Curva Disjuntor
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The disjuntor curve calculator is a practical tool to determine the short-circuit current in an electrical system. It uses the formula I = Ø × I_m to calculate the short-circuit current, where I is the short-circuit current, Ø is the curve constant of the disjuntor and I_m is the nominal current of the disjuntor.
This calculator is especially useful for electrical system designers and installers, who need to determine the short-circuit capacity of a disjuntor according to the protection class (B or C) and the nominal current (I_m).
Correctly choosing the disjuntor according to the protection curve is crucial to ensure the safety of electrical systems and prevent damage to equipment and people.
Additionally, it is essential to consider common precautions when using this calculator, such as the accuracy of the input data and the verification of compatibility between the disjuntor and the electrical system.
Frequently asked questions
What is the protection class of the disjuntor?
The protection class of the disjuntor is determined by the curve constant (Ø) and the nominal current (I_m). Class B is characterized by a curve constant of 0.02 to 0.4 and a nominal current of 3 to 5 times the nominal current. Class C is characterized by a curve constant of 0.02 to 0.4 and a nominal current of 5 to 10 times the nominal current.
How do I choose the correct disjuntor?
To choose the correct disjuntor, you need to determine the short-circuit current of the electrical system and choose a disjuntor with a curve constant and nominal current compatible with the desired protection class.
What happens if I choose an inadequate disjuntor?
If you choose an inadequate disjuntor, it may cause damage to equipment and people, as well as compromise the safety of the electrical system.
How can I ensure the accuracy of the calculator?
To ensure the accuracy of the calculator, it is essential to verify the accuracy of the input data and ensure the compatibility between the disjuntor and the electrical system.