The basics of device circuit breakers | Extended functions
Marking the connections :
Main contacts |
Individual : |
1 - 2 |
In groups : |
1 - 2 / 3 - 4 / 5 - 6 / … |
Auxiliary contacts – Individual N / O contact : 13 - 14 – N / O contacts in groups : 1.13 - 1.14 / 2.13 - 2.14 /
3.13 - 3.14 / … – Individual N / C contact : 11 - 12 – N / C contacts in groups : 1.11 - 1.12 / 2.11 - 2.12 /
3.11 - 3.12 / …
Fig . 17 : Setting for auxiliary contacts based on switching state of the main contact Power main contact Signal auxiliary contacts NO normally open ( N / O ) contact NC normally closed ( N / C ) contact C common changeover foot contact ( common )
3.2 Nominal currents – Fixed or adjustable
The correct nominal current for a device circuit breaker can be determined either at time of purchase or left open up until the time it is installed in the application . This means that the decision involves choosing either a product with a fixed nominal current or one with an adjustable nominal current range . The latter option allows you to separately adjust to the nominal current that is right for the application , e . g ., using a potentiometer , step switch , or onebutton operation . One major advantage of this adjustability is that you still have the freedom to respond to adjustments and revisions in the system up until the devices are installed . This option is available with fixed-value devices only in cases where the decision is made to use pluggable versions . In that case , the nominal current remains unspecified until the choice of which device circuit breaker connector to use is made .
3.3 Adapted backup fuses
In electronic circuit breakers , a backup fuse is built in to serve as a fail-safe element . This is done to cover the rare instance of a technical failure in the main switching element ( MOSFET ) to protect it from thermal destruction . A fail-safe element is required under the American UL standards . An electronic fuse is considered to be an electrical device . That means it must also be protected . This can be done via an external fuse , but is not necessary thanks to the fuse already incorporated in the electronic circuit breaker .
The size of the backup fuse should match the application , for which reason devices with a low maximum nominal current are also available , so as to better protect sensors or other sensitive loads .
PhoENix CoNtACt 17