, the relay returns to its rest position and switches off.

Only the output relay is galvanically isolated.

 

....The mounting, maintenance and operation are to be carried out by an electrician. The valid European and national standards for connecting electrical equipment and cooling installations have to be observed. Connected sensors and connection lines that extend from the terminal box have to feature at least a basic.