Recommended Circuit Breaker Stress Factor
Contact Application | .. | Contact Derating Factor |
Resistive | 0.75 percent | |
Capacitive | 0.75 | |
Inductive | 0.40 | |
Motor | 0.20 | |
Filament | 0.10 |
Circuit Breakers should be operated at 20C below the maximum temperature specified.
Derating Factors [the numbers shown above] are used for many components and just mean that for a given application, the component should be derated by some percentage from its maximum operating limits. A dearting factor is always given in a percentage.
In this particular case the maximum limit to be controlled is current. So the recommendation in this case, for this component, is to never operate the device in a system that would require 100 percent of the current handling ability of the device. In other words, using the example above, if a circuit breaker is being used in a system with a resistive load, the load should be no greater than 75 percent of the maximum current the circuit breaker is designed to handle. So, for proper design never use a circuit breaker that indicates a 100 amp current rating in its data sheet for a circuit that requires 100 amps.
Unless indicated, contact current is assumed to be resistive.