Application
The motor protector based on PTC sensors provides one of the most effective and reliable protective measures against thermal overload of electrical machines. The protection device is composed of the INT69 G motor protector and the PTC sensors. Due to its compact construction, the INT69 G is suitable for installation in electrical equipment or in the terminal boxes of electrical machines.
Functional description
At the measuring circuit input of the INT69 G, 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 G 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. After cooldown, restarting is only possible if the electronic lock of the output relay is released by interrupting the voltage supply. Ex works the lock-out bridge is installed at terminals B1-B2. Alternatively the locked version can be changed to an unlocked version by removing bridge B1-B2. In that case the device switches itself on again after the cooldown. The relay switch output is designed as a potential free change-over contact. This switching circuit function according to the closedcircuit principle, i.e. the relay drops back to the reset position also in case of sensor or cable failure and shuts off. The sensor, relay and supply circuits are galvanically isolated from each other