Good afternoon I give an example of a circuit with a thermomagnetic key of 10amp 20 meters of 1.5mm cable and it was short-circuited My question is how long does it take to shoot and if it does it by thermal or magnetic action?

Hello before a short circuit the response is intended to be instantaneous, 0.01 sec. It would be the preset time. However, this will depend on the short circuit intensity and its characteristics. I disagree on some things with the colleague by saying for example that in a short 10A they are reached in a very short time, although that is true, the answer does not depend on the 10A but on the firing curve recognized by a letter before the intensity rated nominal, for example a thermomagnetic C10 is curve C and this establishes that the device can act with intensities between 5 and 10 times the In, that is, the short must reach intensities between 50 and 100A to react magnetically The short-circuit current will depend mainly on the total resistance of the circuit, and this will depend on the distance between the transformer and the short-circuit, passing through all the cables that integrate in its path. the correct operation of the thermal can be affected by the distance between the transformer and the thermal in question (maximum short-circuit current) and the distance between thermal and the short downstream (minimum short-circuit current) in the first case it must be adjusted according to the cutting power of the device, for example 4500A, this means that the device has the ability to clear short circuits up to that intensity, and not only by preventing damage to its coil but by the generation of arcs during takeoff that can prolong the short until the destruction of the facilities and the device itself, for example if we have a short that reaches 5000A before a 3000A device the arc will last even having disconnected and this has the ability to keep the short active for a longer time being able to destroy everything and generate fires, it is not a minor data and you must always know the maximum intensity of presumed short circuit in the second case it is established according to the intensity, the tripping curve and the cutting power, if the distance is very excessive the resistance of the conductors themselves can limit the short-circuit current to below the magnetic actuation parameters of the device, leaving rid of the thermal action that although it will respond, it will not do so in the best time I hope it is understood, any doubt comments The thermal part is for very long duration overloads, there is a non-response intensity that is 1.13 times the In. and a response intensity that is 1.45 times the In for 1 hour, thereafter, depending on the intensity of overload and the duration of the same will be the response or not of the device, the higher the load, the less time reply Regards