The basics of device circuit breakers | Glossary
Power dissipation in nominal operation No-load power dissipation describes the closed-circuit current of the circuit breaker that is needed for auxiliary power consumption . Maximum power dissipation in nominal operation refers to the power output that occurs in all circuits ( main circuit , control circuit , signaling circuit ) while operating under the highest rated current and highest rated voltage , plus the power dissipation for auxiliary power consumption .
Rated current Rated current I N in the context of circuit breakers is understood as the current that may flow continuously under the conditions established by the manufacturer and at which the circuit breaker must not trip . The conditions include the nominal voltage , the ambient temperature , and the installation position , for example .
Rated short-circuit switching capacity The rated short-circuit switching capacity I cn is the maximum current that a circuit breaker should switch on , conduct while open , and shut down under specified conditions . In this case , the rule applies that the twice repeated switching on to a short circuit must be also successfully managed by the circuit breaker .
Rated values Values for which a piece of equipment is rated , e . g ., rated current , voltage , frequency .
Rated voltage Rated voltage U N in the context of circuit breakers is understood as the voltage value to which the operating and performance characteristics refer .
SFB characteristic curve in thermomagnetic circuit breakers ( SFB , Selective Fuse Breaking ) Device circuit breakers that work on the basis of this characteristic curve trip more easily in the event of a short circuit . The SFB tripping characteristic falls between the M1 and F1 characteristic curve .
SFB technology in power supplies ( Selective Fuse Breaking ) Power supplies that operate based on this technology provide a high current reserve in the event of a short circuit . Even for long cable paths , the safety equipment is supplied with the required breaking current . Any unaffected system parts also connected to this power supply continue to be supplied with power .
Short-circuit current This current arises between an incorrect low-resistance connection between two points , which usually have different potentials .
Short-circuit detection Phoenix Contact electronic circuit breakers are equipped with intelligent short-circuit detection . This enables them to start loads with high starting currents even in the short-circuit tripping range while also detecting even small short-circuit currents as such and shutting them off within a few milliseconds .
Short-circuit tripping range Thermomagnetic and electronic circuit breakers have a short-circuit tripping range that , depending on the type , corresponds to 1.5 to 15 times the nominal current value . Shutdown in this case takes place within a few milliseconds .
Switching cycles Sequence of actuations from one position to another and back .
Temporary dielectric strength Maximum temporary voltage value that can be tolerated without causing any insulation damage under specified conditions .
Trip-free mechanism Tripping of a device circuit breaker that does not involve any change in the switch position of the operating lever .
Tripping characteristics Tripping characteristics indicate the tripping behavior of a device circuit breaker . The switching time and amperage at which a circuit breaker trips are shown in a diagram .
Tripping range The tripping behavior cannot be defined using a single precise characteristic curve . The internal components are subject to certain tolerances . For that reason , a tripping range within which the device circuit breaker operates is specified . Electronic circuit breakers also have tolerances , but they fail at significantly lower rates and therefore provide more accurate protection .
Type of actuation Describes how a device circuit breaker is operated or reset . Versions are available with automatic reset or versions with manual actuation . These are equipped with an operating lever for regular or irregular switching operations .
80 % early warning The early warning signals that 80 % of the preset nominal current has been reached for each channel .
PhoENix CoNtACt 31