The basics of device circuit breakers | Extended functions
3
Extended functions
The choice of which device circuit breaker is best suited for a given application is based not just on the technology and the associated shutdown behavior . In addition to features such as with or without current-limiting technology or the option to adjust the nominal current , the type of auxiliary contact or signaling and control signals also plays a role .
3.1 Remote control and signaling functions
Reset or control input A reset input can be used to remotely switch a tripped device circuit breaker back on . A control input can be used not just to switch the device circuit breaker back on , but also to switch it on and off during normal operation . This type of operation is similar to that of a relay that is actuated .
Status output A status output is used to output a voltage level at a terminal point that can be sent to a PLC ' s digital input , for example . Normally , a “ HIGH ” signal is output when everything is OK , i . e ., is operational , and a “ LOW ” signal is emitted when the device circuit breaker has been tripped by a fault . The advantage of this signal level definition is that it also covers detection of a wire break in the signaling connection to the PLC .
To use fewer PLC inputs , the signal levels must be exactly the opposite of the ones described above . This can be done by grouping the individual status output signals of multiple single-channel device circuit breakers into one group signal . In that case , you need products with an inverted status output . With these types of products , a “ LOW ” signal is output when everything is OK , i . e ., operational . A “ HIGH ” signal is output when one or more device circuit breakers have tripped due to a fault . However , this means that wire break detection for the signaling connection is no longer an option with these devices .
N / O or N / C signal contact These types of signal contacts involve 2-position potential-free status contacts that can be individually wired and interconnected .
An N / O contact is a normally open contact . This means that the contact is closed when everything is okay . If the device circuit breaker trips due to a fault , the contact opens . Wiring all of the contacts in series makes it easy to construct a simple group signaling arrangement for a group of device circuit breakers . In this case , one end of the series connection must be connected to a + 24 V source , while the other must be connected to a digital PLC input .
An N / C contact is a normally closed contact . This means that the contact is open when everything is okay . If the device circuit breaker trips due to a fault , the contact closes ( Fig . 17 ).
Individual signaling or group signaling Multichannel device circuit breakers are generally equipped with group signaling in the form of a potential-free N / O contact . Single-channel device circuit breakers for the most part are also equipped with one N / O contact for single channel signaling . However , in the case of a group of individual devices , they can also be connected in series and in this way grouped into a group signaling arrangement . This can in some cases save several digital inputs on a PLC as opposed to single-channel signaling .
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