currents that run through the supply conductors and entering and leaving the difference are identical, whether for lack of insulation, such as an appliance, there is a dispersion of current a conductor carrying a current supply is less than the other if the difference between the currents is likely to pass at least half of the rated current of the differential action, which operates the circuit breaker opens the circuit stopping the power supply.
breaker
On external
Under Internal
The differential shall cease to operate the power supply when the fault current is dispersed in time and with an intensity lower than preset , beyond which, if the current were to take the human body, lacking the plant ground, there would be reversible physiological effects (cardiac arrest, respiratory arrest, muscle cramp) and irreversible (cardiac fibrillation, respiratory arrest). To test the differential
presses the test button, but it is a rough test to see if the release mechanism is working.
A study conducted by the Polytechnic of Turin on the efficiency of 21,147 circuit breakers installed in various places has shown that by pushing the test button, it was found that 24% of circuit breakers are defective.
The test button is used to maintain the circuit breaker in operation, otherwise the effect can glue undermining the proper functioning of the Left for a long time.
Indeed, the differentials which are closed once a month, have a failure rate equal to half that of the other switches.
If the circuit breaker works with the test button to say that he is alive, but not necessarily be in good health.
impossible to estimate the field, the actual state of health of the differential if they can evaluate its effectiveness only for protection against indirect contact with the grounding system.
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